Showing papers in "Journal of Environmental Sciences-china in 2022"
TL;DR: Under the optimized reaction condition, CCCN/PS is able to give 99% degradation extent and 74% chemical oxygen demand removal in assistance of simulated solar light, both of which are apparently greater than that of either CuO/CuFe2O4 and pristine g-C3N4.
Abstract: In this study, a graphitic carbon nitride (g-C3N4) based ternary catalyst CuO/CuFe2O4/g-C3N4 (CCCN) is successfully prepared thorough calcination method. After confirming the structure and composition of CCCN, the as-synthesized composites are utilized to activate persulfate (PS) for the degradation of organic contaminant. While using tetracycline hydrochloride (TC) as pollutant surrogate, the effects of initial pH, PS and catalyst concentration on the degradation rate are systematically studied. Under the optimized reaction condition, CCCN/PS is able to give 99% degradation extent and 74% chemical oxygen demand removal in assistance of simulated solar light, both of which are apparently greater than that of either CuO/CuFe2O4 and pristine g-C3N4. The great improvement in degradation can be assignable to the effective separation of photoinduced carriers thanks to the integration between CuO/CuFe2O4 and g-C3N4, as well as the increased reaction sites given by the g-C3N4 substrate. Moreover, the scavenging trials imply that the major oxidative matters involved in the decomposition are hydroxyl radicals (•OH), superoxide radicals (•O2−) and photo-induced holes (h+).
74 citations
TL;DR: The core theme of this paper is to seek to treat CO2 as a commodity instead of a liability.
Abstract: CO2 utilizations are essential to curbing the greenhouse gas effect and managing the environmental pollutant in an energy-efficient and economically-sound manner. This paper seeks to critically analyze these technologies in the context of each other and highlight the most important utilization avenues available thus far. This review will introduce and analyze each major pathway, and discuss the overall applicability, potential extent, and major limitations of each of these pathways to utilizing CO2. This will include the analysis of some previously underreported utilization avenues, including CO2 utilization in industrial filtration and the processing of raw industrial materials such as iron and alumina. The core theme of this paper is to seek to treat CO2 as a commodity instead of a liability.
68 citations
TL;DR: A promising approach based on singlet oxygen-dominated nonradical reaction for eliminating TC in water treatment is provided and the toxicity of treated TC was greatly reduced by using microalgae Coelastrella sp.
Abstract: Nonradical reaction driven by peroxymonosulfate (PMS) based advanced oxidation processes has drawn widespread attention in water treatment due to their inherent advantages, but the degradation behavior and mechanism of organic pollutants are still unclear. In this study, the performance, intermediates, mechanism and toxicity of tetracycline (TC) degradation were thoroughly examined in the constructed magnetic nitrogen-doped porous carbon/peroxymonosulfate (Co-N/C-PMS) system. The results showed that 85.4% of TC could be removed within 15 min when Co-N/C and PMS was simultaneously added and the degradation rate was enhanced by 3.4 and 14.7 folds compared with Co-N/C or PMS alone, respectively. Moreover, the performance of Co-N/C was superior to that of most previously reported catalysts. Many lines of evidence indicated that Co-N/C-PMS system was a singlet oxygen-dominated nonradical reaction, which was less interfered by pH and water components, and displayed high adaptability to actual water bodies. Subsequently, the degradation process was elaborated on the basis of three-dimensional excitation-emission matrix spectra and liquid chromatography-mass spectrometry. At last, the toxicity of treated TC was greatly reduced by using microalgae Coelastrella sp. as ecological indicator. This study provides a promising approach based on singlet oxygen-dominated nonradical reaction for eliminating TC in water treatment.
63 citations
TL;DR: This review summaries the recent works on ACM-based composites in photocatalysis, focusing on the properties of surface and layered structure, and overview the modifications onACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process.
Abstract: Aluminosilicate clay mineral (ACM) is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring. In past two decades, in-depth understanding on unique layered structure and abundant surface properties endows ACM in the emerging research and application fields. In field of solar-chemical energy conversion, ACM has been widely used to support various semiconductor photocatalysts, forming the composites and achieving efficient conversion of reactants under sunlight irradiation. To date, classic ACM such as kaolinite and montmorillonite, loaded with semiconductor photocatalysts has been widely applied in photocatalysis. This review summaries the recent works on ACM-based composites in photocatalysis. Focusing on the properties of surface and layered structure, we elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM, i.e., type 1:1 and type 2:1. Not only large surface area and active surface hydroxyl group assist the substrate adsorption, but also the layered structure provides more space to enlarge the application of ACM-based photocatalysts. Besides, we overview the modifications on ACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process. This review could inspire more upcoming design and synthesis for ACM-based photocatalysts, leading this kind of economic and eco-friendly materials for more practical application in the future.
63 citations
TL;DR: In this paper , nitrogen-doped porous carbons were synthesized from polyacrylonitrile fiber by a facile two-step synthesis process i.e. carbonization followed by KOH activation.
Abstract: In this report, nitrogen-doped porous carbons were synthesized from polyacrylonitrile fiber by a facile two-step synthesis process i.e. carbonization followed by KOH activation. Activation temperature and KOH/carbon ratio are two parameters to tune the porosity and surface chemical properties of sorbents. The as-obtained sorbents were carefully characterized. Special attention was paid concerning the change of sorbents' morphology with respect to synthesis conditions. Under the activation temperatures of this study, the sorbents can still retain their fibrous structure when the KOH/carbon mass ratio is 1. Further increasing the KOH amount will destroy the original morphology of polyacrylonitrile fiber. CO2 adsorption performance tests show that a sorbent retaining the fibrous shape possesses the highest CO2 uptake of 3.95 mmol/g at 25°C and 1 bar. Comprehensive investigation found that the mutual effect of narrow microporosity and doped N content govern the CO2 adsorption capacity of these adsorbents. Furthermore, these polyacrylonitrile fiber-derived carbons present multiple outstanding CO2 capture properties such as excellent recyclability, high CO2/N2 selectivity, fast adsorption kinetics, suitable heat of adsorption, and good dynamic adsorption capacity. Hence, nitrogen-doped porous carbons with fibrous structure are promising in CO2 capture.
60 citations
TL;DR: The results showed that the appropriate presence of allicin significantly enhanced the VFA yield and induced the bacteria to produce more signalling molecules and regulate cellular functions, thereby enhancing the microbial adaptive and regulatory capacity to the unfavourable environment.
Abstract: As a frequently used product with antimicrobial activity, consumed allicin might be discharged and concentrated in waste-activated sludge (WAS). However, the influence of allicin (as an exogenous pollutant) on WAS fermentation has not been clearly revealed. This study aimed to disclose the impacts of allicin on volatile fatty acid (VFA) generation during WAS fermentation. The results showed that the appropriate presence of allicin (10 mg/g TSS) significantly enhanced the VFA yield (1894 versus 575 mg COD/L in the control) with increased acetate proportion (24.3%). Further exploration found that allicin promoted WAS solubilization, hydrolysis and acidification simultaneously. Metagenomic analysis revealed that the key genes involved in extracellular hydrolysis metabolism (i.e., CAZymes), membrane transport (i.e., gtsA and ytfT), substrate metabolism (i.e., yhdR and pfkC) and fatty acid synthesis (i.e., accA and accD) were all highly expressed. Allicin also induced the bacteria to produce more signalling molecules and regulate cellular functions, thereby enhancing the microbial adaptive and regulatory capacity to the unfavourable environment. Moreover, the variations in fermentative microbes and their contributions to the upregulation of functional genes (i.e., ytfR, gltL, INV, iolD and pflD) for VFA generation were disclosed. Overall, the simultaneous stimulation of functional microbial abundances and metabolic activities contributed to VFA production in allicin-conditioned reactors.
56 citations
TL;DR: In this article , a review summarises the recent works on ACM-based composites in photocatalysis, focusing on the properties of surface and layered structure, elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM, i.e., type 1:1 and type 2:1.
Abstract: Aluminosilicate clay mineral (ACM) is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring. In past two decades, in-depth understanding on unique layered structure and abundant surface properties endows ACM in the emerging research and application fields. In field of solar-chemical energy conversion, ACM has been widely used to support various semiconductor photocatalysts, forming the composites and achieving efficient conversion of reactants under sunlight irradiation. To date, classic ACM such as kaolinite and montmorillonite, loaded with semiconductor photocatalysts has been widely applied in photocatalysis. This review summaries the recent works on ACM-based composites in photocatalysis. Focusing on the properties of surface and layered structure, we elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM, i.e., type 1:1 and type 2:1. Not only large surface area and active surface hydroxyl group assist the substrate adsorption, but also the layered structure provides more space to enlarge the application of ACM-based photocatalysts. Besides, we overview the modifications on ACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process. This review could inspire more upcoming design and synthesis for ACM-based photocatalysts, leading this kind of economic and eco-friendly materials for more practical application in the future.
56 citations
TL;DR: In this article , the impact of allicin on volatile fatty acid (VFA) generation during waste-activated sludge (WAS) fermentation has been investigated, and the results showed that the appropriate presence of 10 mg/g TSS significantly enhanced the VFA yield (1894 versus 575 mg COD/L in the control).
Abstract: As a frequently used product with antimicrobial activity, consumed allicin might be discharged and concentrated in waste-activated sludge (WAS). However, the influence of allicin (as an exogenous pollutant) on WAS fermentation has not been clearly revealed. This study aimed to disclose the impacts of allicin on volatile fatty acid (VFA) generation during WAS fermentation. The results showed that the appropriate presence of allicin (10 mg/g TSS) significantly enhanced the VFA yield (1894 versus 575 mg COD/L in the control) with increased acetate proportion (24.3%). Further exploration found that allicin promoted WAS solubilization, hydrolysis and acidification simultaneously. Metagenomic analysis revealed that the key genes involved in extracellular hydrolysis metabolism (i.e., CAZymes), membrane transport (i.e., gtsA and ytfT), substrate metabolism (i.e., yhdR and pfkC) and fatty acid synthesis (i.e., accA and accD) were all highly expressed. Allicin also induced the bacteria to produce more signalling molecules and regulate cellular functions, thereby enhancing the microbial adaptive and regulatory capacity to the unfavourable environment. Moreover, the variations in fermentative microbes and their contributions to the upregulation of functional genes (i.e., ytfR, gltL, INV, iolD and pflD) for VFA generation were disclosed. Overall, the simultaneous stimulation of functional microbial abundances and metabolic activities contributed to VFA production in allicin-conditioned reactors.
50 citations
TL;DR: The effects of different chemical oxygen demand (COD) concentrations on the anammox granular sludge with Bamboo Charcoal (BC) addition were evaluated in UASB reactor and it was interesting to note that BC addition greatly enriched the related functional genes of denitrification and anamm ox.
Abstract: The effects of different chemical oxygen demand (COD) concentrations on the anammox granular sludge with Bamboo Charcoal (BC) addition were evaluated in UASB reactor. The results showed that the average total nitrogen (TN) removal efficiency was reduced from 85.9% to 81.4% when COD concentration was increased from 50 to 150 mg/L. However, the TN removal efficiency of BC addition reactors was dramatically 3.1%–6.4% higher than that without BC under different COD concentrations. The average diameter of granular sludge was 0.13 mm higher than that without BC. The settling velocity was increased by elevated COD concentration, while the EPS and VSS/SS were increased with BC addition. The high-throughput Miseq sequencing analyses revealed that the bacterial diversity and richness were decreased under COD addition, and the Planctomycetes related to anammox bacteria were Candidatus Brocadia and Candidatus Kuenenia. The Metagenomic sequencing indicated that the abundance of denitrification related functional genes all increased with elevated COD, while the abundance of anammox related functional genes of decreased. The functional genes related to anammox was hydrazine synthase encoding genes (hzsA, hzsB and hzsB). The average relative abundance of hzs genes in the reactor with BC addition was higher than the control at COD concentrations of 50 mg/L and 150 mg/L. The functional genes of denitrification mediated by BC were higher than those without BC throughout the operation phase. It is interesting to note that BC addition greatly enriched the related functional genes of denitrification and anammox.
48 citations
TL;DR: This study well demonstrates that BC-nZVI has been emerged as a potential technology for the remediation of multiple heavy metals in soil.
Abstract: Risk associated with heavy metals in soil has been received widespread attention. In this study, a porous biochar supported nanoscale zero-valent iron (BC-nZVI) was applied to immobilize cadmium (Cd) and lead (Pb) in clayey soil. Experiment results indicated that the immobilization of Cd or Pb by BC-nZVI process was better than that of BC or nZVI process, and about 80% of heavy metals immobilization was obtained in BC-nZVI process. Addition of BC-nZVI could increase soil pH and organic matter (SOM). Cd or Pb immobilization was inhibited with coexisting organic compound 2,4-dichlorophenol (2,4-DCP), but 2,4-DCP could be removed in a simultaneous manner with Cd or Pb immobilization at low concentration levels. Simultaneous immobilization of Cd and Pb was achieved in BC-nZVI process, and both Cd and Pb availability significantly decreased. Stable Cd species inculding Cd(OH)2, CdCO3 and CdO were formed, whereas stable Pb species such as PbCO3, PbO and Pb(OH)2 were produced with BC-nZVI treatment. Simultaneous immobilization mechanism of Cd and Pb in soil by BC-nZVI was thereby proposed. This study well demonstrates that BC-nZVI has been emerged as a potential technology for the remediation of multiple heavy metals in soil.
44 citations
TL;DR: In this paper , the effects of different chemical oxygen demand (COD) concentrations on the anammox granular sludge with Bamboo Charcoal (BC) addition were evaluated in UASB reactor.
Abstract: The effects of different chemical oxygen demand (COD) concentrations on the anammox granular sludge with Bamboo Charcoal (BC) addition were evaluated in UASB reactor. The results showed that the average total nitrogen (TN) removal efficiency was reduced from 85.9% to 81.4% when COD concentration was increased from 50 to 150 mg/L. However, the TN removal efficiency of BC addition reactors was dramatically 3.1%–6.4% higher than that without BC under different COD concentrations. The average diameter of granular sludge was 0.13 mm higher than that without BC. The settling velocity was increased by elevated COD concentration, while the EPS and VSS/SS were increased with BC addition. The high-throughput Miseq sequencing analyses revealed that the bacterial diversity and richness were decreased under COD addition, and the Planctomycetes related to anammox bacteria were Candidatus Brocadia and Candidatus Kuenenia . The Metagenomic sequencing indicated that the abundance of denitrification related functional genes all increased with elevated COD, while the abundance of anammox related functional genes of decreased. The functional genes related to anammox was hydrazine synthase encoding genes ( hzsA, hzsB and hzsB ). The average relative abundance of hzs genes in the reactor with BC addition was higher than the control at COD concentrations of 50 mg/L and 150 mg/L. The functional genes of denitrification mediated by BC were higher than those without BC throughout the operation phase. It is interesting to note that BC addition greatly enriched the related functional genes of denitrification and anammox.
TL;DR: Li et al. as discussed by the authors analyzed heavy metal pollution from a macroscopic point of view, and found that Pb, Zn, As and Cd were common contaminants that were present in soils with extremely high concentrations.
Abstract: Smelting activities pose serious environmental problems due to the local and regional heavy metal pollution in soils they cause. It is therefore important to understand the pollution situation and its source in the contaminated soils. In this paper, data on heavy metal pollution in soils resulting from Pb/Zn smelting (published in the last 10 years) in China was summarized. The heavy metal pollution was analyzed from a macroscopic point of view. The results indicated that Pb, Zn, As and Cd were common contaminants that were present in soils with extremely high concentrations. Because of the extreme carcinogenicity, genotoxicity and neurotoxicity that heavy metals pose, remediation of the soils contaminated by smelting is urgently required. The primary anthropogenic activities contributing to soil pollution in smelting areas and the progressive development of accurate source identification were performed. Due to the advantages of biominerals, the potential of biomineralization for heavy metal contaminated soils was introduced. Furthermore, the prospects of geochemical fraction analysis, combined source identification methods as well as several optimization methods for biomineralization are presented, to provide a reference for pollution investigation and remediation in smelting contaminated soils in the future.
TL;DR: A systematic review of biosensor applications in the identification of foodborne and waterborne microorganisms based on research articles identified in the Pubmed, ScienceDirect, and Scopus search engines covering the period from January 2010 to December 2019.
Abstract: Biosensors for sensitive and specific detection of foodborne and waterborne pathogens are particularly valued for their portability, usability, relatively low cost, and real-time or near real-time response. Their application is widespread in several domains, including environmental monitoring. The main limitation of currently developed biosensors is a lack of sensitivity and specificity in complex matrices. Due to increased interest in biosensor development, we conducted a systematic review, complying with the PRISMA guidelines, covering the period from January 2010 to December 2019. The review is focused on biosensor applications in the identification of foodborne and waterborne microorganisms based on research articles identified in the Pubmed, ScienceDirect, and Scopus search engines. Efforts are still in progress to overcome detection limitations and to provide a rapid detection system which will safeguard water and food quality. The use of biosensors is an essential tool with applicability in the evaluation and monitoring of the environment and food, with great impact in public health.
TL;DR: Wang et al. as mentioned in this paper measured the concentrations of Cr, Fe, Ni, Cu, Zn, Cd, Pb and Hg in 87 fish samples within 12 economic fish species collected from the Dongting Lake, the second largest freshwater lake in China.
Abstract: We measured the concentrations of Cr, Fe, Ni, Cu, Zn, Cd, Pb and Hg, and the stable isotope ratios (δ13C and δ15N) in 87 fish samples within 12 economic fish species collected from the Dongting Lake, the second largest freshwater lake in China. With few exceptions in concentration of Cr, most of fish species showed lower concentrations of the 8 metals than legislation thresholds. Piscivorous fishes had significantly higher values of δ15N (possessing higher trophic level) and metal concentrations than planktivorous and herbivorous fishes. Moreover, demersal fishes showed higher concentrations of Cu, Zn, Cd and Pb than pelagic and benthopelagic fishes. We found positive correlations between concentrations of Fe, Pb and Hg and δ15N ratio, confirming the biomagnification of the three metals through trophic transfer. In contrast, fishes showed clear growth dilution effect for Ni, Zn, Cu, Pb and Hg, indicated by the negative correlations between their concentrations and fish weight or length. Multiple regression analysis demonstrated that growth dilution and biomagnification effects simultaneously governed the metal concentrations in fish muscle, and the two effects' importance varied among different metals. The human health risk assessment indicated that all 8 metals gave target hazard quotient (THQ) values
TL;DR: In this paper, the effects of urbanization on phytoplankton community structure and function in a subtropical river at watershed scale in southeast China over 6 years were explored.
Abstract: Urbanization often exerts multiple effects on aquatic and terrestrial organisms, including changes in biodiversity, species composition and ecosystem functions. However, the impacts of urbanization on river phytoplankton in subtropical urbanizing watersheds remain largely unknown. Here, we explored the effects of urbanization on phytoplankton community structure (i.e., biomass, community composition and diversity) and function (i.e., resource use efficiency) in a subtropical river at watershed scale in southeast China over 6 years. A total of 318 phytoplankton species belonging into 120 genera and 7 phyla were identified from 108 samples. Bacillariophyta biomass showed an increasing trend with increasing urbanization level. The phytoplankton community shifted from Chlorophyta dominance in rural upstream waters to Bacillariophyta dominance in urbanized downstream waters. Furthermore, phytoplankton diversity and resource use efficiency (RUE = phytoplankton biomass/total phosphorus) were significantly decreased with increasing urbanization level from upstream to downstream. Phytoplankton RUE exhibited a significant positive correlation with species richness, but a negative correlation with phytoplankton evenness. The variation in environmental factors (turbidity, total nitrogen, NH4+-N, total phosphorus, PO43−-P and percentage urbanized area) was significantly correlated with phytoplankton diversity and RUE. Overall, our results revealed the influence of urbanization on phytoplankton community structure and ecosystem function was due to its altering the environmental conditions. Therefore, human-driven urbanization may play crucial roles in shaping the structure and function of phytoplankton communities in subtropical rivers, and the mechanism of this process can provide important information for freshwater sustainable uses, watershed management and conservation.
TL;DR: Wang et al. as mentioned in this paper measured the concentrations of Cr, Fe, Ni, Cu, Zn, Cd, Pb and Hg in 87 fish samples within 12 economic fish species collected from the Dongting Lake, the second largest freshwater lake in China.
Abstract: We measured the concentrations of Cr, Fe, Ni, Cu, Zn, Cd, Pb and Hg, and the stable isotope ratios (δ13C and δ15N) in 87 fish samples within 12 economic fish species collected from the Dongting Lake, the second largest freshwater lake in China. With few exceptions in concentration of Cr, most of fish species showed lower concentrations of the 8 metals than legislation thresholds. Piscivorous fishes had significantly higher values of δ15N (possessing higher trophic level) and metal concentrations than planktivorous and herbivorous fishes. Moreover, demersal fishes showed higher concentrations of Cu, Zn, Cd and Pb than pelagic and benthopelagic fishes. We found positive correlations between concentrations of Fe, Pb and Hg and δ15N ratio, confirming the biomagnification of the three metals through trophic transfer. In contrast, fishes showed clear growth dilution effect for Ni, Zn, Cu, Pb and Hg, indicated by the negative correlations between their concentrations and fish weight or length. Multiple regression analysis demonstrated that growth dilution and biomagnification effects simultaneously governed the metal concentrations in fish muscle, and the two effects' importance varied among different metals. The human health risk assessment indicated that all 8 metals gave target hazard quotient (THQ) values < 1.0, i.e., the estimated daily intake (EDI) of metals did not exceed the oral reference dose (RfD), indicating a safe consumption of these fish species for consumer. Our study provides comprehensive approaches to better understand the determining processes and potential risk of heavy metals in freshwater lake fishes.
TL;DR: In this article , the effects of urbanization on phytoplankton community structure and function in a subtropical river at watershed scale in southeast China over 6 years were explored.
Abstract: Urbanization often exerts multiple effects on aquatic and terrestrial organisms, including changes in biodiversity, species composition and ecosystem functions. However, the impacts of urbanization on river phytoplankton in subtropical urbanizing watersheds remain largely unknown. Here, we explored the effects of urbanization on phytoplankton community structure (i.e., biomass, community composition and diversity) and function (i.e., resource use efficiency) in a subtropical river at watershed scale in southeast China over 6 years. A total of 318 phytoplankton species belonging into 120 genera and 7 phyla were identified from 108 samples. Bacillariophyta biomass showed an increasing trend with increasing urbanization level. The phytoplankton community shifted from Chlorophyta dominance in rural upstream waters to Bacillariophyta dominance in urbanized downstream waters. Furthermore, phytoplankton diversity and resource use efficiency (RUE = phytoplankton biomass/total phosphorus) were significantly decreased with increasing urbanization level from upstream to downstream. Phytoplankton RUE exhibited a significant positive correlation with species richness, but a negative correlation with phytoplankton evenness. The variation in environmental factors (turbidity, total nitrogen, NH4+-N, total phosphorus, PO43--P and percentage urbanized area) was significantly correlated with phytoplankton diversity and RUE. Overall, our results revealed the influence of urbanization on phytoplankton community structure and ecosystem function was due to its altering the environmental conditions. Therefore, human-driven urbanization may play crucial roles in shaping the structure and function of phytoplankton communities in subtropical rivers, and the mechanism of this process can provide important information for freshwater sustainable uses, watershed management and conservation.
TL;DR: In this article , the authors comprehensively review the current scenario of OPs pollution, their toxicity (at a molecular level), and the recent advancements in biotechnology (modified biocatalytic systems) for detection, decontamination, and bioremediation of OP-pesticides in polluted environments.
Abstract: Organophosphates (OPs) are an integral part of modern agriculture; however, due to overexploitation, OPs pesticides residues are leaching and accumulating in the soil, and groundwater contaminated terrestrial and aquatic food webs. Acute exposure to OPs could produce toxicity in insects, plants, animals, and humans. OPs are known for covalent inhibition of acetylcholinesterase enzyme in pests and terrestrial/aquatic organisms, leading to nervous, respiratory, reproductive, and hepatic abnormalities. OPs pesticides also disrupt the growth-promoting machinery in plants by inhibiting key enzymes, permeability, and trans-cuticular diffusion, which is crucial for plant growth. Excessive use of OPs, directly/indirectly affecting human/environmental health, raise a thoughtful global concern. Developing a safe, reliable, economical, and eco-friendly methods for removing OPs pesticides from the environment is thus necessary. Bioremediation techniques coupled with microbes or microbial-biocatalysts are emerging as promising antidotes for OPs pesticides. Here, we comprehensively review the current scenario of OPs pollution, their toxicity (at a molecular level), and the recent advancements in biotechnology (modified biocatalytic systems) for detection, decontamination, and bioremediation of OP-pesticides in polluted environments. Furthermore, the review focuses on onsite applications of OPs degrading enzymes (immobilizations/biosensors/others), and it also highlights remaining challenges with future approaches.
TL;DR: 30 shallows freshwater lakes in the eastern plain of China were selected to measure dissolved N2 and Ar concentrations through N2: Ar method using a membrane inlet mass spectrometer to quantify the nitrogen fixation capacities and investigate whether the temperature and water residence time have a great impact on nitrogen fixation.
Abstract: Eutrophication and harmful cyanobacterial blooms threaten water resources all over the world. There is a great controversy about controlling only phosphorus or controlling both nitrogen and phosphorus in the management of lake eutrophication. The primary argument against the dual nutrients control of eutrophication is that nitrogen fixation can compensate the nitrogen deficits. Thus, it is of great necessary to study the factors that can significantly affect the nitrogen fixation. Due to the difference of climate and human influence, the water quality of different lakes (such as water temperature, N:P ratio and water residence time) is also quite different. Numerous studies have reported that the low N:P ratio can intensify the nitrogen fixation capacities. However, the effects of temperature and water residence time on the nitrogen fixation remain unclear. Thus, 30 shallows freshwater lakes in the eastern plain of China were selected to measure dissolved N2 and Ar concentrations through N2: Ar method using a membrane inlet mass spectrometer to quantify the nitrogen fixation capacities and investigate whether the temperature and water residence time have a great impact on nitrogen fixation. The results have shown that the short lake water residence time can severely inhibit the nitrogen fixation capacities through inhibiting the growth of nitrogen-fixing cyanobacteria, changing the N:P ratio and resuspending the solids from sediments. Similarly, lakes with low water temperature also have a low nitrogen fixation capacity, suggesting that controlling nitrogen in such lakes is feasible if the growth of cyanobacteria is limited by nitrogen.
TL;DR: In this paper, the concentrations and distributions of legacy and novel per-and perfluoroalkyl substances (PFAS) in topsoil samples from different functional areas in Tianjin were comprehensively investigated.
Abstract: Soil is a major sink for per- and perfluoroalkyl substances (PFAS), wherein PFAS may be transferred through the food chain to predators at upper trophic levels, which poses a threat to human health. Herein, the concentrations and distributions of legacy and novel PFAS in topsoil samples from different functional areas in Tianjin were comprehensively investigated. Seventeen PFAS congeners were identified, with concentrations ranging from 0.21 ng/g to 5.35 ng/g, with a mean concentration of 1.25 ng/g. The main PFAS in the topsoil was perfluorooctanoic acid (PFOA). 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA; C8) were the major sources (43.4%), followed by food packaging as well as coating materials (25.5%). In addition, Spearman correlation analysis and the structural equation model showed that population density significantly impacted the PFAS distribution in the topsoil of Tianjin.
TL;DR: The prepared green metal-free 3D macroscopic N-doped porous carbon nanosheets (NPCN) showed high adsorption capacity of tetracycline (TC) and excellent persulfate (PS) activation ability, especially when calcined at 700 °C (nPCN-700).
Abstract: Recently, metal-based carbon materials have been verified to be an effective persulfate activator, but secondary pollution caused by metal leaching is inevitable. Hence, a green metal-free 3D macroscopic N-doped porous carbon nanosheets (NPCN) was synthesized successfully. The obtained NPCN showed high adsorption capacity of tetracycline (TC) and excellent persulfate (PS) activation ability, especially when calcined at 700 °C (NPCN-700). The maximum adsorption capacity of NPCN-700 was 121.51 mg/g by H-bonds interactions. Moreover, the adsorption process followed pseudo-second-order kinetics model and Langmuir adsorption isotherm. The large specific surface area (365.27 mg/g) and hierarchical porous structure of NPCN-700 reduced the mass transfer resistance and increased the adsorption capacity. About 96.39% of TC was removed after adding PS. The effective adsorption of the catalyst greatly shortened the time for the target organic molecules to migrate to the catalyst. Moreover, the NPCN-700 demonstrated high reusability with the TC removal rate of 80.23% after 4 cycles. Quenching experiment and electron paramagnetic resonance (EPR) test confirmed the non-radical mechanism dominated by 1O2. More importantly, the C = O groups, defects and Graphitic N acted as active sites to generate 1O2. Correspondingly, electrochemical measurement revealed the direct electron transfer pathway of TC degradation. Finally, multiple degradation intermediates were recognized by the LC-MS measurement and three possible degradation pathways were proposed. Overall, the prepared NPCN had excellent application prospects for removal of antibiotics due to its remarkable adsorption and catalytic degradation capabilities.
TL;DR: In this paper , a green metal-free 3D macroscopic N-doped porous carbon nanosheets (NPCN-700) was synthesized successfully, and the obtained NPCN showed high adsorption capacity of tetracycline (TC) and excellent persulfate (PS) activation ability, especially when calcined at 700 °C.
Abstract: Recently, metal-based carbon materials have been verified to be an effective persulfate activator, but secondary pollution caused by metal leaching is inevitable. Hence, a green metal-free 3D macroscopic N-doped porous carbon nanosheets (NPCN) was synthesized successfully. The obtained NPCN showed high adsorption capacity of tetracycline (TC) and excellent persulfate (PS) activation ability, especially when calcined at 700 °C (NPCN-700). The maximum adsorption capacity of NPCN-700 was 121.51 mg/g by H-bonds interactions. Moreover, the adsorption process followed pseudo-second-order kinetics model and Langmuir adsorption isotherm. The large specific surface area (365.27 mg/g) and hierarchical porous structure of NPCN-700 reduced the mass transfer resistance and increased the adsorption capacity. About 96.39% of TC was removed after adding PS. The effective adsorption of the catalyst greatly shortened the time for the target organic molecules to migrate to the catalyst. Moreover, the NPCN-700 demonstrated high reusability with the TC removal rate of 80.23% after 4 cycles. Quenching experiment and electron paramagnetic resonance (EPR) test confirmed the non-radical mechanism dominated by 1O2. More importantly, the C = O groups, defects and Graphitic N acted as active sites to generate 1O2. Correspondingly, electrochemical measurement revealed the direct electron transfer pathway of TC degradation. Finally, multiple degradation intermediates were recognized by the LC-MS measurement and three possible degradation pathways were proposed. Overall, the prepared NPCN had excellent application prospects for removal of antibiotics due to its remarkable adsorption and catalytic degradation capabilities.
TL;DR: In this article , the concentrations and distributions of legacy and novel per-and perfluoroalkyl substances (PFAS) in topsoil samples from different functional areas in Tianjin were comprehensively investigated.
Abstract: Soil is a major sink for per- and perfluoroalkyl substances (PFAS), wherein PFAS may be transferred through the food chain to predators at upper trophic levels, which poses a threat to human health. Herein, the concentrations and distributions of legacy and novel PFAS in topsoil samples from different functional areas in Tianjin were comprehensively investigated. Seventeen PFAS congeners were identified, with concentrations ranging from 0.21 ng/g to 5.35 ng/g, with a mean concentration of 1.25 ng/g. The main PFAS in the topsoil was perfluorooctanoic acid (PFOA). 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA; C8) were the major sources (43.4%), followed by food packaging as well as coating materials (25.5%). In addition, Spearman correlation analysis and the structural equation model showed that population density significantly impacted the PFAS distribution in the topsoil of Tianjin.
TL;DR: Wang et al. as mentioned in this paper demonstrated the significance of wastewater-based epidemiology in continuous surveillance of SARS-CoV-2 at the community level, even when the COVID-19 prevalence is low.
Abstract: Wastewater-based epidemiology (WBE) has emerged as an effective environmental surveillance tool in monitoring fecal-oral pathogen infections within a community. Congruently, SARS-CoV-2, the etiologic agent of COVID-19, has been demonstrated to infect the gastrointestinal tissues, and be shed in feces. In the present study, SARS-CoV-2 RNA was concentrated from wastewater, sludge, surface water, ground water, sediment, and soil samples of municipal and hospital wastewater systems and related environments in Wuhan during the COVID-19 middle and low risk periods, and the viral RNA copies quantified using reverse transcription quantitative polymerase chain reaction (RT-qPCR). From the findings of this study, during the middle risk period, one influent sample and three secondary effluents collected from waste water treatment plant 2, as well as two samples from Jinyintan Hospital wastewater system influent were SARS-CoV-2 RNA positive. One sludge sample collected from Guanggu Branch of Tongji Hospital, which was obtained during the low risk period, was also positive for SARS-CoV-2 RNA. These study findings demonstrate the significance of WBE in continuous surveillance of SARS-CoV-2 at the community level, even when the COVID-19 prevalence is low. Overall, this study can be used as an important reference for contingency management of wastewater treatment plants and COVID-19 prevention and control departments of Wuhan.
TL;DR: In this article, a synergistic system with PRB and electrokinetics (PRB-EK) was established and applied for the efficient removal of Cr(VI)-contaminated groundwater.
Abstract: Although widely used in permeation reaction barrier (PRB) for strengthening the removal of various heavy metals, zero-valent iron (ZVI) is limited by various inherent drawbacks, such as easy passivation and poor electron transfer. As a solution, a synergistic system with PRB and electrokinetics (PRB-EK) was established and applied for the efficient removal of Cr(VI)-contaminated groundwater. As the filling material of PRB, ZVI/Fe3O4/activated carbon (ZVI/Fe3O4/AC) composites were synthesized by ball milling and thermal treatment. A series of continuous flow column experiments and batch tests was conducted to evaluate the removal efficiency of Cr(VI). Results showed that the removal efficiency of Cr(VI) remained above 93% even when the bed volume (BV) reached 2000 under the operational parameters (iron/AC mass ratio, 2:1; current, 5 mA). The mechanism of Cr(VI) removal by the PRB-EK system was revealed through field emission scanning electron microscopy images, X-ray diffraction, X-ray photoelectron spectroscopy, Fe2+ concentration, and redox potential (Eh) values. The key in Cr(VI) reduction was the Fe2+/Fe3+ cycle driven by the surface microelectrolysis of the composites. The application of an externally supplied weak direct current maintained the redox process by enhancing the electron transfer capability of the system, thereby prolonging the column lifetime. Cr(VI) chemical speciation was determined through sequential extraction, verifying the stability and safety of the system. These findings provide a scientific basis for PRB design and the in-situ remediation of Cr(VI)-contaminated groundwater.
TL;DR: In this article, a series of Co-Mn mixed oxide catalyst supported on a cordierite monolith was facilely synthesized by ultrasonic impregnation and its catalytic performance was evaluated in the combustion of toluene, ethyl acetate and its mixture.
Abstract: A series of Co-Mn mixed oxide catalyst supported on a cordierite monolith was facilely synthesized by ultrasonic impregnation. Its catalytic performance was evaluated in the combustion of toluene, ethyl acetate and its mixture. It was observed that with incorporating Mn into Co3O4, the formation of solid solution with spinel structure could significantly improve the catalytic activity of pure phase Co3O4. And the monolithic Co0.67Mn0.33Ox catalyst showed the best catalytic performance in the catalytic oxidation of toluene and ethyl acetate which could be completely oxidized at 220 and 180°C respectively under the reaction velocity (WHSV) about 45,000 mL/(g•hr) and pollutant concentration of 500 ppmV. The total conversion temperature of the VOCs mixture was at 230°C (500 ppmV toluene and 500 ppmV ethyl acetate) and determined by the temperature at which the most difficult molecule was oxidized. The excellent catalytic performance of monolithic Co0.67Mn0.33Ox was attributed to the higher content of Mn3+, Co3+, surface adsorbed oxygen and better redox ability. The prepared catalyst showed the good mechanical stability, reaction stability, and good adaptability to different reaction conditions.
TL;DR: Findings from the present study demonstrated that the SC-nZVI@BC exhibited excellent removal efficiency toward Cr(Ⅵ) with an improved synergistic characteristic by SC and BC.
Abstract: Sodium citrate (SC) is a widely-used food and industrial additive with the properties of complexation and microbial degradation. In the present study, nano-zero-valent iron reaction system (SC-nZVI@BC) was successfully established by modifying nanoscale zero-valent iron (nZVI) with SC and biochar (BC), and was employed to remove Cr(Ⅵ) from aqueous solutions. The nZVI, SC-nZVI and SC-nZVI@BC were characterized and compared using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyses (TGA), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that nZVI was successfully loaded on the biochar, and both the agglomeration and surface passivation problems of nanoparticles were well resolved. The dosage of SC, C:Fe, initial pH and Cr(Ⅵ) concentration demonstrated direct effects on the removal efficiency. The maximum Cr(Ⅵ) removal rate and the removal capacity within 60 min were 99.7% and 199.46 mg/g, respectively (C:Fe was 1:1, SC dosage was 1.12 mol.%, temperature was 25°C, pH = 7, and the original concentration of Cr(Ⅵ) was 20 mg/L). The reaction confirmed to follow the pseudo-second-order reaction kinetics, and the order of the reaction rate constant k was as follows: SC-nZVI@BC > nZVI@BC > SC-nZVI > nZVI. In addition, the mechanism of Cr(Ⅵ) removal by SC-nZVI@BC mainly involved adsorption, reduction and co-precipitation, and the reduction of Cr(Ⅵ) to Cr(Ⅲ) by nano Fe0 played a vital role. Findings from the present study demonstrated that the SC-nZVI@BC exhibited excellent removal efficiency toward Cr(Ⅵ) with an improved synergistic characteristic by SC and BC.
TL;DR: The new adsorbents introduced here were high adsorption activity, ease of fabrication, high scalability, good chemical stability, great repeatability and abundant and cheap supply, which were highly attractive for wastewater treatment.
Abstract: Toxic heavy metal ions, valuable noble metal ions and organic dyes are significant concerns in wastewater treatment. In this work, MoO3 nanobelts (MoO3 NBs) prepared by solvothermal method and MoS2 nanoarrays (MoS2 NAs) constructed using MoO3 NBs precursor were proposed to effectively remove heavy/noble metal ions and organic dyes, such as Pb(II), Au(III) and Methylene Blue (MB). The two adsorbents exhibited the excellent adsorption capacity towards Pb(II), Au(III) and MB. The maximum removal capacity of Pb(II) and MB on MoO3 NBs was 684.93 mg/g and 1408 mg/g, respectively, whereas that of Au(III) and MB on MoS2 NAs was 1280.2 mg/g and 768 mg/g, respectively. Furthermore, the thermodynamic parameters were calculated from the temperature-dependent curves, suggesting that the removal of Pb(II) and Au(III) on both adsorbents was spontaneous and endothermic. The new adsorbents introduced here were high adsorption activity, ease of fabrication, high scalability, good chemical stability, great repeatability and abundant and cheap supply, which were highly attractive for wastewater treatment.
TL;DR: In this paper , 30 shallows freshwater lakes in the eastern plain of China were selected to measure dissolved N2 and Ar concentrations through N2:Ar method using a membrane inlet mass spectrometer to quantify the nitrogen fixation capacities and investigate whether the temperature and water residence time have a great impact on nitrogen fixation.
Abstract: Eutrophication and harmful cyanobacterial blooms threaten water resources all over the world. There is a great controversy about controlling only phosphorus or controlling both nitrogen and phosphorus in the management of lake eutrophication. The primary argument against the dual nutrients control of eutrophication is that nitrogen fixation can compensate the nitrogen deficits. Thus, it is of great necessary to study the factors that can significantly affect the nitrogen fixation. Due to the difference of climate and human influence, the water quality of different lakes (such as water temperature, N:P ratio and water residence time) is also quite different. Numerous studies have reported that the low N:P ratio can intensify the nitrogen fixation capacities. However, the effects of temperature and water residence time on the nitrogen fixation remain unclear. Thus, 30 shallows freshwater lakes in the eastern plain of China were selected to measure dissolved N2 and Ar concentrations through N2: Ar method using a membrane inlet mass spectrometer to quantify the nitrogen fixation capacities and investigate whether the temperature and water residence time have a great impact on nitrogen fixation. The results have shown that the short lake water residence time can severely inhibit the nitrogen fixation capacities through inhibiting the growth of nitrogen-fixing cyanobacteria, changing the N:P ratio and resuspending the solids from sediments. Similarly, lakes with low water temperature also have a low nitrogen fixation capacity, suggesting that controlling nitrogen in such lakes is feasible if the growth of cyanobacteria is limited by nitrogen.
TL;DR: In this paper , a review examines the most recent breakthroughs in various techniques for modifying MOFs in order to improve their efficiency of photocatalytic CO2 reduction and discusses the existing challenges and future prospects of MOFs as photocatalyst.
Abstract: Photocatalytic CO2 reduction is an appealing strategy for mitigating the environmental effects of greenhouse gases while simultaneously producing valuable carbon-neutral fuels. Numerous attempts have been made to produce effective and efficient photocatalysts for CO2 reduction. In contrast, the selection of competitive catalysts continues to be a substantial hindrance and a considerable difficulty in the development of photocatalytic CO2 reduction. It is vital to emphasize different techniques for building effective photocatalysts to improve CO2 reduction performance in order to achieve a long-term sustainability. Metal-organic frameworks (MOFs) are recently emerging as a new type of photocatalysts for CO2 reduction due to their excellent CO2 adsorption capability and unique structural characteristics. This review examines the most recent breakthroughs in various techniques for modifying MOFs in order to improve their efficiency of photocatalytic CO2 reduction. The advantages of MOFs using as photocatalysts are summarized, followed by different methods for enhancing their effectiveness for photocatalytic CO2 reduction via partial ion exchange of metal clusters, design of bimetal clusters, the modification of organic linkers, and the embedding of metal complexes. For integrating MOFs with semiconductors, metallic nanoparticles (NPs), and other materials, a number of different approaches have been also reviewed. The final section of this review discusses the existing challenges and future prospects of MOFs as photocatalysts for CO2 reduction. Hopefully, this review can stimulate intensive research on the rational design and development of more effective MOF-based photocatalysts for visible-light driven CO2 conversion.