Showing papers in "Environmental Nanotechnology, Monitoring and Management in 2017"

Heavy metal contamination in surface water and sediment of the Meghna River, Bangladesh

Abstract: Globally alarming ten heavy metal (Zn, Al, Cd, Pb, Cu, Ni, Fe, Mn, Cr, Co) concentrations were estimated in surface water and sediment of the Meghna River in Bangladesh from September 2015 to March 2016. Heavy metals were analyzed by Atomic Absorption Spectrophotometer (AAS). Results indicated that, all the metals in water were found below the safe limit of drinking water standard of WHO (1993) and EU (1998) with the exclusion of Fe, Ni and Al. In sediment, all the trace metals were recorded below the limit compared to other scientific results. For three seasons at two sampling points no significant difference in heavy metals was founded at the significance level (p > 0.05). Multivariate statistical analyses such as principal component analysis and correlation matrix disclosed prevalent anthropogenic interferences of Zn, Al, Cd, Pb, Cu, Ni, Fe, Mn, Cr, Co in water and sediment. The very strong positive correlation was recorded between Fe vs Al (0.992), Mn v’s Cu (0.948), Fe vs Mn (0.939), Zn vs Al (0.929), Fe vs Zn (0.920) in water. In sediment, very strong linear relationships were found in Cd vs Zn (0.999), Cd vs Cu (0.998), Zn vs Cu (0.996), Cd vs Ni (0.995), Ni vs Cu (0.994), Ni vs Zn (0.993) etc. at the 0.05 significance level which direct their common origin exclusively from industrial effluents, municipal wastes and agricultural inputs. Necessary steps should be taken to protect this River from pollution and also to reduce the environmental risk.

A review on the visible light active BiFeO3 nanostructures as suitable photocatalyst in the degradation of different textile dyes

Abstract: Different effluents from textile industries which are dumped into the water bodies have been a major concern of the modern world. The uncontrolled discharge of the synthetic textile dyes in water bodies especially have led to serious environmental problems and health hazards. Among the different existing approaches to treat water, photocatalysis is an attractive approach as it uses the inexhaustible and clean solar energy. Considering its ability to absorb in the visible light of solar spectrum, its multiferroic property and its crystal structure, researchers feel BiFeO3 can provide a breakthrough in the treatment of water. In this article, a thorough review is presented on the various attempts done so far on degradation of different synthetic textile dyes solution using BiFeO3 nanostructures.

Nanocellulose based biosorbents for wastewater treatment: Study of isotherm, kinetic, thermodynamic and reusability

Abstract: The advance technology in 21st century has given human ease of life and huge problem in environmental sector. Recently, the improvement on nanomaterial has attracted researchers in the preparation of nanocellulose adsorbents. The stability of nanocellulose as adsorbent also shows good prospects in upgrading scale as regenerative aspects indicates good performance after several adsorption-desorption cycle. This review paper provides a comprehensive review on the use of nanocellulose and its modified forms for the wastewater treatment. Various aspects on the validity of adsorption isotherms and kinetic models as well as theoretical aspects of the thermodynamic of adsorption are also given in this paper. Future perspective on the use of NCC and its modified forms for industrial application is also discussed.

Removal of Mn(II) from water using chemically modified banana peels as efficient adsorbent

Abstract: In this study a novel acrylonitrile grafted cellulosic adsorbent is prepared from bleached banana pulp. Banana peels were hydrolyzed with alkali followed by bleaching with sodium chlorate (NaClO3). The grafting co-polymerization of acrylonitrile onto the bleached pulp was carried out using Fenton’s reagent (Fe+/H2O2) as initiator. The acrylonitrile grafted cellulosic adsorbent was used for Mn(II) removal from aqueous solution. The adsorption of Mn(II) onto grafted banana peels was recorded to be 94%. The adsorption equilibrium is fitted well by Langmuir isotherm model. Owing to high efficiency and low cost, grafted banana peels (GBPs) can be used as effective adsorbent for Mn(II) removal from aqueous solution and industrial waste water.

Liquid phase scavenging of Cd (II) and Cu (II) ions onto novel nanoscale zerovalent manganese (nZVMn): Equilibrium, kinetic and thermodynamic studies

Abstract: Nanostructured zerovalent manganese (nZVMn) was successfully synthesized and characterized by a combination of analytical and spectroscopic techniques nZVMn was utilized in scavenging of Cd (II) and Cu (II) ions from aqueous solution The BET surface area of nZVMn was 1313490 m2/g, adsorption average pore width (1704736 A), BJH Adsorption average pore diameter (185147 A), and pH(pzc) (501) The scavenging process was found to depend on effect of various adsorption physicochemical parameters investigated in batch process The results revealed a fast kinetics for the adsorption systems; the data fitted well to pseudo second-order and the mechanism was governed by pore diffusion confirmed by Bangham model The equilibrium data were tested with Langmuir, Freundlich, Temkin, Dubinin-Raduskevuch (D-R), and Halsey Isotherm models However, equilibrium data were best interpreted by Langmuir and Freundlich isotherm models Both Kinetic and isotherm models were validated by sum of square error (SSE) and non-linear chi-square (χ2) The Langmuir monolayer maximum adsorption capacities of nZVMn for adsorption of Cd2+ and Cu2+ were 11628 mg/g and 18182 mg/g respectively and these superseded several other adsorbents reported The feasibility, spontaneous and endothermic nature of the adsorption process was unraveled from thermodynamics parameters Judging from the desorption index and efficiency, effective desorption of loaded nZVMn was achieved using HCl which is further supported chemisorption mechanism The micrographs of Scanning Electron Microscopy (SEM) before and after adsorption further confirmed the liquid scavenging of the adsorption process This study unraveled the effective adsorption of Cd2+ and Cu2+ onto novel nZVMn from synthetic industrial waste

Photoelectrocatalyst of Fe co-doped N-TiO2/Ti nanotubes: Pesticide degradation of thiamethoxam under UV–visible lights

Abstract: Preparation of titanium dioxide (TiO2) had been carried out by anodizing method that was continued by Nitrogen (N) and Iron (Fe) doping to obtain the Fe-N-TiO2/Ti electrode through sol-gel method. The synthesis of Fe-N-TiO2/Ti by adding NH4Cl as a source of N and Fe(NO3)3 as a source of Fe were prepared by dip-coating technique. The photocurrent response of TiO2/Ti and Fe-N-TiO2/Ti tested in photoelectrocatalyst showed the TiO2/Ti electrode was active in UV light and Fe-N-TiO2/Ti was active in the visible light. The XRD and SEM characterizations result of Fe-N-TiO2/Ti was the forming of anatase crystal and nanotube structure. The FTIR data was indicated the presence of Fe O and Ti N bonds on the wavenumber of 580 cm−1 and 509 cm−1, respectively. The degradation result of thiamethoxam pesticide compound in photoelectrocatalyst showed the TiO2/Ti electrode was active on the UV light irradiation with degradation rate constant 0.0436 min−1 and Fe-N-TiO2/Ti was active in the visible irradiation with the degradation rate constant 0.0580 min−1.

Utilization of nano-alumina and activated charcoal for phosphate removal from wastewater

Abstract: Nano-alumina (NA) and activated charcoal (AC) were compared as adsorbents to remove phosphate from aqueous wastewater. Batch-mode adsorption experiments were carried out to investigate the use of two commercially available adsorbents for the removal of phosphate from synthetic wastewater/solution. Effect of time, adsorbent dosage, pH and temperature was evaluated. Results revealed that maximum phosphate removal of 90.2% was achieved in 120 min at pH 6 using 3.2 g/L of dosage with activated charcoal whereas 100% removal was observed at pH 6 with nano-alumina at 90 min using 1.6 g/L of adsorbent dose The equilibrium data was applied to Langmuir, Freundlich, Tempkin, Dubininin-rudkavich isotherm models. Results revealed that Langmuir isotherm model and pseudo-second order kinetic model were found best fitted for both the adsorbents, having good correlation R2 value (0.999 and 0.938). The value of enthalpy (ΔH) calculated from the thermodynamic parameters revealed that adsorption process is endothermic for both adsorbents. Characterization of both adsorbents done with XRD shows their amorphous and crystalline nature while FTIR of the adsorbents shows the interaction of adsorbent and adsorbate of solution. Morphology of both adsorbent shows the porous nature of adsorbents which indicates their efficiency in wastewater treatment. Study clearly indicates that the removal potential of nano-alumina is more as compared to the activated charcoal.

Silver nanoparticles in soil: Aqueous extraction combined with single-particle ICP-MS for detection and characterization

Abstract: Silver nanoparticles (AgNPs) are used in a growing number of applications and products. Previous studies showed AgNPs can leach from these products to the environment. As a result of AgNPs leaching, sediment, soil and sludge-treated soils may be contaminated with AgNPs. Methods to detect, quantify and characterize AgNPs in soil are urgently needed. This study describes the development and validation of a method for the extraction, quantification and particle size determination of AgNPs in soils. The final method consists of pre-wetting the sample followed by an aqueous extraction, using sonication to re-suspend adsorbed AgNPs, and analysis of the aqueous extract with single particle ICP-MS. Validation of the method showed that the recovery of AgNPs spiked to soil was 44% for sandy soil and 42% for clayey soil. Although this recovery is relatively low, the repeatability and reproducibility values of the particle concentration were within the limits of Horwitz ratio, which makes the method suitable for its purpose. Further, the method concentration detection limit, LODc., is 5 μg kg −1 soil. The developed method can be applied in eco-toxicological and risk-assessments studies for AgNP in the soil environment.

An efficient wastewater treatment approach for a real woolen textile industry using a chemical assisted NF membrane process

Abstract: Woolen textile industries produces a significant high contaminated wastewater streams which have raised environmental concerns as their turbidity (>40 NTU) and COD (>1500 mg/L) are very high. To address their issue, usually a high level of chemical treatment is utilized; however, the addition of such level of chemicals itself creates another issue such as high concentrated sludge. In this study, chemical pretreatment (FeSO4 as coagulant, 400–800 mg/L, pH 6–10,) experiments was employed to reduce COD and turbidity to maximum 200 mg/L and 25 NTU respectively. The chemically assisted nanofiltration (NF) process (operating conditions: 4–8 bar, COD of 50–200 mg/L and pH of 6–10) by using a commercial spiral wound polyamide nano filter (TFC) was used to treat a real woolen textile effluent. Response surface methodology (RSM) was employed to determine the effects of operating parameters. The results showed that the best conditions for the pretreatment process were pH of 8, FeSO4 of 600 mg/L. For the NF process, by increasing pH and pressure, removal efficiency of turbidity and COD increased up to 98%. However, by enhancing the color concentrations, the COD removal efficiency reduced to about 90%. The results demonstrated that NF process at optimum conditions and after chemical pretreatment has an effective efficiency for real textile wastewater treatment.

Sorption of Congo red and reactive blue on biomass and activated carbon derived from biomass modified by ionic liquid

Abstract: Ionic liquid modified sorbent materials derived from peanut shell were prepared and used in the sorption of Congo red (CR) and reactive blue 4 (RB) dyes from aqueous solution. 1-methyl-3-decahexyl imidazolium ionic liquid (IL) was used to modify peanut shell (NS) and activated carbon (AC) from NS, to produce IL modified peanut shell (ILNS) and IL modified AC (ILAC), respectively. The adsorbents were characterised by fourier transform infrared (FTIR), Brunauer−Emmett−Teller (BET), x-ray diffraction (XRD), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). The effects of sorbent dosage, initial solution pH and contact time (min) were evaluated. Adsorption was pH dependent, the modified materials (ILNS and ILAC) showed improved adsorption capacities of 136.4 and 150.0 mg g−1 for CR and 290.0 and 364.4 mg g−1 for RB respectively. Adsorption followed pseudo-second order. Also, adsorption of CR and RB onto ILAC followed the Freundlich isotherm, while ILNS was described by Freundlich and Langmuir.

Removal of cadmium ions from aqueous solutions using TMU-16-NH2 metal organic framework

Abstract: In this research, removal of cadmium from aqueous samples by TMU-16-NH2 metal–organic framework was investigated. In a batch process method, the effect of pH, initial concentration, contact time, temperature and sorbent weight on sorption process was studied. Equilibrium isotherms were fitted by Langmuir and Freundlich equations. The maximum adsorption capacity of Cd(II) was determined 126.6 mg g−1. The metal–organic framework was successfully applied to the quick extraction of trace amounts of Cd(II) ions in water samples. The maximum removal percentage was obtained 98.91 at pH 6.0 and 30 min contact time. The Gibbs free energy ‎(ΔG0‎), the enthalpy (ΔH0), and the entropy (ΔS0) were also calculated from thermodynamic studies. ‎The positive values of ΔH0, ΔS0 and the negative value of ΔG0, confirmed the endothermic nature, randomness and spontaneity of adsorption process.

Macroscopic effects of silver nanoparticles and titanium dioxide on edible plant growth

Abstract: Several products with antimicrobial properties have been developed taking into account human health. Silver, titanium and other metal-based particles can be incorporated into fabrics and plastics in order to prevent microbial growth on their surfaces. The widespread use of these products raises environmental interest, since those metals can lixiviate from the material and reach water and soil, contaminating plants, animals and, at high doses, can cause hazardous effects. Thus, the objective of the present study was to evaluate the possible phytotoxicity of silver nanoparticles adsorbed on fumed silica (AgNp) and titanium dioxide (TiO 2 ) in root growth and morphology of onion ( Allium cepa L.) and seed germination, root growth and morphology of radish ( Raphanus sativus L.). The toxicological behavior of the particles was assayed using standard cytotoxic tests. AgNp and TiO 2 induced root growth inhibition of onion even at a concentration as low as 0.001 mg L −1 . TiO 2 lead to a reduction in root growth of radish while AgNp improved the root growth. The results are in agreement with those found in the literature, with regards to each plant having a specific response to different metal nanoparticles. More studies must be performed to understand the effect of nanoparticles in toxicity of edible plants.

Synthesis of l-cysteine stabilized zero-valent iron (nZVI) nanoparticles for lead remediation from water

Abstract: l -Cysteine ( l -cyst) stabilized zero-valent iron (nZVI) nanoparticles were synthesized by chemical reduction method using ferric chloride as a reducer and l -cyst as a stabilizing agent under nitrogen atmosphere. The l -cyst-nZVI energy band gap of 2.5 eV was obtained using UV absorption spectra. The zeta potential of bare nZVI and l -cyst-nZVI were +24.0 and −35.0 mV, respectively. The surface charge reversal from positive to negative confirmed the l -cyst presence onto the nZVI surface. The biocompatibility study of l -cyst-nZVI was performed using MTT assay on MDCK-2 as model cell lines. Aqueous Pb 2+ sorption studies were conducted at different initial pHs (2.0–7.0), contact time (5–45 min), temperatures (5–45 °C), l -cyst-nZVI dosage (1.0–5.0 g/L) and initial Pb 2+ concentration (10–50 mg/L). Almost 100% of lead was removed from a 50 mg/L lead solution within 25 min. A pseudo-second-order rate equation best described the Pb 2+ sorption kinetics. Separation of exhausted l -cyst-nZVI NPs from aqueous system using a simple magnet was also demonstrated. l -cyst-nZVI nanoparticles may be used to remediate Pb 2+ from aqueous solutions.

Antimicrobial power of Cu/Zn mixed oxide nanoparticles to Escherichia coli

Abstract: The antimicrobial power of a Cu/Zn mixed oxide was probed by viability study against E. coli . A facile, environment friendly synthesis of CuO, ZnO and Cu 0.73 Zn 0.27 O nanoparticles was carried out via hydroxycarbonate precursors and the samples characterized by several techniques. The antimicrobial efficacy of the nanoparticles was, then, probed by two independent growth inhibition essays, the culture methods and the optical density after 4 h, 8 h and 24 h contact time and shows both a time and concentration dependency. Remarkably the Cu 0.73 Zn 0.27 O mixed oxide exhibits the highest antimicrobial activity, with 90% growth inhibition already after 8 h for a dose of 200 μg/mL whereas CuO reaches the same performance only after 24 h and ZnO has, comparatively, only a limited activity.

Analysis of total petroleum hydrocarbons, polycyclic aromatic hydrocarbons and risk assessment of heavy metals in some selected finfishes at Focados Terminal Delta State

Abstract: Edible aquatic fin fishes (I. africana, S. scrombrus, C. saira, T. crocodilus, O. niloticus, T. lepturus and M. cephalus) obtained from Forcados Terminal river in Delta State, Nigeria were analyzed for content in total petroleum hydrocarbons (TPHs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Health risks to human through dietary consumption of seafood were assessed by estimated dietary intake (EDI), estimated weekly intake (EWI) and Target hazard quotient (THQ). Total Aliphatic Hydrocarbon (TAH) showed highest concentration of 0.49 ± 0.29, 0.59 ± 0.94 and 0.97 ± 0.64 mg/kg in hexadecane (I. africana), tetracosane and tetradecane (S. scrombrus). Polycyclic Aromatic Hydrocarbon (PAH) like naphthalene, methylnaphthalene, Acenaphthene and Acenaphthene showed highest mean concentrations of 0.06 ± 0.03, 0.08 ± 0.05, 0.05 ± 0.03 and 0.05 ± 0.04 in I. africana. The result of total petroleum hydrocarbon showed S. scrombrus revealed the highest mean concentration of 3.64 ± 0.94 mg/kg while M. cephalus gave the least Concentration of 0.08 ± 0.01 mg/kg. Heavy metals like Fe, Zn and Cu had their peak concentrations of 46.59 ± 0.34 (S. scrombrus), 10.56 ± 0.18 (C. saira) and 5.95 ± 0.03 mg/kg (S. scrombrus) respectively and it shows a significant difference (p

Optimization of process parameters for the decolorization of Reactive Blue 235 dye by barium alginate immobilized iron nanoparticles synthesized from aluminum industry waste

Abstract: In the present study, we report a comparative study of Reactive Blue 235 (RB235) dye removal using red mud derived biologically synthesized iron nanoparticles (bRMINP) and chemically synthesized iron nanoparticles (cRMINP), both immobilized in barium alginate beads. The parameters like initial RB235 dye concentration, immobilized RMINP concentration, hydrogen peroxide (H 2 O 2 ) concentration and the contact time for RB235 dye removal were optimized based on Box–Behnken design (BBD) by Response Surface Modeling (RSM) at a constant pH and temperature. Under the optimized conditions (concentration of immobilized RMINP = 1500 mg L −1 , contact time = 240 min, and initial concentration of RB235 = 10 mg L −1 ), the RB235 dye removal by the immobilized bRMINP and cRMINP barium alginate beads was 98.75% and 88.88%, respectively. Results show that the removal of RB235 dye increases as increasing the immobilized RMINP concentration and contact time and decreases with increase in the initial concentration of RB235 dye. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy were used to confirm the adsorption of RB235 onto the surface of barium alginate beads.

Hazardous and industrial waste composition and associated management activities in Caspian industrial park, Iran

Abstract: The aim of the present study was to investigate the waste composition and related management practices in Caspian industrial park. In the first step, all the industrial processes, the types and quantities of products, waste generation, management activities and other general data were obtained by means of a structured questionnaire. In the next step, a total number of 20 industries were selected and their wastes were manually sorted and then weighed to determine physical composition of the waste generated. In addition, detailed information about the waste in all industries was identified through interviews and observations. Based on the results, total generation rate of waste in Caspian industrial park was 3890.4 kg/day. Metals, organic waste and paper and cardboard constituted about 80.9% of total waste generated. On the other hand, all other components were responsible for only 19.1% of the waste. It was also indicated that the majority of industrial wastes came from metallic industries (31.2%) and food and beverage industries (26.4%). In addition, total hazardous waste accounted for nearly 6.85% of total waste generated. In order for the best management of industrial wastes, it is very important to increase motivation for waste recycling and reusing among employees and managers.

Health risk associated with some toxic elements in surface water of Ilesha gold mine sites, southwest Nigeria

Abstract: Health risk assessment of toxic elements in water bodies around gold minesites within southwest Nigeria and implication on the miners and residents was carried out in this study. A total of twenty five surface water samples were analysed for some toxic elements such as Pb, As, Cu, Cd, Zn, Co, Fe, Mn, Cr and Ni using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The results showed that Fe, Ba, Mn, Pb, Cr and Ni exceeded the recommended standards deem fit for human consumption in 62.5%, 18.25%, 37.5%, 12.5%, 6.25% and 6.25% of the water samples respectively. Contamination Index showed that 20% of the water samples can be classified as highly contaminated, 24% can be classified as slightly contaminated and only 16% as not contaminated. The hazard quotient values calculated for all toxic elements based on ingestion and dermal exposure to water showed value 1. The health risk index calculated for toxic elements through both ingestion and dermal exposure showed that 16% of the water samples were within unacceptable risk for non-carcinogenic adverse health effect based only on dermal exposure route and Cr, V, Mn, Sb, Fe and As contributed highest to the risk. Cancer risk showed that only Arsenic exceeded acceptable risk for carcinogenic adverse health risk for children and adults and this make Arsenic to be carcinogenic in the water of the study area.

Photo-Fenton-like degradation of Rhodamine B dye from waste water using iron molybdate catalyst under visible light irradiation

Abstract: Iron molybdate Fe 2 (MoO 4 ) 3 nanopowders with different morphologies have been successfully tailored using two different techniques; co-precipitation and sol gel auto-combustion methods Evidently, X-ray diffraction (XRD) profiles manifested that monoclinic Fe 2 (MoO 4 ) 3 with space group P21/a was acquired at different annealing temperatures from 400 to 600 °C for 2 h using both routes. FE-SEM micrographs evidenced that the formed particles was exhibited aggregates of plates staked with different directions for the sample annealed at 400 °C which it was converted to the brain or an array of fused spheres for the samples annealed at 600 °C using co-precipitation strategy. Otherwise, the microstructure of the formed particles was appeared as a homogeneous porous spherical cluster for Fe 2 (MoO 4 ) 3 sample annealed at 400 °C which it was showed a honey comb like for the sample annealed at 600 °C. Overall, Fe 2 (MoO 4 ) 3 nanopowder prepared by co-precipitation method at 400 °C was exhibited the highest photo Fenton catalytic activity with efficiency ∼97% for degradation of RhB dye after 60 min. In this regards, the highest catalytic activity was attributed to the strong absorption of Fe 2 (MoO 4 ) 3 in the visible-light region due to high surface area of the distinct morphologies and generation of reactive OH from H 2 O 2 synergistically activated by both Fe 3+ and MoO 4 2− .

Dicarboxylic cellulose decorated with silver nanoparticles as sustainable antibacterial nanocomposite material

Abstract: Innovative antimicrobial materials are urgently needed to overcome the occurrence antibiotic-resistant bacteria infections. The current research article shows the preparation and characterization of a benign dicarboxylic cellulose/silver nanocomposite with an effective antimicrobial properties. A uniform silver nanoparticles decorated 2, 3 dicarboxylic cellulose having approximately 15 nm size were reported. Dicarboxylic cellulose/silver nanocomposite displayed excellent antibacterial activity against gram positive and gram negative bacteria. According to these results, it is anticipated that cellulose/silver nanocomposites can find interesting applications such as clinical wound healing, biofilms and the coating of biomedical materials.

Treatment of aquaculture wastewater contaminated with metronidazole by advanced oxidation techniques

Abstract: This work analyses the treatment of ornamental aquaculture wastewater contaminated with the antibiotic metronidazole (MTZ) using a reactor with supported TiO 2 . Preliminary photolysis and hydrolysis studies revealed inefficient elimination of this pollutant under the study conditions. The activity of various photocatalysts in suspension in the elimination of 40 mg·L −1 of MTZ was studied, as well as the degradation performance in different aqueous matrices using UV-A radiation. Process efficiency was strongly and negatively affected by the presence of ions in solution, with a 20% decrease in mineralization. The highest reaction rates was observed with the Evonik-P90 (0.0625 min −1 ) versus Hombikat (0.0078 min −1 ). A number of configurations were evaluated to optimise the performance of the reactor with immobilized catalyst in MTZ degradation. Different types of illumination (UV-A and UV-C) were tested as well as the positions of both lamp and catalyst inside the reactor. Various configurations were able to completely eliminate 10 mg·L −1 of MTZ. A greater efficiency was observed in general in the degradation processes with the catalyst immobilized on the outer tube with the internal UV-C lamp (k E.UVC ; 0.042 min −1 ), compared UV-A lamp (k E.UVA ; 0.022 min −1 ). The best configuration was catalyst immobilized on the outer with the internal UV-C lamp and hydrogen peroxide (k E.UVC* ; 0.055 min −1 ).The deposited catalyst was also successfully subjected to continuous re-runs using the optimised configuration with no catalyst deactivation observed. Despite a decrease in photocatalytic activity of 24% after the sixth re-run, 100% MTZ elimination was still achieved. The degradation pathway of metronidazole using TiO 2 photocatalysis has also been proposed and detoxification of the samples after the photocatalytic treatment was evaluated using V. fischeri bacteria test.

Biosynthesis of gold nanoparticles using yellow oyster mushroom Pleurotus cornucopiae var. citrinopileatus

Abstract: In this study, two extracts of Pleurotus cornucopiae var. citrinopileatus mushroom (fresh and dried) were investigated as reducing and capping factors for biosynthesis of gold nanoparticles (AuNPs). In extracellular, AuNPs were synthesized using Chloroauric acid with extracts of mushroom. The incubated solution from gold ions and mushroom’s extract under dark condition were reduced to AuNPs. Fresh mushroom extract showed better reduction. The synthesized AuNPs were characterized using color, UV–visible spectroscopy, FTIR, EDX, FESEM, and HRTEM. Purple color after 24 h of incubation was given indication for AuNPs formation. Results showed that AuNP absorption band was located on a peak of 550 nm for a solution from mixing Au ions with fresh mushroom, and 540 nm for mixing Au ions with the dried one. Both the FESEM and HRTEM confirmed that the formation of AuNPs was mainly spherical within the range of 16–91 nm for AuNPs of dried mushroom and 23–100 nm for AuNPs of fresh one.

Fabrication of smart magnetic nanocomposite asymmetric membrane capsules for the controlled release of nitrate

Abstract: Nitrate contamination of water resources due to excessive use of nitrogen-based fertilizers has become a global health issue. In this work, a recyclable and environmentally sensitive magnetic Fe2O3/PES (Polyethersulfone) nanocomposite asymmetric membrane like capsules (NAMCs) were prepared such that release nitrate in a controlled manner. Different characterization techniques such as SEM, EDAX, DSC, and surface energy measurement were used to systematically characterize the NAMCs. It was observed that the incorporation of only 0.5 wt.% Fe2O3 nanoparticles into NAMC provided a slow and steady release rate of nitrate. A further addition of nanoparticles (from 0.5 wt.% to 1.5 wt.%) into the capsules matrix resulted in an increase in the initial-release rate (IRR, from 3.17 to 4.17 μS/cm min) and maximum release level (MRL, from 36 to 52 μS/cm). The designed capsules also showed recyclability and the ability to respond to the environmental conditions. For instance, IRR increased from 3.17 to 5.31 μS/cm min for NAMCs when temperature increased only by 10 °C. These findings could be considered as a new and green approach to prevent nitrate contamination of water resources in the first place without exacerbating energy issues. Although this work is based on the controlled release of nitrate as the water resources contaminant, the NAMCs can also be used for other nutrients and fertilizers.

Ultra-sensitive p-nitrophenol sensing performances based on various Ag2O conjugated carbon material composites

Abstract: A simple, new, low cost, highly sensitive chemical sensing with various carbon materials of Ag2O–CNT NCs, Ag2O, Ag2O-CB, and Ag2O-GO, which were prepared by simple wet-chemical method in alkaline medium (pH > 10). The Ag2O–CNT NCs were characterized by using many different methods, which are UV/vis. spectroscopy, X- ray diffraction pattern (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy. The Ag2O–CNT NCs were deposited on a flat Glassy carbon electrode (GCE; Surface area: 0.0316 cm2) with binders (nafion 5% ethanolic solution) to fabricate a selective p-Nitrophenol (p-NP) sensor. This chemical sensor was successfully applied to detected p-NP compound with short response time in phosphate buffer phase by using a simple and reliable electrochemical approach (I–V technique). The fabricated Ag2O–CNT NCs chemical sensor exhibited higher sensitivity (103.89 μA μM−1 cm−2) with a very low detection limit (LOD) of 0.091 ± 0.002 nM (signal-to-noise ratio at an SNR of 3) compared to other composites as Ag2O, Ag2O-CB, and Ag2O-GO. The calibration plot is linear (r2 = 0.983) with the linear concentration range (LDR) of 1.0 nM–0.01 mM. Finally, this chemical sensor as many advantages including reliability, reproducibility, higher stability, lower detection limit, ease of integration, and selectivity for toxic p-NP chemicals for the safety of the environment.

Effective removal of mercury from aqueous solution using thiol-functionalized magnetic nanoparticles

Abstract: The present investigation demonstrates the effective removal of Hg(II) ions from aqueous solution by means of thiol-functionalized magnetic nanoparticles (TF-MNPs). After preparation, TF-MNPs have been characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform-infrared spectroscopy (FT-IR), Thermogravimetric (TG) and vibrating sample magnetometer (VSM). The XRD and FESEM analyses revealed the presence of magnetic nanoparticles with an average particle size of 15–30 nm. The result of FT-IR analysis confirmed that the magnetite nanoparticles have been successfully functionalized by thiol groups. The particles illustrated enough response to a magnetic field, hence they could be easily separated from the aqueous solutions. The amount of the grafted functional groups on the surface was assessed using the TG analysis and was observed to be 34.15%. The adsorption capacity was also investigated as a function of both pH in a range of 2–9 and initial concentration. Pseudo-second-order equation as well as both the Langmuir and Freundlich isotherm models could describe the kinetic data and adsorption equilibrium, respectively. The maximum adsorption capacity of the TF-MNPs was found to be 344.82 mg g−1, which is relatively high. The Hg(II) ions were removed effectively from the surface of TF-MNPs utilizing thiourea in HCl solution. The results also indicated that TF-MNPs could provide improved adsorption capacities for removal of Hg(II) from contaminated water, by means of magnetic separation.

Synthesis of nano silver by a marine epibiotic bacterium Bacillus vallismortis and its potent ecofriendly antifouling properties

Abstract: In the present study, biosynthesis of silver nanoparticles (AgNPs) by a newly isolated marine epibiotic bacterium Bacillus vallismortis and its potent antifouling (AF) activity was investigated. Biosynthesized AgNPs were primarily confirmed by change in colour from yellow to brown. UV–vis spectrum of the AgNPs showed surface plasmon resonance (SPR) peak at 426 nm. The AgNPs were further characterized using FT-IR spectroscopy, XRD, SEM and HRTEM analysis. The synthesized AgNPs were narrowly polydispersed and spherical in shape with an average particle size of 23 nm. Antibacterial activity inferred that the AgNPs effectively inhibited marine biofilm forming bacterial strains with minimal MIC and MBC values. Moreover, Confocal Laser Scanning Microscopic images evidenced good antibiofilm efficacy of the AgNPs. It had also strongly inhibited fouling microalgal growth at minimal nanomolar (nM) concentration in the range of 0.5–1 nM. Anticrustacean assay using Artemia franciscana larvae registered LC50 value of 11.59 nM. Further, EC50

Treatment of high organic carbon industrial wastewater using photocatalysis process

Abstract: In Thailand, agricultural machinery manufacturing companies are known to generate high organic carbon wastewater from painting and leak testing processes. Chemical oxygen demand (COD) value in leak test wastewater is found to be in the range of 3000–5000 mg/l. In this study, three scales including lab-scale, pilot-scale and industrial-scale photocatalytic reactors were developed to investigate the efficiency of wastewater treatment. In lab-scale, the 800 ml reactors were set up to optimize the best condition for pH and TiO2 loading. The results suggested that the pH had no effects on the COD removal, whereas the COD removal efficiency was increased by TiO2 loading. The highest COD removal efficiency of 85% was found at the TiO2 loading of 1 g/l. The 200 l reactor of pilot-scale and the 3000 l reactor of industrial-scale were established and continuously operated for 30 days. The results revealed that the COD removal efficiency was >90%, and the COD concentration was reduced to 250–300 mg/l in the treated wastewater. The COD value of treated wastewater met the standard set by the Industrial Estate Authority of Thailand to discharge into a central wastewater treatment plant, which verified the successful implementation of process to the actual industrial wastewater.

The impact of various land uses on the microbial and physicochemical quality of surface water bodies in developing countries: Prioritisation of water resources management areas

Abstract: To protect water resources, the WHO recommends assessing land use influence on water quality, taking into consideration residential development and waste disposal amongst others. Thus, we investigated the impact of unconstructed plots, an informal settlement, an urban residential area, and an industrial area on the microbiological and physicochemical quality of two main tributaries within the Klein Jukskei catchment, Johannesburg, South Africa, to identify areas where immediate resource management strategies were needed. Water samples collected from the tributaries’ sources and upstream and downstream from each land use type (Winter and Spring) were analysed for E. coli (indicator organism), using the Colilert ® 18 system. Physicochemical parameters (Temperature, pH, dissolved oxygen, electrical conductivity, turbidity and total dissolved solids) were measured using multiparameter instruments. The tributaries’ sources had the lowest E. coli counts (Sandspruit – 0.74; North Ridingspruit – 1.18 log 10 MPN/100 mL) during the study. After flowing through the various land uses, mean E. coli counts reached 5.98 (Sandspruit) and 4.85 log 10 MPN/100 mL (North Ridingspruit). E. coli values and all physicochemical parameters (but for pH) downstream from most of the land uses did not meet the South African drinking water quality guidelines. The informal settlement had the most negative impact on the microbial and physicochemical quality of the water within the tributaries. Thus, providing informal settlements with appropriate sanitation facilities is likely to prevent pollution of the water bodies. Protection of the sources should also be implemented while industrial wastes need to be monitored for conformity with water quality guidelines before discharge.

Accurate investigation to determine the best conditions for using NiTiO3 for bromophenol blue degradation in the environment under UV–vis light based on concentration reduction and to compare it with TiO2

Abstract: In this study, bromophenol blue was degraded by NiTiO3 nanoparticles under UV and Visible light irradiation. Due to the toxicity and harmful effects of the bromophenol blue compound in ground and surface water, its photocatalytic decomposition is of utmost importance. NiTiO3 photocatalyst was synthesized by thermal decomposition of titanium tetra butoxide using Ni(NO3)2·6H2O and was used for degradation under UV–vis irradiation. The obtained photocatalyst was characterized by UV–vis spectroscopy, powder X-ray diffraction (XRD), IR spectroscopy, scanning electron microscopy (SEM) and N2 absorption–desorption. BET analysis was performed to calculate the specific surface area, pore diameter, pore volume and percentage of mesopores of NiTiO3. The effects of parameters such as pH, catalyst dosages, and concentrations of bromophenol blue were examined. The results were compared with Degussa P25, a commercial TiO2 powder, which is commonly used in photocatalytic reactions. Additionally, degradation by TiO2 and NiTiO3 under UV and Visible light was tested; NiTiO3 under both UV and visible light showed higher degradation than TiO2 in the same conditions. The results show that NiTiO3 is able to reduce the concentration of bromophenol blue by 91.1% under visible light in an acidic environment.

Coating TiO2 nanoparticles on the surface of transparent plastic granules using combined electrostatic and heating methods for the photocatalytic degradation of organic pollutants in water

Abstract: In this paper, an effective method for superimposing TiO2 nanoparticles on the surface of transparent plastic granules has been reported by combining an electrostatic mechanism and heat treatment. The process was initiated by generating electrostatic charges on plastic granules through the friction mechanism with glass; then, the charged granules were sprinkled with TiO2 nanoparticles. Nanoparticle binding has been improved by heating and softening the granule surface. The coated granules were used to decompose methylene blue (MB) as a wastewater model under solar illumination. The simple theories have been also proposed to explain effect of heating time on coating effectiveness and limitation number of TiO2 particles that can be coated on the granule surface, showing very good agreement between the fitting results and the experimental data.