Showing papers in "Korean Journal of Chemical Engineering in 2019"
TL;DR: In this article, the use of nanomaterials for the removal of different polluting materials from industrial wastewater with a special focus on metal and metal oxide nanommaterials (NMs), carbon-based nanomorphs (CNMs), and nanofiber/nanocomposite membranes.
Abstract: Industrial wastewater is a universal environmental issue. Numerous organic pollutants, heavy metals, and non-disintegrating materials are present at extreme concentrations. Presently, removing these pollutants from industrial wastewater in an effective way has become a momentous issue. Efficient purification procedures are needed to remove those pollutants before disposal. In this direction, wastewater treatment has been one of the nanomaterial applications. Additionally, nanomaterials are innovationally effective for purifying water by using low-budget nanoadsorbents and nanofiltration. This review article highlights the use of nanomaterials for the removal of different polluting materials from industrial wastewater with a special focus on metal and metal oxide nanomaterials (NMs), carbon-based nanomaterials (CNMs) and nanofiber/nanocomposite membranes. The goal is to offer a recent overview and references in the area of emergent nanomaterials used for removing toxic pollutants from real industrial wastewater for researchers and industrializers.
124 citations
TL;DR: In this article, a review presents recent advances in strategies to stabilize heterogeneous catalysts against deactivation for biomass conversion reactions, including leaching, sintering, and poisoning of metals and collapse of catalyst support.
Abstract: Many processes for the conversion of biomass and its derivatives into value-added products (e.g., fuels and chemicals) use heterogeneous catalysts. However, the catalysts often suffer from deactivation under harsh reaction conditions, such as liquid phase at high temperatures and pressures. The catalyst deactivation is a big obstacle to developing industrially relevant biomass conversion processes, including leaching, sintering, and poisoning of metals and collapse of catalyst support. Different approaches have been applied to limit the reversible and irreversible deactivation, highly associated with the kind of catalyst, reactants, reaction conditions, etc. This review presents recent advances in strategies to stabilize heterogeneous catalysts against deactivation for biomass conversion reactions.
97 citations
TL;DR: In this paper, the results reveal that, natural zeolite is an excellent and affordable adsorbent for removal of crystal violet from wastewater as compared to activated carbon, and that it possesses a higher adsorption capacity than activated carbon.
Abstract: Natural zeolite as a low cost clay was tested for removal of crystal violet known as a noxious dye. Five characterization techniques were used for this study Optimizing and modeling of adsorption were performed at minimum time by an applicable technique named as response surface methodology (RSM). Three effective variables (pH, temperature (T) and adsorbate-to-adsorbent ratio (a/A)) were monitored to obtain the dye removal efficiencies. The maximum removal of dye was obtained at pH=10, T=25°C and a/A=0.1 g/g. For natural zeolite, the Fractal-Langmuir model was selected as an appropriate model for kinetic studies and the Freundlich isotherm was the best isotherm for equilibrium studies. Thermodynamic investigations showed that the adsorption of dye on natural zeolite is endothermic process and a spontaneous reaction. The maximum dye adsorption capacity of natural zeolite and Merck activated carbon on the surface of each adsorbent was obtained at 177.75 and 84.11 mg/g, respectively. In comparison with the maximum adsorption capacity of activated carbon obtained from Merck Company, we can conclude that natural zeolite possesses a higher adsorption capacity. These results reveal that, natural zeolite is an excellent and affordable adsorbent for removal of crystal violet from wastewater as compared to activated carbon.
54 citations
TL;DR: In this article, an efficient activated carbon (PAAC) was synthesized from the Populus alba tree, and fluoride ions were removed from samples of synthetic and real wastewaters.
Abstract: Efficient activated carbon was ultrasonically synthesized from the Populus alba tree, and fluoride ions were removed from samples of synthetic and real wastewaters. The effects of various parameters including pH (2–10), time (5–180 min), contaminant concentration (10–100 mg/L), sorbent dose (1–7 g/L), and co-existing ions on the fluoride removal using Populus alba activated carbon (PAAC) were revealed. The physico-chemical characteristics of PAAC were determined using SEM, FTIR, BET, XRD, and EDX mapping. The specific surface area and pore volume of the mesoporous PAAC were obtained as 707.39m2/g and 0.40 m3/g. The study found that the maximum removal efficiency of fluoride (93.37%) occurred under the fluoride concentration of 10 mg/L, PAAC of 4 g/L, pH of 6, and contact time of 100 min. The isotherms and kinetics data could be suitably reflected by the Freundlich and the pseudo-second-order kinetic models, respectively. Langmuir maximum monolayer adsorption capacity of the ultrasonic-assisted PAAC was measured as 77.12mg/g. Sorption of fluoride ions onto PAAC is feasible and an exothermic process. According to the field test, PAAC can significantly remove fluoride and other pollutants like BOD5, COD, Ni, Co, and Pb from glass and shipyard wastewater samples.
44 citations
TL;DR: In this article, a simplified strategy for facilely fabricating antifouling graphite carbon nitride/silver phosphate (g-C3N4/Ag3PO4) nanocomposite photocatalytic polyvinylidene fluoride (PVDF) porous membranes was developed for effective removal of rhodamine B (RhB).
Abstract: A simplified strategy for facilely fabricating antifouling graphite carbon nitride/silver phosphate (g-C3N4/Ag3PO4) nanocomposite photocatalytic polyvinylidene fluoride (PVDF) porous membranes was developed for effective removal of rhodamine B (RhB). g-C3N4/Ag3PO4 heterojunction was strongly fixed to the interior of the PVDF membranes via phase inversion method. The membrane structure was analyzed by Fourier transform spectrophotometer (FT-IR). The morphology of the prepared membranes was investigated using scanning electron microscopy (SEM), EDX-mapping and atomic force microscopy (AFM), respectively. All prepared nanocomposite photocatalytic PVDF membranes exhibited a typically porous structure, and g-C3N4/Ag3PO4 nanocomposites were well dispersed inside the membranes. The obtained g-C3N4/Ag3PO4 heterojunction nanoparticle decorated PVDF membrane had a lower water contact angle of 79° and higher porosity of 85% than that of other two control membranes. The nanocomposite photocatalytic PVDF porous membranes had extremely high permeation flux over 1,083 L·m-2·h-1, and could be used for the removal of RhB. The removal efficiency of g-C3N4/Ag3PO4-PVDF membranes towards RhB solution under visible light irradiation reached 97%, higher than that of the pure PVDF membranes (41%) and g-C3N4-PVDF membranes (85%). Remarkably, the flux performance and flux recovery ratio (FRR) of membranes revealed that the g-C3N4/Ag3PO4-PVDF membranes could recover high flux after fouling, which presented better fouling resistance. Furthermore, the fabricated antifouling g-C3N4/Ag3PO4 nanocomposite photocatalytic PVDF porous membranes exhibited excellent recyclability. Therefore, it is expected that g-C3N4/Ag3PO4-PVDF membranes could provide an energy-saving strategy for effective removal of organic dyes wastewater and have a great potential for practical wastewater treatment in the future.
42 citations
TL;DR: In this article, a review of various types of heterogeneous activators for the activation of persulfate and its proposed oxidation mechanisms is presented, which concentrates closely on various types and types of catalysts.
Abstract: Activated persulfate has gained substantial interest owing to its potential removal efficiency toward recalcitrant organic pollutants, including pharmaceuticals, pesticide products, and industrial dyes. Various investigations into the activation of persulfate have been conducted to achieve a higher oxidation efficiency. Specifically, heterogeneous catalysts have been extensively applied to the activation of persulfate, enabling a more simplistic and practical method compared to other approaches. Therefore, the present review concentrates closely on various types of heterogeneous activators for the activation of persulfate and its proposed oxidation mechanisms.
40 citations
TL;DR: In this article, the porosity-induced carbon nanofibers (CNFs) were used to achieve high-performance supercapacitor electrode, achieving an energy density of 9.9 Wh/kg, power density of 0.69 kW/kg and capacitance retention of 89% after 5000 charge discharging cycles.
Abstract: Carbon nanofiber is a well-known carbon nanostructure employed in flexible supercapacitor electrode. Despite recent developments, improvement in the performance of carbon nanofiber-based electrode is still the subject of intense research. We investigated the supercapacitor performance of porosity-induced carbon nanofibers (CNFs). The fabrication process involves electrospinning, calcination, and subsequent etching. The porous CNF not only delivers a higher capacitance of 248 F/g at a current density of 1 A/g, but also exhibits a higher rate performance of 73.54%, lower charge transfer resistance and only 1.1% capacitance loss after 2000 charge-discharge cycles, compared to pristine CNF. The excellent electrochemical behavior of porous CNF is correlated with the degree of graphitization, a higher volume of mesopores, and enhanced surface area. The as-fabricated symmetric device comprising porous CNF exhibits an energy density of 9.9 Wh/kg, the power density of 0.69 kW/kg and capacitance retention of 89% after 5000 charge-discharge cycles. The introduction of porosity in CNFs is a promising strategy to achieve high-performance supercapacitor electrode.
40 citations
TL;DR: In this article, the authors examined unsteady double-strained EMHD mixed convection flow of nanofluid via permeable stretching sheet and looked at the convective heat and mass boundary conditions as well as the Navier velocity slip.
Abstract: This study numerically examined unsteady double stratified EMHD mixed convection flow of nanofluid via permeable stretching sheet. It also looked at the convective heat and mass boundary conditions as well as the Navier velocity slip. In the thermal field, the effects of radiative heat transfer, heat generation/absorption, viscous dissipation, together with Ohmic heating (both magnetic and electric fields) were considered. The concentration field accounts for the chemical reaction. These show the physical behavior of electromagnetohydrodynamic flow associated with the problem formulation. The characteristics in regard to convective heat and mass, Navier slips conditions, as well as double stratification, were imposed. Such structure arises in energy efficiency and performance, which is achievable without higher pumping power, serves in the extrusion manufacturing process involving the thermal system for efficient devices particularly in polymeric, paper production, and food processing. The governing equations, which are nonlinear partial differential equations, were modelled by ordinary differential equations using suitable transformations. The ODEs were solved numerically, using implicit finite difference method (Keller box method). The physical implications deliberated on the behavior via the velocity, thermal energy, and concentration fields as well as the skin friction coefficient; the Nusselt and Sherwood numbers were scrutinized in relation to several parameters via mathematical model. The analysis shows that thermal and concentration stratifications decrease the distributions adjacent to the sheet surface, indicating decrease in the concentration nanoparticles and reduction in thermal energy. Augmentation occurs with convective heat and mass Biot numbers with the fields. The electric and magnetic parameters exhibit opposite flow behavior to the velocity and temperature. Chemical reaction and viscous dissipation weaken the concentration profile. Numerical results were compared with the published data available in the literature for limiting cases, and good agreement was noticed.
35 citations
TL;DR: In this article, the authors studied the synthesis, characterization clarification, and dye adsorption ability of chromium-based metal-organic framework (MIL-101(Cr)) with ultrasound-assisted green synthesized in a DMF-free way.
Abstract: We studied the synthesis, characterization clarification, and dye adsorption ability of chromium-based metal-organic framework (Materials Institute Lavoisier: MIL-101(Cr)). MIL-101(Cr) with 1 : 1 molar ratio of metal to ligand was ultrasound-assisted green synthesized in a DMF-free way and its adsorption capacity for pollutant remediation was studied. Several analyses were applied to clarify the characterization of materials, including TGA, SEM, XRD, FTIR, BET, and Zeta potential. Direct Red 80 (DR80) and Acid Blue 92 (AB92) were used to make model dye bearing wastewater. Response surface methodology (RSM) historical modeling was applied to the data to achieve an accurate model of the experiment. Adsorption kinetics and isotherms models were fully studied. The powerful adsorbent was the MIL- 101(Cr) with the M/L=1 : 1, which represented the high specific surface area (SSA) of 2,420 m2/g and surface charge of +27.2 mV. The maximum adsorption capacity was obtained 227 mg/g for DR80 and 185 mg/g for AB92. With an eye to the real-world application, the synthesized adsorbent well operated by removing dyes from the wastewater and high reusability after four cycles.
34 citations
TL;DR: In this article, the effect of operating temperature on the performance of aqueous redox flow battery (ARFB) was investigated based on electrochemical characterization, although ferrocyanide is in a quasi-reversible state at room temperature, the state becomes irreversible as temperature increases.
Abstract: Carboxylic acid functionalized alloxazine (alloxazine-COOH) and ferrocyanide are utilized as active species for aqueous redox flow battery (ARFB), and the effect of operating temperature on the performance of ARFB was investigated. Based on electrochemical characterization, although ferrocyanide is in a quasi-reversible state at room temperature, the state becomes irreversible as temperature increases. By the use of carbon felt (CF) containing carbon-oxygen functional groups, the activity of ferrocyanide is enhanced without side effect, such as irreversible redox reactivity. This is because the hydrophilic (charge-dipole) interaction between dipole groups (hydroxyl and carbonyl groups) onto CF and ferricyanide ions promotes the oxidation reaction of ferricyanide. Though alloxazine-COOH coated on glassy carbon electrode shows irreversible state compared to ferrocyanide as temperature increases, the activity of alloxazine-COOH is also enhanced by using the hydrophilic group doped CF. To prove whether the redox reactivity of the two active species is improved with increase in temperature, the performance of ARFBs using them was evaluated in the different temperature conditions. When the temperature of both anolyte and catholyte is 45 °C, average discharge capacity and state of charge are 24 Ahr·L−1 and 90%, and the values are reduced to 23 Ahr·L−1 and 86% in ARFB of only catholyte heating, 22 Ahr·L−1 and 82% in ARFB of only anolyte heating and 21.3 Ahr·L−1 and 80% with no heating. Based on that, it is speculated that the operation temperature can be a factor in determining the performance of ARFB.
34 citations
TL;DR: In this article, the role of membrane technology in acid mine water treatment is discussed together with the factors that determine membrane performance for acid mine drainage effluents, and some solutions to the challenges are presented.
Abstract: The activities of mining industries are attracting more scrutiny as the concern of limitations of conventional technology for wastewater treatment and the potential use of wastewater have resulted in accelerated attention in membrane technologies. The paucity of water and industrial environmental guidelines has resulted in the application of membrane technologies in wastewater treatment, especially in the mining industry. Although many conventional physical and chemical processes have been employed to treat acid mine drainage (AMD), they have, however, demonstrated low efficiency and high cost. Membrane technologies have proven to be an important part in the treatment of AMD in order to reduce water paucity. Apart from addressing water paucity, membrane technologies meet high-level application with respect to ease of use, adaptability and environmental impacts. This paper reviews the use of membrane in the published literature for the treatment of acid mine waters and, for the recovery of valuable metals from acid mine drainage effluents. The role of membrane technology in acid mine water treatment is discussed together with the factors that determine membrane performance for AMD treatment. The challenges of membrane technology in acid mine water treatment were reviewed and some solutions to the challenges are presented.
TL;DR: In this article, the authors investigated the application of lab-scale sequencing batch (SBR) and sequencing batch biofilm reactors (SBBR) for treatment of dairy wastewater under organic loading of 1,130-1,560 gBOD5/m3·d.
Abstract: Application of lab-scale sequencing batch (SBR) and sequencing batch biofilm reactors (SBBR) for treatment of dairy wastewater was investigated under organic loading of 1,130-1,560 gBOD5/m3·d. The main characteristics of the dairy wastewater were: pH=4.9, chemical oxygen demand (COD)=16,264 mg/l; biological oxygen demand (BOD5)=10,536 mg/l, PO4-P=342 mg/l; total nitrogen (TN)=224 mg/l. SBBR was filled with the Kaldnes K1 biocarrier at 30% of the volume of empty reactor. The SBR and SBBR were operated in fixed 24 h cycles, each consisting of 30 min fill up, 22 h aeration, 1.5 h settle, 30 min decant, and idle with a hydraulic retention time (HRT) of 8 days. Operational parameters such as pH, dissolved oxygen (DO), mixed liquor suspended solid (MLSS), solids retention time (SRT) and sludge volume index (SVI) were monitored during the whole cycle. The effects of these parameters on the COD, nitrogen and phosphorus removal were discussed in this paper. As a result, adding biocarrier to the reactor had a positive effect on organic with COD removal of 63.5% for SBR and 81.8% for SBBR and nutrient removal with ammonium removal of 66.0% for SBR and 85.1% for SBBR in treatment of dairy wastewater.
TL;DR: In this article, Nanoporous activated garlic stem carbon (AGSC) was prepared from garlic stem waste and used to remove As(III) from synthetic water under complete batch experiments.
Abstract: Nanoporous activated garlic stem carbon (AGSC) was prepared from garlic stem waste and used to remove As(III)from synthetic water under complete batch experiments. Characterization studies of AGSC were performed by FTIR, SEM, EDX, BET, XPS and XRD techniques. Batch adsorption experiments were carried out to study the adsorption of As(III) onto AGSC. Maximum removal of 93.3% of As(III) was obtained at optimum condition of pH 6, the adsorbent dose 5 g/L, equilibrium time 150 min, initial As(III) concentration 400 µg/L and temperature 298 K. Both Langmuir and Temkin isotherm model fitted well to the experimental data as compared to Freundlich isotherm. Kinetics indicated that the adsorption of As(III) was more suitable for pseudo-second-order than pseudo-first-order and Elovich model. The mass transfer mechanism could be described by Weber-Morris and Boyd mass transfer model. The maximum adsorption capacity of AGSC for As(III) removal was found to be 192.30 µg/g. The negative enthalpy and free energy change indicated that the adsorption process of As(III) onto AGSC was exothermic and spontaneous. The negative value of entropy change suggested decreasing randomness at the AGSC-aqueous As(III) interface during As(III) adsorption.
TL;DR: In this paper, the NiNPs-doped carbon beads were synthesized and applied as a substrate to grow CNFs by chemical vapor deposition, and the Ni-CNF-RhB colorimetric probe exhibited fast response and selective determination towards Cr3+ and Pb2+ over the 0.1-10 ppm concentration range of their respective solution pH.
Abstract: Nickel nanoparticle (NiNPs)-doped carbon nanofiber (CNF) grafted with Rhodamine-B (RhB) dye (Ni-CNF-RhB), was prepared and utilized as a colorimetric probe for detection and measurements of chromium (Cr3+) and lead (Pb2+) metal ions in aqueous systems. An intense pink solution was obtained within 30 s on the exposure of the colorless Ni-CNF-RhB probe to the metal ions (Cr3+ and Pb2+) solution. Briefly, the NiNPs-doped carbon beads were synthesized and applied as a substrate to grow CNFs by chemical vapor deposition. The Ni-CNF-RhB colorimetric probe exhibited fast response and selective determination towards Cr3+ and Pb2+ over the 0.1-10 ppm concentration range of their respective solution pH. The developed probe also showed the pH-dependent colorimetric response, thereby, selectivity determination of the metal ions. The detection limits of the colorimetric probe against Cr3+ and Pb2+ are 203 and 132 nM, respectively. The binding ability of the RhB-dye was augmented by CNF and NiNPs, while the carbon beads provided support to CNF to help probe in detection application and its re-usability. The method to prepare the colorimetric probe is simple, novel, selective, and the probe can be efficiently used for the fast detection (naked eye) and measurements of toxic metal ions in aqueous systems.
TL;DR: In this paper, a new bi-functional aminosilane crosslinker (3-aminopropyl(diethoxy)methylsilane (APDEMS)) was applied to improve the gas separation performance of a highly permeable but low selective Pebax 2533 membrane.
Abstract: Commercial poly (ether-block-amide) (Pebax®) copolymers are thermoplastic elastomers that have attracted attention as membrane materials due to their high performance in CO2 separation. In this study, a cross-linking reaction is reported as a viable strategy to improve the gas separation performance of a highly permeable but low selective Pebax 2533 membrane. To this end, a new bi-functional aminosilane cross-linker (3-aminopropyl(diethoxy)methylsilane (APDEMS)) was applied. Cross-linked Pebax 2533 membranes were prepared via solution-casting with different amounts of APDEMS ranging from 0.5 to 4 wt%, to investigate the effect of the aminosilane concentration on the membrane performance. Gas separation with prepared membranes was studied for CO2/N2 at the feed pressure ranges of 2-10 bar. Instrumental analyses were applied to investigate the effect of the cross-linking reaction on the structure and properties of the membranes. The results showed that a 2 wt% APDEMS cross-linked Pebax 2533 membrane has the best gas separation performance. The CO2/N2 ideal selectivity of the cross-linked Pebax 2533 increased twice compared to the neat Pebax 2533 membrane at the feed pressure of 2 bar, while the CO2 permeability experienced a slight decrease by cross-linking, but still remains higher than the permeability of other Pebax grades.
TL;DR: In this article, a ternary layered double hydroxide, MgCoAl (MCA), and its graphene-based composite (G/MCA) were fabricated via a simple co-precipitation technique.
Abstract: Ternary layered double hydroxide, MgCoAl (MCA) and its graphene-based composite (G/MCA) were fabricated via a simple co-precipitation technique. The composites along with their calcined products (MCA-C) and (G/MCA-C) were used as adsorbents for the removal of an anionic dye, methyl orange (MO), from aqueous phase. The characterization results (scanning electron microscopy and transmission electron microscopy) revealed homogeneous dispersion of graphene onto the MCA. Calcination of G/MCA resulted in a rough and heterogeneous surface with significant improvement in oxygen functionalities and surface area, which plays a crucial role in improved dye adsorption performance. Adsorptive equilibrium was established at 240 min for MCA and G/MCA and 180 min for MCA-C and G/MCA-C respectively at pH 3 and optimum dosage of 10 mg. The Redlich-Peterson and Langmuir isotherm models closely describe the adsorption process with maximum adsorption capacities of 357.14, 384.62, 400.12 and 434.78 mg/g for MCA, G/MCA, MCA-C, and G/MCA-C respectively. Kinetics modeling indicates the adequacy and fitness of the pseudo-second-order model. A thermodynamics evaluation substantiates the exothermic nature of the adsorption processes. The MO-graphene ternary LDH composite adsorption process is controlled by several mechanisms including hydrogen bonding, surface adsorption, chemical and electrostatic interactions with surface reconstruction. The high removal efficiency of the MO coupled with high recovery and reusability of these nanomaterials showcases their potential for deployment in wastewater treatment.
TL;DR: In this paper, a new type of polyether-imide (PEI)-based nanofiltration membranes was prepared by introducing octaglycidyloxypropyl-silsesquioxane (GlyCidyl POSS) into PEI matrix for heavy metals ions removal from water.
Abstract: A new type of polyether-imide (PEI)-based nanofiltration membranes was prepared by introducing octaglycidyloxypropyl-silsesquioxane (Glycidyl POSS) into PEI matrix for heavy metals ions removal from water. The separation performance of fabricated membranes in Na2SO4, Pb(NO3)2, Ni(NO3)2 and Cu(NO3)2 removal from water as well as their flux and antifouling property was evaluated. Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) analytical method, atomic force microscope (AFM), porosity contact angle, and water content were also used in membrane characterization. The results indicated higher hydrophilicity, pure water flux (PWF) and salt rejection for PEI-POSS membranes compared to neat PEI ones. The morphological images showed good tuning porosity, finger- and spongy-like structure. The highest porosity observed for [PEI-1 wt% glycidyl POSS] with the best antifouling property. The surface roughness also decreased by incorporating of POSS into PEI matrix. The pure water flux increased from 14.3 (L/m2h) for neat PEI membrane to 36 (L/m2h) for [PEI-0.1 wt% glycidyl POSS]. Moreover, Na2SO4, Pb(NO3)2, Cu(NO3)2 and Ni(NO3)2 rejection measured 78%, 94%, 99%, 42% for [PEI-1 wt% glycidyl POSS] membrane, whereas they were 69%, 44%, 40% and 16% for the virgin PEI membrane, respectively. Results showed a good potential for [PEI-POSS] membrane in Cu and Pb ions removal beside its high PWF and antifouling ability.
TL;DR: The potential bio-applications of bioMOFs in several fields such as biomedicine, biosensing and bioimaging, antimicrobial applications, biomimetic catalysis, chiral separation, and environmental protection are demonstrated.
Abstract: Biological metal-organic frameworks (bioMOFs) are a new subclass of the MOF family. In comparison with traditional MOFs, the bioMOFs are made of multifunctional biologically related ligands (bio-ligand) and metal ions. The bio-ligands confer biological compatibility for traditional MOFs, thus providing many opportunities for a wide array of biological applications. This review highlights the recent advances in the synthesis of bioMOFs comprising multifunctional bio-ligands and metal ions. These bio-ligands include nucleobases, amino acids, peptides, proteins, cyclodextrin, saccharides, and other biomolecules. Furthermore, the potential bio-applications of bioMOFs in several fields such as biomedicine, biosensing and bioimaging, antimicrobial applications, biomimetic catalysis, chiral separation, and environmental protection are also demonstrated.
TL;DR: In this paper, the performance of catalysts for anodic biocatalysts for the enzymatic biofuel cell (EBC) was investigated, and it was shown that the catalytic activity for glucose oxidation reaction (GOR) representing the electron transfer rate between GOx and glucose fuel is mostly enhanced in CNT/PEI/NQ/GOx, while other quinones have problems about attracting electrons (AQ and 15DHAQ).
Abstract: Glucose oxidase (GOx) and four different quinone derivatives (p-benzoquinone (BQ), naphthoquinone (NQ), anthraquinone (AQ) and 1,5-Dihydroxyanthraquinone (15DHAQ)) based biocomposites were embedded in polyethyleneimine (PEI) and then immobilized on carbon nanotube (CNT) substrate (CNT/PEI/Quinone/GOx). These catalysts were then used as the anodic biocatalysts for the enzymatic biofuel cell (EBC). According to the performance investigations of catalysts, the catalytic activity for glucose oxidation reaction (GOR) representing the electron transfer rate between GOx and glucose fuel is mostly enhanced in CNT/PEI/NQ/GOx. It is because two benzene rings of NQ play a role in attracting and releasing electrons effectively, increasing the catalytic activity for GOR, while other quinones have problems about attracting electrons (AQ and 15DHAQ) and wrong position of the reactive site for electron transfer (BQ). Excellent electron transfer rate constant (1.1 s-1) and Michaelis-Menten constant (0.99mM) are outstanding evidence for that. Furthermore, when the catalyst is utilized for EBC, high power density (57.4 μWcm-2) and high open circuit voltage (0.64 V) are accomplished.
TL;DR: In this article, the authors evaluated the efficacy of photo-oxidation (P) and electrooxidation processes in the removal of amoxicillin (AMX) from wastewater, either as integrated or separate processes.
Abstract: The recent increase in the global consumption of antibiotics has led to faster entry of these pollutants into the environment as well as an increase in public concern about its impact on ecosystem and human health. Generally, due to high toxicity of antibiotics, biological methods are not used to treat these pollutants; therefore, advanced oxidation processes are recommended to treat and reduce the toxicity of the wastewater. In this study, we evaluated the efficacy of photo-oxidation (P) and electro-oxidation (E) processes in the removal of amoxicillin (AMX) from wastewater, either as integrated or separate processes. Moreover, the effect of variables, including current density (2-100 mA/cm2), reaction time (2–120 min), and electrolyte concentration (100–1,000 mg/l) on antibiotic removal efficiency were investigated by Box Behnken design under response surface methodology, and optimal conditions were determined for pollutant removal. Then, the effect of AMX concentration and pH variables on the removal efficiency was investigated. The COD removal efficiency was also evaluated under optimal conditions, and eventually the toxicity and bioavailability of the effluent from the combined Photo-Electro oxidation process (PE) were examined. The optimal conditions for variables, including current density, reaction time, and electrolyte concentration for removal efficiency of 62.4%, were 94 mA/cm2, 95 min and 997 mg/l, respectively. Investigating the Amoxicillin and pH variables showed that by reducing the contaminant concentration and pH, the antibiotic removal efficiency increased. The toxicity and bioavailability of the final effluent show the reduction of both parameters in the PE reactor effluent. The PE process can provide an appropriate function to reduce the toxicity and antibacterial properties of effluent by removing more than 60% of amoxicillin and 30% of COD from wastewater.
TL;DR: In this paper, a single-step potassium hydroxide synthesized activated carbon was prepared from Schima wallichii biomass by optimizing process parameters at different carbonization temperature and biomass to KOH impregnation ratio.
Abstract: Single-step potassium hydroxide synthesized activated carbon was prepared from Schima wallichii biomass by optimizing process parameters at different carbonization temperature (500 °C, 600 °C, 700 °C and 800 °C) and biomass to KOH impregnation ratio (1: 0, 1: 1, 1: 2 and 1: 3). The optimum condition for obtaining the best activation carbon was found to be at 600 °C and 1: 2 impregnation ratio with BET surface area, total pore volume, and pHzpc of 1,005.71m2g−1, 0.491 cm3g−1 and 6.11, respectively. SEM and XRD analysis revealed the ordering of the graphitic layer with more pores in the carbon matrix at optimized conditions. Batch adsorption experiments were run for fluoride adsorption and fitted, of which Langmuir isotherm model seems to be the best-fitted model with maximum adsorption capacity of 2.524mgg−1. Adsorption kinetics was elucidated best with the pseudo-second-order kinetic model. Theoretical calculations indicate that the adsorption of fluoride is favorable on edge site of both zig-zag and arm chair carbon models with chemisorption type of interaction. Fluoride uptake was found to be affected by the presence of co-ion in the order: $$\rm{CO_3^{2-}} >SO_4^{3-} >NO_3^{-} >Cl^-$$
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TL;DR: In this article, the efficiency of oxide based hierarchical heterostructure as adsorbent for the treatment of organic dyes, Methyl orange (MO) and Methylene Blue (MB), containing solution was investigated.
Abstract: We investigated the efficiency of oxide based hierarchical heterostructure as adsorbent for the treatment of organic dyes, Methyl orange (MO) and Methylene Blue (MB), containing solution. Nanocrystals such as ZnO nanorods (at various temperatures of 30, 60 and 75 °C) and SnO2 nanoparticles were synthesized by electrodeposition method and hydrothermal approaches, respectively. SnO2-ZnO heterostructures were formed by spin coating SnO2 nanoparticles on ZnO nanorods matrix to form a heterostructured film. The surface morphologies and structural characterization of as-prepared heterostructures were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. While, absorption spectra of all samples were examined by UV-vis diffuse reflectance spectroscopy. The photocatalytic activities of as-prepared samples for organic dyes degradation were tested under UV light as model reaction. The SnO2-ZnO heterostructured photocatalyst showed superior activities than individual ZnO and SnO2 nanocrystals. This heightened behavior was attributed to its better charge separation capability and the slow charge recombination originating due to difference in energy values of conduction band edges of SnO2 and ZnO. The SnO2-ZnO heterostructure demonstrated better stability and recyclability up to five times, which is highly desirable for potential industrial applications including dye degradation and wastewater treatment systems.
TL;DR: In this paper, the removal efficiency of humic acid from aqueous solutions by cotton coated with graphene oxide has been investigated as batch on an experimental scale, where a self-arrangement approach was introduced in fabrication of the cotton adsorbent.
Abstract: We investigated the removal efficiency of humic acid from aqueous solutions by cotton coated with graphene oxide. This research has been conducted as batch on an experimental scale. A self-arrangement approach was introduced in fabrication of the cotton adsorbent coated with graphene oxide. To determine the effect of parameters, including initial concentration, pH, adsorbent dosage and contact time, central composite design (CCD) was employed in response surface method (RSM). The adsorption kinetics were determined based on different times of adsorption of humic acid. Further, the adsorption isotherms were also examined using different concentrations of humic acid. The results obtained showed that with increasing adsorbent dosage and contact time, the removal efficiency increased, while with increasing pH and initial concentration of humic acid, the removal efficiency decreased. The optimal values based on RSM method were obtained as the following: humic acid initial concentration=13.61 mg/L, pH=3.87, adsorbent dosage=0.61 g, and contact time=168.43 min. Langmuir isotherm with R2=0.9987 has been the most suitable model for explaining the adsorption process. Investigation of the adsorption kinetics indicated that humic acid adsorption follows pseudo-second-order model (R2=0.9822). The results indicated that the cotton adsorbent coated with graphene oxide has a good potential for removal of humic acid from aqueous solutions. Mechanical flexibility, availability, and low operational energy costs are among the advantages of this method for fabrication of this adsorbent, which can be developed and used for reducing environmental contaminants.
TL;DR: In this paper, super-hydrophobic and super-oleophilic Ni foam was fabricated by immersion coating and drying method by using a mixture of polytetratluoroethylene (PTFE) and hydrophobic fumed silica (R805).
Abstract: Superhydrophobic and superoleophilic Ni foam was fabricated by immersion coating and drying method. The Ni foam was immersed in a mixture containing polytetratluoroethylene (PTFE) and hydrophobic fumed silica (R805). The mixture was dispersed in a poly(vinylidene fluoride) (PVDF) solution and the PVDF was used as a binder. The as-prepared Ni foam showed superhydrophobic and superoleophilic properties simultaneously and had a water contact angle (WCA) of 155° for water and an oil contact angle (OCA) of 0° for oil. The PTFE-coated Ni foam maintained high separation efficiency after repeated separations (40 times) above 96% for the more viscous olive oil/water mixture and above 99% for the hexane/water mixture. The as-prepared nickel foam proved to be an excellent candidate for the separation of oil and water mixtures.
TL;DR: In this article, the authors revisited various milestone studies regarding the core/shell heterostructures of colloidal quantum dots from the viewpoint of electroluminescence materials.
Abstract: The exceptional quality of light generated from colloidal quantum dots has attracted continued interest from the display and lighting industry, leading to the development of commercial quantum dot displays based on the photoluminescence down-conversion process. Beyond this technical level, quantum dots are being introduced as emissive materials in electroluminescence devices (or quantum dot-based light-emitting diodes), which boast high internal quantum efficiency of up to 100%, energy efficiency, thinness, and flexibility. In this review, we revisit various milestone studies regarding the core/shell heterostructures of colloidal quantum dots from the viewpoint of electroluminescence materials. Development of nanostructured colloidal quantum dots advanced from core/shell heterostructure, core/thick shell formulation, and delicate control of confinement potential shape has demonstrated close correlation of the photophysical properties of quantum dots with the performance of electroluminescence device, which provided useful guidelines on the heterostructured quantum dots for mitigating or eliminating efficiency limiting phenomena in quantum dot light emitting diodes. To enable practical and high performance quantum dot-based electroluminescence devices in the future, integration of design concepts on the heterostructures with environmentally benign systems will be crucial.
TL;DR: ZnO nanorods were prepared through a sol-gel process by adding various amounts of water at low temperature and atmospheric pressure conditions for application as a photocatalyst as discussed by the authors, which can overcome fast recombination of photogenerated electrons and holes that inhibits photocatalytic efficiency.
Abstract: ZnO nanorods were prepared through a sol-gel process by adding various amounts of water at low temperature and atmospheric pressure conditions for application as a photocatalyst. The 1-D ZnO nanostructures can overcome fast recombination of photogenerated electrons and holes that inhibits photocatalytic efficiency. X-ray diffractometer and transmission electron microscopy measurements confirmed that the (002)/(100) intensity ratio increased from 0.83 to 1.34 and the morphology of the ZnO nanoparticles was changed from a spherical shape to nanorods with the addition of water. UV-vis spectroscopy showed a red shift from 360 nm to 371 nm, which indicates a decrease of the band gap energy. PL measurements of the ZnO nanorods showed a 103 times improvement of the NBE/DLE intensity ratio compared to the ZnO nanospheres. When the photocatalytic efficiency of the ZnO nanoparticles was estimated for the degradation of methylene blue dye under irradiation of UV light, the photocatalytic kinetic constant increased from 0.067 min−1 to 0.481 min−1. As a result, longer ZnO nanorods showed better photocatalytic performance.
TL;DR: In this article, different sizes of amino-modified silica nanoparticles (SiNPs) were synthesized with 10-40nm in diameter (AMS-10 to 40), and their properties were characterized in terms of size and surface modification using transmission electron microscope (TEM), dynamic light scattering (DLS), zeta potential, elemental analyses (C, H, N), thermal gravimetric analysis (TGA) and Fourier transform infra-red (FTIR).
Abstract: Phenols constitute a widespread class of water pollutants that are generated from many industries and are known to cause a significant threat to the aquatic environment. Phenols are, therefore, considered as dangerous pollutants by global international quality organizations. This has led to a growing demand for an efficient technology for phenol removal from wastewater. Different sizes of amino-modified silica nanoparticles (SiNPs) were synthesized with 10–40nm in diameter (AMS-10 to 40), and their properties were characterized in terms of size and surface modification using transmission electron microscope (TEM), dynamic light scattering (DLS), zeta potential, elemental analyses (C, H, N), thermal gravimetric analysis (TGA) and Fourier transform infra-red (FTIR). The adsorption process was carried out utilizing batch mode experiment; the influence of various factors including pH of the medium, the contact time, the initial concentration of the adsorbate and the dose of the adsorbent on the phenol adsorption efficiency of SiNPs of various sizes were investigated. Phenol removal efficiency was found to be size-dependent, such that the phenol adsorption capacity of the SiNPs was in the following order: AMS-10>AMS-20>AMS-30>AMS-40 nm. The adsorption capacity and binding coefficient were calculated to be 35.2mg/g and 0.192mg/L, respectively, for AMS-10. The amino-modified SiNPs were found to be promising adsorbents for the phenol ions removal from the aqueous medium.
TL;DR: In this article, the absorption kinetics of carbon dioxide (CO2) released from power plant exhaust using activated mixture of 2-amino-2-methyl-1-propanol (AMP) upgraded by piperazine (PZ) were investigated.
Abstract: The current study investigates the absorption kinetics of carbon dioxide (CO2) released from power plant exhaust using activated mixture of 2-amino-2-methyl-1-propanol (AMP) upgraded by piperazine (PZ). An absorption experiment of (AMP+PZ+H2O) was conducted in a wetted wall column absorber with a temperature variation of 298–313 K and CO2 partial pressure of 5–15 kPa. PZ is considered to be a rate promoter by adjustable mass proportion varying from 2 to 10 wt%, while the concentration of entire amine solution remained constant at 30 wt%. Based on the Zwitterions mechanism, an overall reaction pattern of (AMP+PZ+H2O) with CO2 was designed. Considering pseudofirst order reaction criteria, the kinetic rate factors and the overall second order rate constants were calculated. The overall rate constant (kOV) experienced a significant enhancement with a small addition of PZ into aqueous AMP solution. The observed second-order rate constants (k2, PZ) in this experimental study were 60,403, 81,925, 98,591 and 116,521 m3·kmol−1·s−1 at 298, 303, 308 and 313 K correspondingly. The experimental specific rate of absorption into (AMP+PZ+H2O) in connection with the model anticipated rate was determined with deviation of around 4.86% average absolute deviation (AAD).
TL;DR: In this article, the authors measured the permeation rates of gases (pure and mixed gas) within a novel nanocomposite membrane composed of poly tetramethyleneglycol (PTMG), hexamethylene diisocyanate (HDI), and diamine chain extender, 4,4-methylenebis(2-chloroaniline) (MOCA) at various silica loadings and operating conditions.
Abstract: Owing to the potential of polymeric and nanocomposite membranes for industrial application in CO2 capturing and gas separation processes, permeation properties of CO2, N2 and O2 through the polymer matrix have been an object of extensive research. We measured the permeation rates of gases (pure and mixed gas) within a novel nanocomposite membrane composed of poly tetramethyleneglycol (PTMG), hexamethylene diisocyanate (HDI), and diamine chain extender, 4,4-methylenebis(2-chloroaniline) (MOCA) at various silica loadings and operating conditions. The novel polyurethane was prepared by a two-step bulk polymerization technique based on the molar ratios of the used constituents 1 : 3 : 2 for PTMG: HDI: MOCA, respectively The FTIR spectra indicated that the extent of phase separation decreased by increase in the SiO2 content From the DSC and XRD analyses, the existence of small crystalline areas within the soft and hard segments of matrix was proved High thermal stability of new nanocomposites was authenticated by a 90 °C increase in the decomposition temperature upon including the SiO2 particles into the polymer matrix By providing a longer diffusion path, a reduction in the permeation of penetrants occurred after the incorporation of SiO2 content By raising the temperature from 25 to 45 °C, the gas permeation value of CO2, O2 and N2 rose steeply: 35, 54 and 81% in neat PU and 49, 64 and 137% in PU containing 15 wt%, respectively Conversely, the obtained results for increasing the feed gas pressure from 6 to 10 bar revealed that the penetration of non-condensable gases, O2 and N2, decreased while the permeation rate of CO2 polar gas surged dramatically Nevertheless, a simultaneous increment in the selectivity amounts of both gas pairs was revealed. For the gaseous mixtures, the trend of changes in permeability and selectivity values were almost identical with those of pure gas: decrease in permeation, and vice versa increase in gas pair selectivity Eventually the separation results of the prepared membranes indicated a strong tendency to move towards Robeson's line by incorporation of SiO2 nanoparticles into the matrix of membranes.
TL;DR: In this article, ultrasound/peroxymonosulfate/CuFe2O4 nanoparticles were synthesized and their properties were well determined by several advanced techniques, and the effects of pH, catalyst dosage, peroxymono-sulfate (PMS) concentration, and ultrasound (US) intensity were investigated on the decolorization.
Abstract: Sunset yellow (SY) dye removal from aqueous solution was assessed by ultrasound/peroxymonosulfate/CuFe2O4 nanoparticles. CuFe2O4 nanoparticles were synthesized and their properties were well determined by several advanced techniques. The effects of pH, catalyst dosage, peroxymonosulfate (PMS) concentration, and ultrasound (US) intensity were investigated on the decolorization. The best results (95.8% removal) were observed at pH=7, CuFe2O4= 25 mg/L, PMS=1.5 mM, US=200 W and 30 min. Nitrite and bicarbonate ions demonstrated high inhibition effect on the decolorization. PMS depicted high activity in the presence of CuFe2O4 compared to S2O
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and H2O2. Around 40% reduction in the decolorization was observed in reusability experiments. Sulfate and hydroxyl radicals were the major species of SY degradation based on quenching experiments. A mineralization of 50% was obtained only in 30min reaction time. This process can be effective for the destruction of organic dyes in colored wastewater.