Removal Efficiency Of Heavy Metals Research Articles

Effective Removal of Different Heavy Metals Ion (Cu, Pb, and Cd) from Aqueous Solutions by Various Molecular Weight and Salt Types of Poly-γ-Glutamic Acid.

In light of industrial developments, water pollution by heavy metals as hazardous chemicals has garnered attention. Addressing the urgent need for efficient heavy metal removal from aqueous environments, this study delves into using poly-γ-glutamic acid (γ-PGA) for the bioflocculation of heavy metals. Utilizing γ-PGA variants from Bacillus subtilis with different molecular weights and salt forms (Na-bonded and Ca-bonded), the research evaluates their adsorption capacities for copper (Cu), lead (Pb), and cadmium (Cd) ions. It was found that Na-bonded γ-PGA with a high molecular weight showed the highest heavy metal adsorption (92.2-98.3%), particularly at a 0.5% concentration which exhibited the highest adsorption efficiency. Additionally, the study investigated the interaction of γ-PGA in mixed heavy metal environments, and it was discovered that Na-γ-PGA-HM at a 0.5% concentration showed a superior adsorption efficiency for Pb ions (85.4%), highlighting its selectivity as a potential effective biosorbent for wastewater treatment. This research not only enlightens the understanding of γ-PGA's role in heavy metal remediation but also underscores its potential as a biodegradable and non-toxic alternative for environmental cleanup. The findings pave the way for further exploration into the mechanisms and kinetics of γ-PGA's adsorption properties.

Efficient removal of heavy metals in water utilizing facile cross-link conjugated linoleic acid micelles.

Micellar-enhanced ultrafiltration (MEUF) technology is an effective method to treat low-concentration heavy metal wastewater. However, the leakage of surfactants in the ultrafiltration (UF) process will inevitably cause secondary pollution. In this study, a biosurfactant of conjugated linoleic acid (CLA) with conjugated double bonds was selected to bind its micelles by simple thermal crosslinking to obtain morphologically stable stearic acid (SA) nanoparticles. The pure SA nanoparticles were obtained by repeated dialysis. The stability of the SA nanoparticles was verified by comparing the particle size distribution and solubility of the materials before and after crosslinking at different pH levels. The effectiveness of SA nanoparticle-enhanced UF in removing heavy metals was verified by exploring the adsorption performance of SA nanoparticles. The dialysis device was used to simplify the UF device, wherein SA nanoparticles were assessed as adsorbents for the elimination of Cu2+, Pb2+, and Cd2+ ions from aqueous solutions under diverse process parameters, including pH, contact time, metal ion concentration, and coexisting ions. The findings indicate that the SA nanoparticles have no evidence of secondary contamination in UF and exhibit compatibility with a broad pH range and coexisting ions. The maximum adsorption capacities for Cu2+, Pb2+, and Cd2+ were determined to be 152.77, 403.56, and 271.46 mg/g, respectively.

Application of coconut shell activated carbon filter in vertical subsurface flow constructed wetland for enhanced multi-metal bioremediation and antioxidant response of Salvinia cucullate

Coconut shell activated carbon (CNSAC) was applied as a filter layer in hybrid vertical subsurface flow constructed wetland (H-VSSF-CW), in order to enhance the multi-metal removal efficiency of the constructed wetland (CW) and to reduce heavy metal accumulation on Salvinia cucullata. Treatment P + AC, (having CNSAC filter layer), showed 32, 21 and 34% more Cd, Cr, and Pb removal efficiency than treatment P (without CNSAC layer). CNSAC activated carbon adsorbed Cd and Pb and Cr by functional groups –NH, -NO2, -C-O, –OH and –CO, and significantly reduced Cd and Pb exposure to S. cucullate. Chromium adsorption by CNSAC filter layer was half (just 25% of total input) of the Cd and Pb. In treatment P, due to high Cd, Pb and Cr accumulation in S. cucullate, the antioxidant defense mechanism of the plant was collapsed and cell death was observed, which in turn has resulted reduced biomass gain (5% reduction). On the other hand, in treatment P + AC, an antioxidant defense mechanism was active in the form significantly (p ≤ 0.05) increased of SOD, CAT and proline content while reduced MDA, EL, %EB and soluble sugar. So, the application of CNSAC increased the heavy metal removal efficiency of H-VSSF-CW by adsorption of a considerable share of heavy metal and hence, reduced the heavy metal load/exposure to S. cucullate.

Enhanced Crystallinity of MIL-53 (Fe) and Improved Pb2+ Ion Removal by MIL-53(Fe) in the Presence of TiO2

Water pollution due to improper disposal of various contaminants is one of the most serious threats faced by living beings all around the world. Lead (Pb) is a heavy metal which is commonly added to the environment by the industries such as battery manufacturing, paints etc. According to the world health organization, the maximum bearable Pb concentration of the human body is 70 μg dL- 1. However, in a contaminated water sample, this value could range from 200 to 500 mg L-1. Thus, the efficient removal of heavy metals from contaminated water is vital. Among various removal techniques available, adsorption plays a major role due to its high efficiency, low cost and ease of designing. MOFs are a class of crystalline porous adsorbent material that consists of a metal ion/cluster and an organic linker. Owing to their tailoring ability, high porosity, and high surface area they have been widely used in the removal of contaminants from wastewater. The main objectives of this study are to synthesize MIL-53 (Fe) MOF and MIL-53/TiO2 composite and determine the Pb (II) removal efficiency under light and dark conditions. MIL-53 (Fe) MOF was synthesized using iron (III) and 1, 4-dicarboxylic acid under solvothermal conditions. The composite was synthesized similarly in the presence of TiO2 nanoparticles. The successful synthesis of MIL-53 (Fe) MOF and MOF/TiO composite was confirmed by powder X-ray diffraction and Fourier-transform infrared spectroscopy. By the Debye−Scherrer equation, 79.06 nm and 65.46 nm of crystallite size were obtained by the MOF and the MOF/TiO22 composite. Atomic absorption spectroscopy was used to determine the metal ion concentration before and after adsorption. The optimum conditions for the Pb(II) removal are as; 50 mg L-1, 25 mg L-1 initial Pb ion concentration, 10 mg, 12.5 mg of adsorbent dose (for 25 ml of 50 mg L-1 Pb (II)) and 90 min, 90 min contact time for both adsorbents at light and dark conditions respectively. The pH of the solution was kept at a neutral level to ensure the reusability of wastewater after the removal of pollutants. The adsorption isotherms of both adsorbents were well fitted with the Langmuir model indicating the monolayer adsorption. Thus, at pH 7, 396.35 mg g-1 and 786.16 mg g-1 of maximum Pb (II) adsorption capacity were obtained by the MOF and the MOF/TiO2 composite respectively. Thus, a significant improvement in the Pb (II) ion removal was observed with the composite compared to the MOF. 
 Keywords: Adsorption, Heavy metal, Isotherm, MIL-53 (Fe)

Mn<sup>2+</sup> Adsorption on Nanozeolite: Determination of Thermodynamic Properties Using Isothermal Titration Calorimetry

This study investigates the thermodynamics of manganese ion adsorption on nanozeolite to assess the nanomaterial’s heavy metal removal efficiency from surface water, industrial water, and groundwater. Using Isothermal Titration Calorimetry (ITC), the thermodynamic profile of nanozeolite is obtained, demonstrating a low equilibrium binding affinity. The thermodynamic signature showed favorable binding mechanisms, primarily from the change of entropy, suggesting spontaneous reactions. Meanwhile, the enthalpy change of adsorption increases as temperature rises, while ∆G and T∆S decrease. Using proper thermodynamic conditions, nanozeolite may efficiently remove manganese from different water sources.

Efficient and Selective Removal of Heavy Metals and Dyes from Aqueous Solutions Using Guipi Residue-Based Hydrogel.

The presence of organic dyes and heavy metal ions in water sources poses a significant threat to human health and the ecosystem. In this study, hydrogel adsorbents for water pollution remediation were synthesized using Guipi residue (GP), a cellulose material from Chinese herbal medicine, and chitosan (CTS) through radical polymerization with acrylamide (AM) and acrylic acid (AA). The characteristics of the hydrogels were analyzed from a physicochemical perspective, and their ability to adsorb was tested using model pollutants such as Pb2+, Cd2+, Rhodamine B (RhB), and methyl orange (MO). The outcomes revealed that GP/CTS/AA-co-AM, which has improved mechanical attributes, effectively eliminated these pollutants. At a pH of 4.0, a contact duration of 120 min, and an initial concentration of 600 mg/L for Pb2+ and 500 mg/L for Cd2+, the highest adsorption capabilities were 314.6 mg/g for Pb2+ and 289.1 mg/g for Cd2+. Regarding the dyes, the GP/CTS/AA-co-AM hydrogel displayed adsorption capacities of 106.4 mg/g for RhB and 94.8 mg/g for MO, maintaining a stable adsorption capacity at different pHs. Compared with other competitive pollutants, GP/CTS/AA-co-AM demonstrated a higher absorption capability, mainly targeted toward Pb2+. The adsorption processes for the pollutants conformed to pseudo-second-order kinetics models and adhered to the Langmuir models. Even after undergoing five consecutive adsorption and desorption cycles, the adsorption capacities for heavy metals and dyes remained above 70% and 80%. In summary, this study effectively suggested the potential of the innovative GP/CTS/AA-co-AM hydrogel as a practical and feasible approach for eliminating heavy metals and dyes from water solutions.

Enhanced Heavy Metal Removal from Wastewater Produced by Chemical Analysis Laboratory Using Calcium Oxide Precipitation: pH Improvement and Characterization of Precipitated Phases

This article presents research results on the precipitation of heavy metals: Aluminum (Al), arsenic (As), cadmium (Cd), zinc (Zn), iron (Fe), chromium (Cr), copper (Cu), nickel (Ni), vanadium (V), and molybdenum (Mo) from wastewater generated in mining chemical analysis laboratory. Calcium oxide was used as the precipitating agent. The efficiency of heavy metal removal was achieved by increasing the dosage of precipitating reagent (8-28 g/L). Efficiencies greater than 90% are achieved. The efficiency of chemical precipitation depends on the pH of the process. Over a wide pH range from 6-11, the removal efficiency of zinc, iron, cadmium, and arsenic were approximately 99.9%. The optimum pH range for the removal of most elements was found to be between 8 and 11, where the removal efficiency of heavy metal ions reached up to 99%. Furthermore, X-ray diffraction results indicated that the metals in the wastewater precipitated in various forms as mentioned in Table 7, and not just as hydroxides, due to the presence of different ions in the solution.

Sustainable Industrial Wastewater Treatment and Antibacterial Activity using Environmental Friendly Ferrite Nanoparticles

A comparison studies of two unique bimetallic spinel ferrite nanoparticles synthesized by the sol-gel process, namely Co-NiFe2O4 andCu-ZnFe2O4 were investigated. Various characterization approaches were utilized to examine the structural, morphological, magnetic and electrical characteristics of the nanoparticles. Both Co-NiFe2O4 and Cu-ZnFe2O4 nanoparticles formed single-phase spinel structures, according to X-ray diffraction (XRD) research whereas FTIR spectra provided information about the vibrational modes and chemical bonding within the nanoparticles confirmed the presence of desired metal-oxygen bonds chemical bonding within the nanoparticles. The UV-Vis spectroscopy revealed the optical absorption properties of the nanoparticles indicating the presence of energy bandgaps in the visible range. Scanning electron microscopy (SEM) images suggested the uniform and well-dispersed nanoparticles with average sizes in the nanoscale range. Vibrating sample magnetometry (VSM) measurements demonstrated that both Co-NiFe2O4 and Cu-ZnFe2O4 nanoparticles exhibited ferromagnetic behaviour at room temperature. The saturation magnetization values were found to be higher for Co-NiFe2O4 nanoparticles compared to Cu-ZnFe2O4 nanoparticles, suggesting the superior magnetic properties of the former. As a result, ferrites demonstrate promise in industrial wastewater treatment, facilitating efficient heavy metal removal and advanced organic pollutant degradation, contributing to a sustainable and effective solution. The antibacterial efficacy of synthesized bimetallic ferrite nanoparticles against Salmonell typhi, Escherichia coli, Staphyloccus aureus, Bacillus cereus proves that the synthesized ferrite nanoparticles possess a good antibacterial activity against the selected pathogens.

Efficient Cu(II) removal with boronated zero-valent iron via inhibition of oxygen adsorption and enhanced electron transfer

The inhibition of electron transfer by the iron oxide passivation layer and the competition of oxygen for electrons limited the efficiency of heavy metal removal by zero-valent iron reduction. Herein we synthesized micron zero-valent iron modified with boric acid by mechanical ball milling, and demonstrated its enhanced copper ions removal performance. Compared to pristine ZVI, B-ZVI is approximately 2.6 times more efficient in the removal of copper. Interestingly, copper removal was significantly inhibited under air atmosphere for pristine ZVI. However, for B-ZVI, copper removal efficiency was almost insignificantly different between air and argon atmosphere conditions. Furthermore, the modification of ZVI with boric acid promoted the Cu(II) reduction proportion. Boronated modification effectively inhibited oxygen competition for electrons in removing heavy metals by zero-valent iron, which was conducive to the improvement of the heavy metal removal efficiency and the electron utilization of zero-valent iron. This study elucidated the importance of surface modification on the reactivity of micron-sized zero-valent iron and provided an efficient heavy metal removal strategy with zero-valent iron for environmental remediation.

MXene sheets surface constructed a strong hydrogel coating for sustainable oily wastewater separation

Membrane separation technology can effectively address the issues of high energy consumption and low efficiency encountered in traditional separation processes. However, oil fouling hinders the widespread adoption of membrane technology in the field of oil-water separation. Therefore, preventing membrane fouling is crucial for overcoming this bottleneck. Titanium carbide (Ti3C2Tx, MXene), a recent addition to the two-dimensional material family, has garnered significant interest in the domain of water treatment owing to its controllable surface groups, hydrophilic nature, antimicrobial properties, and high electrical conductivity. Hence, we proposed a strategy to construct hydrogel coatings on carboxylated MXene surfaces. Moreover, the rigidity of the hydrogel framework was further improved by introducing CaCO3 nanoparticles. A stronger hydrogel layer ensured that the hydration layer is difficult to contaminate with oil and the fastness of the membrane material. Naturally, the as-prepared membrane showed excellent separation performance for a wide range of emulsions, maintaining high levels (3979.5 L m–2 h−1 bar−1 and 99.96 %) after 5 consecutive separation cycles of 200 min. Additionally, the membrane separated emulsions containing acids, salts, or alkali with a permeability of 2982.8 L m–2 h−1 bar−1 after 40 min; it also treated actual oily wastewater achieving a permeability of 238.9 L m–2 h−1 bar−1 and showed high removal efficiency (>99.9 %) for several heavy metals (Cu, Li, Pb, Se, and V), as well as antimicrobial (92.5 %) properties that enhance its potential for industrial applications. This study offers a new idea for designing anti-oil-fouling MXene oil-water separation membranes.

Electro-catalytic ozonation of contaminants in landfill leachate: Optimization by BBD, economic evaluation, mechanism, and reaction pathway

An electro-catalytic ozonation process with ZnO nano-granules as a catalyst (CFR-EC/O3-UV@ZnO process) was developed to treat raw landfill leachate. LC-MS analysis was applied to determine organic compounds. After CFR-EC/O3-UV@ZnO process, COD, TOC, BOD5, NH4+-N, P-PO4−3, color, and turbidity were reduced to 90.9%, 89.4%, 89.1%, 89.5%, 87.7%, 99.1%, and 99.7%, respectively under the optimum conditions of 10 g.hr−1 O3 dosage, pH 11.0, and 0.006 L.min−1 flowrate. At the same conditions removal efficiencies of heavy metals (HMs): Cr6+, Pb2+, As3+, Mg2+, B3+, Mn3+, Ni2+, Ba2+, Hg2+, Co2+, Fe2+, and Li+ were obtained 90%, 84.7%, 90%, 99%, 83.7%, 95%, 20%, 75%, 91%, 90%, 78% and 60%, respectively. In spite of high COD and BOD5 removal efficiencies, the process could not remove two organic substances including diphenylamine and 2,2,4-trimethyl-1,3-pentanediol. A high R2 value of 0.99 demonstrated the accuracy of the selected model. Economic evaluation depicted that the current process cost 0.95 $.m−3. Finally, this process is suggested for the treatment of landfill leachate with relatively high efficiency.

Investigation of nanofiltration systems efficiency for removal of chromium and copper from groundwater resources

AbstractThere is a vital need and constraint for providing water of good quality all around the world. Thus, with the aim of groundwater treatment, different methods of water treatment have been reviewed. Considering modern methods of membrane filtration, in this study efficiency of nanofiltration for removing heavy metals (copper and chromium) has been examined. The investigation has been accomplished in two separate phases for removing copper and chromium. To prepare the samples of groundwater, urban waters have been utilized and for preparation of chromium‐contaminated and copper‐contaminated waters, powder of chromium‐oxide and powder of copper sulfate pentahydrate have been added into samples, respectively. In this research, system‐operating pressure has been changed, while concentration and pH were kept constant. The effect of pressure on the efficiency of heavy metals removal has been checked and optimum pressure of the process has been achieved. Then, with optimal pressure as system operating pressure, the removal of heavy metals in different pH have been checked and accordingly, the optimal pH for the process was obtained. The Optimum Pressure and pH for chromium and copper are 7.5 bars and 6.3, and 7.5 bars and 6.7, respectively. Taking into account the result of this study, Nano filtration is a suitable method with high efficiency (90% and higher in optimum pressure and pH) for the removal of heavy metals from groundwater.

Comparison of Pb2+ Adsorption Properties of Biochars Modified Through CO2 Atmosphere Pyrolysis and Nitric Acid

Acid modification has been widely used to modify the structural properties of biochars. However, acid modification led to the large consumption of acid, increased difficulty of waste effluent disposal, and a high application cost. To evaluate the advantages and application potential of biochars prepared under CO2, utilizing pyrolysis to directly modify biochars to improve heavy metal removal efficiency and reduce production cost, would be an important prerequisite for the broad application of biochars. The sorption performance of Pb2+ with CO2-modified biochars was compared with that of HNO3-modified biochar. The elemental compositions and structural properties of biochars were characterized through elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results revealed that for biochars produced at 500℃, HNO3 modification produced abundant carboxylic groups and -NO2 (asy) and -NO2 (sym) groups, promoting the surface activities and complexing abilities of biochars. The CO2-modified biochars contained abundant carbonate minerals, which could remove Pb2+ by electrostatic ion exchange and coprecipitation or complex. In addition, compared to that of HNO3-modified biochars, CO2-modified biochars had the larger specific surface area and better microporous structures, which were beneficial to the diffusion of Pb2+ and further promoted surface sorption. CO2 modification increased the maximum Pb2+ sorption capacity of W500CO2 and W700CO2, which were 60.14 mg·g-1 and 71.69 mg·g-1. By contrast, HNO3-modified biochars W500N2-A and W700N2-A showed the lower Pb2+ sorption capacities, which were 42.26 mg·g-1 and 68.3 mg·g-1, respectively. The increasing of the specific surface area and functional groups simultaneously promoted the sorption capacity of CO2-modified biochars. Consequently, the CO2-modified biochar had the advantages of low cost, environmental friendliness, and high heavy metal removal efficiency, which is a modification method worthy of promotion and application.

Emission characteristics and removal of heavy metals in flue gas: a case study in waste incineration and coal-fired power plants.

Heavy metal pollutants such as Hg, As, Pb, Cr, and Cd emitted from coal and waste combustion have received widespread attention. In this study, we systematically investigated the emission characteristics of heavy metals in waste incineration and coal-fired flue gases, focused on testing the removal effect of self-made cold electrode electrostatic precipitator (CE-ESP) on heavy metals in flue gas, and made a comparative analysis with the existing air pollution control devices (APCDs). Test results from waste incineration power plant showed that each APCD showed a certain effect on the removal of heavy metals in condensable particulate matter (CPM), with an average removal efficiency of bag filter was 86%, but its effect on Hg removal was slightly worse. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiency of CE-ESP on heavy metals in CPM was as high as 93%, including 76% for Hg. The removal efficiency of heavy metals (especially Hg) in CPM increased with the increase of flue gas temperature difference between inlet and outlet of CE-ESP. Test results from this coal-fired power plant showed that heavy metals were enriched in fly ash to a higher degree than in slag, the synergistic control of heavy metals in submicron particulate matter by the dust remover was not obvious, and there was a significant correlation between each heavy metal emission factor and its content in coal. Under the temperature field with non-electric cold electrode plate operation mode, the overall effect of CE-ESP on the removal of gaseous heavy metals was better than that of particulate heavy metals. Under the conventional electric field operation mode, CE-ESP was less effective in removing particulate Cr and gaseous Hg0. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiencies of CE-ESP for particulate and gaseous heavy metals were 82.37% and 76.16%, respectively.

Investigation into the Optimization Process of Adsorbent Dosage on Heavy Metal Removal

Heavy metals represent pervasive environmental hazards, posing significant threats to human health and ecological balance owing to their enduring presence and toxic nature. Addressing the removal of heavy metals from Ahmadu Bello University’s wastewater stabilization pond (WSP) which was designed to handle the organic pollutants and heavy metals found in the university's generated wastewater, stands as a critical imperative in curtailing these deleterious impacts. Employing adsorption techniques with appropriate adsorbents emerges as a promising avenue for achieving efficient heavy metal removal. This study delves into the optimization of adsorbent dosage using pH of 7.0 condition to study the efficiency of cadmium removal as the selected response, whose optimum variables were used to investigate the effect of pH variation and time for the removal efficacy of other heavy metals, specifically chromium, lead, and copper from WSP. Leveraging a design of experiments approach, the corn cob adsorbent dosage (ranging from 10 to 20 g) and concentrations of cadmium heavy metal solutions (ranging from 20 to 100 g) were varied, utilizing Design Expert software, aimed at pinpointing the optimal dosage and assessing adsorption capacities. The experimental findings underscore the pivotal role of optimized adsorbent dosage and pH conditions in enhancing the efficiency of heavy metal removal from the WSP. The optimum corn cob adsorbent dosage of 15 g exhibited commendable cadmium heavy metal removal efficiency which was selected for optimization study among the other identified heavy metals present in the WSP used, reaching 94.8 % at the end of 98th days. Furthermore, the investigation revealed that peak adsorption efficiencies at the end of study period of 98th days for chromium, lead, and copper were attained at a neutral pH of 7.0, yielding removal percentages of 94.5 %, 93.6 %, and 93.6 %, respectively. In conclusion, these insights emphasize the critical importance of systematically fine-tuning adsorbent dosage and pH conditions to maximize heavy metal removal efficacy.

Hydrophobic deep eutectic solvents characterization and performance for efficient removal of heavy metals from aqueous media

In this study, we successfully extracted copper, cobalt, and nickel metals from aqueous media using hydrophobic deep eutectic solvents (DESs). The DESs designed for this research consisted of a combination of carboxylic acids, namely Octanoic acid, Nonanoic acid, Decanoic acid, and Dodecanoic acid. Before and after the extraction process, the prepared DESs underwent comprehensive characterization using various analytical techniques. Viscosity measurements demonstrated that the prepared solvents exhibited low viscosity at room temperature, making them well-suited for extraction processes. Moreover, Karl Fischer Titration was employed to accurately determine the water content, which is crucial for evaluating hydrophobicity. We investigated the influence of various parameters on the metal extraction yield, including the initial concentration, temperature, and time. Under optimized conditions, using Dodecanoic acid + Octanoic acid as the most efficient DES, extraction yields of 85.61 % for Cu, 96.19 % for Co, and 76.54 % for Ni were achieved. Furthermore, through approximately three extraction steps, complete removal of metal ions from the aqueous medium was achieved. Due to its superior performance, the DES composed of Dodecanoic acid + Octanoic acid was selected for further investigations. The DESs exhibited favorable characteristics such as low viscosity and hydrophobicity, positioning them as promising for extraction in aqueous environments.

Improvement of hybrid polyvinyl chloride/dapsone membrane using synthesized silver nanoparticles for the efficient removal of heavy metals, microorganisms, and phosphate and nitrate compounds from polluted water.

Heavy metals exist in different water resources and can threaten human health, inducing several chronic illnesses such as cancer and renal diseases. Therefore, this work dealt with the fabrication of highly efficient nanomembranes based on silver nanoparticle (Ag NP)-doped hybrid polyvinyl chloride (PVC) by dapsone (DAP) using an in situ method. Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis were used to confirm the hybridization of PVC as well as the crystalline structure of hybrid PVC nanocomposites. Three varying proportions of Ag NPs (i.e., 0.1, 0.2, and 0.3%) were used to fabricate hybrid PVC-DAP nanomembranes. The Brunauer-Emmet-Teller (BET) method was used to estimate membrane surface area, porosity and distribution of pore volume. The mechanical strength and antibacterial properties of the cased films notably improved when Ag NPs were added depending on the NP ratio inside the matrix. Results obtained from adsorption experiments of PVC-DAP nanomembranes at 35 °C revealed that the optimum nanomembrane was achieved at 0.2% NPs and its percentage of removal effectiveness ranged from 71 to 95% depending on the ion type. The surface morphology of the PVC-DAP-0.2 Ag NPs before and after the adsorption process of the metal ions was analyzed using SEM-EDX. Moreover, the impact of other parameters such as the initial concentrations, pH media, temperature, and contacting time, on the adsorption efficiency of PVC-DAP-0.2 Ag NPs was also investigated. Furthermore, kinetic and adsorption isotherm models were suggested to describe the adsorption efficiency of the PVC-DAP-0.2 Ag NP membrane, and the uptake mechanism of metal ion removal was studied. The obtained outcomes for these fabricated nanomembranes demonstrated that they could be potential candidates for water purification and other potential purposes including biomedical areas.

Potential of ash from agricultural waste as substitute of commercial FeCl3 in primary treatment of landfill leachate

Due to the ever increasing global population, higher volumes of industrial waste discharges to landfill have caused major problems for the environment. This study investigated the performance of rice straw ash (RSA) as a natural coagulant under different conditions for the treatment of landfill leachates by coagulation-flocculation and microfiltration, with and without addition of FeCl3. The highest performing treatment conditions (RSA = 2.48 g/L, FeCl3 = 4.98 g/L, settling time = 54.75min) were achieved with the combined use of RSA and FeCl3 as coagulant and led to a sludge volume index of 41.65 mL/g, 51.27% COD removal and 76.48% total suspended solid removal. In contrast, FeCl3 alone achieved slightly better COD and total suspended solid removal rates, however it resulted in higher sludge volume index and sludge production. The combined use of RSA and FeCl3 reduced the consumption of these two coagulants by 78.76% and 46.69% respectively. Functional groups and thermal stability of the flocs showed that RSA + FeCl3 synergistically enhance the mechanisms of the coagulation-flocculation process, including adsorption by particle's bridging, charge neutralization and size of flocs. Combining the coagulants resulted in increased van der Waals forces and lower attractive forces of the inter-colloidal energy barrier in the leachate. Additionally, the highest and lowest heavy metals removal rates for treatment by microfiltration were found for Fe (92.15%) and Mg (7.63%), with a total heavy metals removal efficiency in the range of 6.08–90.78%. The findings of this study show that RSA can serve as a natural eco-friendly coagulant both alone and in combination with FeCl3 in the leachate treatment.

A concise review on wastewater treatment through microbial fuel cell: sustainable and holistic approach.

Research for alternative sources for producing renewable energy is rising exponentially, and consequently, microbial fuel cells (MFCs) can be seen as a promising approach for sustainable energy production and wastewater purification. In recent years, MFC is widely utilized for wastewater treatment in which the removal efficiency of heavy metal ranges from 75-95%. They are considered as green and sustainable technology that contributes to environmental safety by reducing the demand for fossil fuels, diminishes carbon emissions, and reverses the trend of global warming. Moreover, significant reduction potential can be seen for other parameters such as total carbon oxygen demand (TCOD), soluble carbon oxygen demand (SCOD), total suspended solids (TSS), and total nitrogen (TN). Furthermore, certain problems like economic aspects, model and design of MFCs, type of electrode material, electrode cost, and concept of electro-microbiology limit the commercialization of MFC technology. As a result, MFC has never been accepted as an appreciable competitor in the area of treating wastewater or renewable energy. Therefore, more efforts are still required to develop a useful model for generating safe, clean, and CO2 emission-free renewable energy along with wastewater treatment. The purpose of this review is to provide a deep understanding of the working mechanism and design of MFC technology responsible for the removal of different pollutants from wastewater and generate power density. Existing studies related to the implementation of MFC technology in the wastewater treatment process along with the factors affecting its functioning and power outcomes have also been highlighted.

Comparison of Three Materials Derived from Waste EPS for Heavy Metal Removal Efficiency

Comparison of Three Materials Derived from Waste EPS for Heavy Metal Removal Efficiency