Removal Efficiency Of Pb Research Articles

Methylthiazole Schiff base functionalized SBA-15 for high-performance Pb(Ⅱ) capture and separation

Selective recovery of Pb(II) from effluent reduces its toxic impact on environment and benefits for saving non-renewable lead resources. To capture and separate Pb(II), a kind of methylthiazole Schiff base modified mesoporous silica, denoted as MTCI-SBA-15, was fabricated via grafting amino groups onto SBA-15 which was followed by Schiff condensation with 4-methylthiazole-5-carboxaldehyde. A variety of characteristic methods monitored the evolution of the modified adsorbent. Pb(II) uptake to MTCI-SBA-15 was studied in batch mode concerning pH, contact time, initial concentration, temperature, coexisting metallic ions, etc. Kinetic analyses revealed that the pseudo-second-order model was suitable for describing adsorption process. The adsorption isotherms were well represented by the Langmuir model. The thermodynamic study confirmed that the sorption was spontaneous and endothermic. The maximal load ability of MTCI-SBA-15 (283 mg g−1) for Pb(II) outperformed that of most modified mesoporous silica adsorbents. Moreover, Pb(II) removal efficiency higher than 99% can be reached with a low initial concentration (<50 mg L−1). Testing on the effects of competing ions suggested that MTCI-SBA-15 exhibited a desirable selectivity for Pb(II). Further, MTCI-SBA-15 was recyclable, retaining 93.1% of the adsorption capacity after five successive cycles. Mechanisms investigation indicated that the imine N atom on the Schiff base and the S atom on the 4-methylthiazole ring played a synergistic role during the adsorption process for Pb(II). The MTCI-SBA-15 showed excellent application potential for Pb(II) capture and separation.

Simultaneous removal of multiple heavy metals using single chamber microbial electrolysis cells with biocathode in the micro-aerobic environment

The simultaneous and efficient removal of various heavy metals from wastewater to satisfy the requirements of zero discharge has been a research hotspot and difficult point. In the laboratory scale (0.5 L), the biocathode microbial electrolytic cells (BCMECs) were constructed with the pre-screened heavy metal-tolerant electroactive bacterial, mainly of the Sphingomonas, Azospira and Cupriavidus. The BCMECs system showed a more satisfactory removal effect for multiple heavy metals and organic pollutants. At the auxiliary voltage of 0.9 V and initial concentration of 20 mg L−1, the removal efficiency of Cu, Pb, Zn, Cd and COD were 98.76 ± 0.32%, 98.01 ± 0.76%, 73.58 ± 4.83%, 84.39 ± 5.95%, 77.55 ± 1.51%, respectively. It was found by various characterization techniques (CV, EIS, XPS et al.) that the constructed biocathode has the function of electrocatalytic reduction of heavy metal ions in a micro-aerobic, film-free environment. The positive shift (0.030–0.229 V) of the initial potential for heavy metal reduction and the absence of a significant increase (＜ 10 Ω) in the interfacial resistance indicated a reduction in the total free energy of the reduction reaction, which promotes the reaction and improves the efficiency of heavy metal removal. Bacterial community analysis revealed that the Proteobacteria has been dominant in different heavy metal environments. With the increase of heavy metal concentration, Sphingomonas, Azospira and Cupriavidus showed stronger tolerance and became the dominant genus. This study emphasized the important performance of biocathodes and the effective treatment of heavy metal wastewaters by BCMECs and provided a reasonable way for industrial and mining enterprises to innovate the water treatment process.

Hyperbranched Dithiocarbamate-Modified Biochar: A Promising Adsorbent for Selective Removal of Pb(II) from Wastewater

Herein, dithiocarbamate-modified biochar (BC-HDTC) was successfully synthesized with nitric acid (HNO3), thionyl chloride (SOCl2), branched PEI and carbon disulfide (CS2). The effective anchoring of amine and dithiocarbamate groups onto the surface of the biochar was proven by SEM, FTIR, XPS, N2 adsorption–desorption experiment. The batch experiments demonstrated BC-HDTC can selectively remove 98% Pb(II) within multi-metals solution when pH = 5, T = 30 °C. The impact of variations on the BC-HDTC were researched (pH, contact duration, Pb(II) original concentration).The sorption kinetics (pseudo-first-order, pseudo-second-order, intra-particle diffusion model) and isotherm modeling (Langmuir, Freundlich, and tempkin models) of Pb(II) on BC-HDTC were investigated. The adsorption process was depicted to attain equilibrium in less than 20 min and to fit the Langmuir isotherms and pseudo-2nd-order kinetics satisfactorily. The complexation of functional groups of HDTC (amine/imine and dithiocarbamate) with Pb(II) as well as the ion exchange between Na(I) and Pb(II) are the main adsorption mechanisms. Pb(II) onto BC-HDTC was endothermic and spontaneous, according to thermodynamic parameters. After 4 consecutive adsorption-desorption cycles, Pb removal efficiency of BC- HDTC remained over 90%. This work revealed the significant potential for Pb(II) contamination of BC-HDTC, a valuable and reusable adsorbent.

Removal efficiency of Pb(ii) by coal fly ash cenospheres@carbon nanotubes

High defect density CSs@CNTs with a 3D network structure were grown in situ on the surface of solid waste CSs by CVD. The prepared CSs@CNTs had a maximum adsorption capacity of 36.01 mg g−1 at pH = 6.

Odstranjevanje potencialno strupenih kovin iz odpadnega blata iz čistilne naprave z uporabo EDTA

Odpadno blato iz čistilnih naprav (ČN) ima zaradi velike hranilne vrednosti potencial za uporabo v kmetijstvu, vendar je pogosto onesnaženo s potencialno strupenimi kovinami (PSK). V raziskavi smo preverili ali ReSoil® tehnologija, ki temelji na uporabi EDTA (50, 70 in 100 mmol l-1), omogoča učinkovito odstranjevanje PSK iz odpadnega blata, vzetega po aerobni (blato1) in anaerobni (blato2) biološki obdelavi. Največji delež odstranitve Pb smo dosegli v blatu1 (do 60 %), največji delež odstranitve Zn in Cu pa v blatu2 (do 55 in 29 %). Vsebnost hranil se po remediaciji ni bistveno spremenila, le vsebnost dostopnega fosforja se je v blatu2 po remediaciji do 1,7-krat zmanjšala, vendar je še vedno ostala velika (489-510 mg 100-1 g-1). Po remediaciji so bile koncentracije v izpirkih za vse kovine, razen za Zn, pod mejo za nenevarne snovi. Za dokazovanje možnosti recikliranja procesnih raztopin in EDTA smo blato2 oprali s 50 mmol l-1 pralno raztopino v seriji 5 zaporednih remediacij in pri tem v povprečju odstranili 28 % Pb, 48 % Zn, 35 % Cu, 30 % Mn in 10 % Fe. ReSoil® tehnologija sicer omogoča odstranjevanje PSK iz blata in pri tem ohrani njegovo hranilno vrednost, vendar je učinkovitost tehnologije odvisna od postopkov obdelave blata na ČN.

Non-Linear Regression Model for Estimating the Efficiency of Heavy Metals Removal by Soil Washing with Chitosan Solution

The process of heavy metals removal by soil washing using chitosan as washing agent is a multivariate problem. According to the experimental data sets obtained during experiments performed at laboratory scale, the main parameters that influenced the efficiency of the soil washing process were the stirring time of the polluted soil with the investigated washing agent, washing solution concentration, and solid/liquid ratio (S/L ratio). This study explores the statistical relationships between the removal efficiency of Cu and Pb from polluted soil by washing with chitosan and factors influencing the soil washing process by use of a non-linear regression model. The non-linear regression model contains a non-linear component and a component of interaction among the two parameters (S/L ratio “X1”, the stirring time “X2”) which influences the efficiency of the Cu and Pb removal from soil by soil washing with the investigated washing agent. The proposed model is useful for predicting and estimating the effectiveness of the soil decontamination process by washing with chitosan. A comparison between the data calculated using the proposed mathematical model and the experimental data was also performed in order to determine the integrity and conformity of the mathematical model obtained. The results showed a good fit of the obtained model to the experimental data.

Macroporous honeycomb-like magnesium oxide fabricated as long-life and outstanding Pb(II) adsorbents combined with mechanism insight.

The macroporous honeycomb-like MgO (MHM) had been successfully prepared by hard template method using polystyrene (PS) spheres with different particle sizes of about 400, 600, and 800nm, respectively. The adsorption performance (3700, 3470, and 3087mg/g) and specific surface areas (64.0, 51.4, and 34.4 m2/g) of MHM materials were inversely proportional to their pore diameters. Among the prepared MHM materials, MHM-400 exhibited the most excellent adsorption performance of 3700mg/g towards Pb(II) at 25°C. In this study, the macropore size in MHM played a major role in the adsorption process; Dubinin-Radushkevich (D-R) model further indicated that Pb(II) removal by MHM-400 was dominated by chemical adsorption. The thermodynamic analysis (ΔG0 < 0, ΔH0 > 0, and ΔS0 > 0) revealed that the Pb(II) adsorption was spontaneous and endothermic. After storing for 360days, the Pb(II) removal efficiency of MHM-400 was still higher than 98.2%, exhibiting ultra-long life for Pb(II) capture. MHM-400 also exhibited high anti-interference ability towards typically coexisting ions (Na+ and K+). According to the density functional theory (DFT) calculation, the Pb could be adsorbed on the top site of the oxygen atom at the surface of the cubic MgO (200) plane; the adsorption energy (Ead) was 0.159eV. The XRD and FTIR analyses revealed the further formation of Pb3(CO3)2(OH)2 and PbO after Pb(II) adsorption. Furthermore, MHM-400 could effectively remove both Cd(II) and Pb(II) ions from wastewater within 20min, and the adsorption efficiency achieved > 99%, suggesting that MHM-400 was a potential material for effective Pb(II) removal.

Sugarcane Bagasse and Corn Stalk Biomass as a Potential Sorbent for the Removal of Pb(II) and Cd(II) from Aqueous Solutions

Heavy metal pollution in the water supply is a serious environmental problem that affects human health around the world. The goal of this study was to investigate the adsorption behaviour of sugarcane bagasse (SB) and corn stalk (CS) biomass for Pb(II) and Cd(II) removal from metal-contaminated water. When the doses of biomass were increased in solutions containing Pb(II) and Cd(II), the SB and CS showed a trend of increasing metal removal efficiency. The removal efficiency of biomass for Pb(II) decreased as the pH of the solution increased from 5.0 to 7.0, with an optimum pH range of 5 to 6. However, pH has little influence on the removal efficiency of biomass for Cd(II). Adsorption equilibrium is reached in about 15 min. Adsorption for at least four cycles improves Pb(II) removal efficiency (up to 98 %) in solutions containing only Pb(II). The best fitness of the adsorption isotherm to Freundlich suggests multilayer adsorption of metal ions onto CS. Higher qmax and Kf suggest that SB and CS have a greater affinity for Pb(II) than for Cd(II). Pb(II) adsorption potential was found in biomass derived from SB and CS, but it was less effective as a Cd(II) adsorbent. For application in environmental clean-up, we suggest further study on the structural modification of biomass to enhance its metal removal capacity, the regeneration of biomass for better results, and field trials for practical application. HIGHLIGHTS The adsorption behaviour of sugarcane bagasse and corn stalk biomass for Pb(II) and Cd(II) removal from metal-contaminated water was studied The removal efficiency of Pb(II) increases with increased doses of biomass and decreases with increased solution pH and metal initial concentrations Adsorption for at least four cycles improves metal removal efficiency in the case of Pb(II) Freundlich’s isotherm suggests multilayer adsorption of Pb(II) and Cd(II) onto corn stalk biomass Higher qmax and Kf values suggest that sugarcane bagasse and corn stalk have a higher affinity for Pb(II) than Cd(II)

Preparation, characterization and magnetic properties of Sm0.95Ho0.05FeO3 nanoparticles and their application in the purification of water

Sm0.95Ho0.05FeO3 was successfully prepared in a single phase using the citrate combustion method. The investigated sample was characterized using X-ray diffraction (XRD), a high-resolution transmission electron microscope (HRTEM) and X-ray photoemission spectroscopy (XPS). XRD confirmed that the sample was synthesized in an orthorhombic phase with an average crystallite size of 12 nm. HRTEM indicated that the sample was prepared in the nanoscale with an average particle size of 18 nm. XPS was used to identify the chemical bonds, binding energies and core levels of Sm0.95Ho0.05FeO3. The magnetic properties were studied using a vibrating sample magnetometer and DC magnetic susceptibility using Faraday’s method. The sample has an antiferromagnetic behavior with weak ferromagnetic components. The presence of magnetic Ho3+ ions in the SmFeO3 sample causes the magnetic exchange interaction between the 2p orbital of Fe3+ and the 4d sub-shell of Ho3+ ions. The dependence of pH value on the removal efficiency of Pb2+ from water was studied. The maximum Pb2+ removal efficiency of the Ho-doped SmFeO3 nano perovskite is 26% at pH = 5 and 99% at pH = 8. The Freundlich, Langmuir and Temkin isotherms were studied to understand the adsorption mechanism. The Temkin adsorption isotherm best fitted with the experimental data.

Synthesis of Quaternary Ammonium Tannin from Paper Mill Wastewater for Application in Water Treatment

Total tannins were separated and recovered from paper mills wastewater by distributed extraction and used as a raw material to synthesize quaternary ammonium tannate through the Mannich reaction. Quaternary ammonium tannins are used as coagulants and flocculants in wastewater treatment. The structural and properties of the quaternary ammonium tannate materials were determined by FTIR infrared spectroscopy, SEM scanning electron microscopy, DSC-TGA thermal analysis and determine the point of zero charge-pHpzc. The experiment to evaluate the coagulation and flocculation ability of the quaternary ammonium tannate in wastewater treatment was performed using the Jartest device model and evaluated through the removal efficiency of Pb2+ and Cd2+ metal ions, turbidity and DO index. The DO index and turbidity of the wastewater sample are best treated with quaternary ammonium tannin content in the range of 0.5-1%, the time for coagulation and flocculation is 30 minutes. The removal efficiency of metal ions Pb2+ and Cd2+ reached 92% and 75% respectively in the pH range from 5-7 with the input ion concentration of 50 ppm.&#x0D; &#x0D; &#x0D; &#x0D;

Heavy metal contaminated soil remediated by a bioelectrochemical system: Simultaneous promotion of electrochemically active bacteria and bipolar membrane

A modified microbial electrolysis desalination cell (BP–C-MEDC) equipped with a bipolar membrane (BPM) and a cation exchange membrane (CEM) was fabricated to efficiently remove heavy metals from polluted soil, compared with microbial electrolysis desalination chemical-production cell and conventional MEDC at various solid-to-liquid (S/L) ratios. At optimal 0.1 g/mL of S/L ratio, the BP-C-MEDC showed the highest current density due to BPM application to alleviate the acidification of the anode chamber and obtain the lowest resistance. Simultaneously, the lowest desalination efficiency (3.88 ± 1.73%) of the BP-C-MEDC led to less weight loss in the soil at the S/L ratio due to less self-diffusion induced by anion exchange membrane loss. The BP-C-MEDC had negligible organics pollution, where the total organic carbon concentration of the cathode chamber was only 5.2 ± 0.6 mg/L after 12 h of treatment with the S/L ratio. The lowest pH and the highest current density derived from the direct application of BPM brought about the highest removal efficiencies of Cd (81.10%), Pb (23.05%), and Zn (30.14%) at the S/L ratio of the BP-C-MEDC, along with the lowest energy consumption of metal removal. The results suggest that the proposed system has the potential to efficiently treat heavy metals and inefficiently release organics from the contaminated soil.

Synthesis, Analytical and Uptake Behavior of Copper, Cadmium and Lead by New Schiff-base Chelating resin

The current study aims to improve the quality of wastewater collected from the raw, primary sedimentation tank and secondary sedimentation tank of Hamdan wastewater treatment plant, Basrah, Iraq. Heavy metals contamination is one of the most critical environmental issues. Therefore, appropriate steps need to reduce pollutants in wastewater to acceptable levels before being discharged to the environment. Several treatment methods have been developed recently to adsorb these pollutants. This study reviews the ability of polymer, a new resin (3,3'-(1,4- phenylene) bis(1-(4-(4-hydroxybenzylidene) amino) phenyl) prop-2-en-1-one) to adsorb copper, cadmium and lead from wastewater. The new Schiff base was prepared on polyurethane foam diagnosed by FT-IR and 1H-NMR spectroscopic methods. The polymer has excellent sorption capacities due to the large specific surface area, chemical composition and the removal metals efficiency in varying proportions. For Cd2+, the efficiency removal was 100% in wastewater and the efficiency of removing Cu2+ was 100% in raw wastewater and primary sedimentation tank. The removal efficiency of Pb2+ was 86%, 64% and 79% 79% in raw sewage, primary and secondary sedimentation tank respectively.

Chitosan grafted tetracarboxylic functionalized magnetic nanoparticles for removal of Pb(II) from an aqueous environment

In this study, the chitosan-grafted tetracarboxylic functionalized magnetic nanoparticle (Fe3O4@TCA@CS) was synthesized via in situ co-precipitation process and amidation reaction to improve efficiency of adsorption process and obtain cost-effective adsorbents for removal of toxic Pb(II) metal from aqueous environment. The Fe3O4@TCA@CS nanocomposite was analyzed by FTIR, TEM-EDX, TGA, XRD, BET, and Zeta potential. The performance of Fe3O4@TCA@CS for Pb(II) ions adsorption was achieved as a function of pH, dose, contact time, initial Pb(II) concentration, and temperature. The influence of coexisting ions such as Na+, Ca2+, Mg2+, and Cd2+on removal efficiency of Pb(II) was also investigated. The results revealed that the coexisting ions had little influence on Pb(II) removal efficiency. The pseudo-first-order and Freundlich models were better to describe the adsorption of Pb(II) onto Fe3O4@TCA@CS and the maximum adsorption capacity of Pb(II) was 204.92 mg/g at pH:5.5; adsorbent dose: 0.015 g; and temperature: 298 K. Thermodynamic studies revealed that the Pb(II) adsorption onto Fe3O4@TCA@CS was an exothermic process. In conclusion, the study provides a new, simple, low-cost, and effective chitosan-based magnetic nanocomposite as a promising adsorbent with excellent adsorption capacity, magnetic separation, and reusability for Pb(II) removal from an aqueous environment.

Graphene oxide-based novel MOF nanohybrid for synergic removal of Pb (II) ions from aqueous solutions: Simulation and adsorption studies

Heavy metals represent a considerable threat, and the current study deals with synthesizing a novel MOF nanocomposite by intercalating graphene oxide (GO) and linker UiO-66-NDC. It was shown that UiO-66-NDC/GO had enhanced the removal efficiency of Pb (II) ions at pH 6. The adsorption kinetics data followed the PSO (Type 2) representing chemisorption. Adsorption data were also fitted with three different isotherms, namely Temkin, Freundlich, & Langmuir, and the Temkin model exhibited the best correlation (R2 0.99), representing the chemisorption nature of the adsorption process. The maximum adsorption capacity (qmax) of Pb (II) ions using Langmuir was found to be 254.45 mg/g (298 K). The Pb (II) adsorption process was confirmed to be exothermic and spontaneous as the thermodynamic parameters H° and G° were determined to have negative values. MOF nanocomposite also represents significant reusability for up to four regeneration cycles using 0.01 M HCl; for the next four, it works quite efficiently after regeneration. Meanwhile, the simulation findings confirm the superior dynamic stability (∼08 times) of the MOF nanocomposite as compared to the GO system. The removal of Pb (II) from simulated wastewater samples using a super nano-adsorbent using a MOF nanocomposite is described here for the first time.

Iron oxide-modified pervious concrete filter for lead removal from wastewater

The effects of partially adding iron-oxide-modified aggregate to OPC-based pervious concrete filter on the mechanical properties, heavy metal removal and leaching were investigated. Up to 10% of both coarse and fine aggregates were coated with iron oxide and filters (IOMA-C, coarse alone modified, IOMA-F fines alone modified and IOMA-CF) were prepared. Compressive strengths of the concrete improved while the permeability decreased by up to 13%. Simulated wastewater containing 15 ppm lead Pb (II) ions was passed through the control and IOMA-filters for 8 h under trickling water head. Iron-oxide-modified filter (IOMA-CF) showed maximum removal efficiency of 99.1% (87.3% for control). Desorption studies with 1M HNO 3 indicated that iron oxide complexed the Pb (II) ions more irreversibly, reducing the extent of their leaching. Batch studies were carried out at 1 g/L adsorbent loading (crushed control and IOMA-CF) with solutions containing 5 to 25 ppm Pb (II). Langmuir isotherm fit adsorption results on both the control and IOMA-CF systems while Temkin isotherm was the best fit for IOMA-CF, indicating the stronger, more irreversible chemisorption of Pb (II) on iron oxide. Theoretical adsorption capacities based on Langmuir isotherms for the control and IOMA-CF were 18.21 and 20.66 mg/g, respectively. Kinetics studies indicated that a pseudo second order kinetics model fit the results of all systems with a slightly slower rate of adsorption than the control system. Effects of pH and coexisting ions have been examined. These preliminary results indicate the potential of applying pervious concretes either as water filters or pretreatment units. • Pervious concrete filters with iron oxide-coated coarse and fine aggregates. • Pb(II) removal efficiencies from 93.6% to 99.1% from water. • Stronger chemisorption of Pb(II) on iron-oxide modified system — Temkin isotherm. • Pseudo-second-order kinetics, chemisorption is rate-limiting step. • Fast charge-based physisorption followed by slower chemisorption mechanism.

A graphene-based porous composite hydrogel for efficient heavy metal ions removal from wastewater

A graphene-enhanced supramolecular hydrogel containing poly(acrylic acid)(PAA) and poly(4-vinylpyridine) (P4VP) was fabricated for the wastewater remediation. In this work, P4VP brushes were grown from functionalized graphene oxide (GO) through surface-initiated atom transfer radical polymerization. Then, the P4VP-grafted GO (i.e., GO-g-P4VP) was integrated into PAA matrix to form GO-g-P4VP@PAA hydrogel as a highly efficient adsorbent for extraction of toxic metal ions from wastewater. Due to the introduction of GO-g-P4VP, the GO-g-P4VP@PAA composite hydrogel exhibited good compressive strength, and a special interconnected 3D porous network was formed in the hydrogel. The effect of pH, initial heavy metal ion concentration, contact time, and adsorbent dosage regarding the adsorption capacity and removal efficiency of Pb2+ and Cd2+ on the hydrogel was examined. Under appropriate conditions, the GO-g-P4VP@PAA hydrogel can achieve maximum adsorption capacities of 257.28 mg/g for Pb2+, 175.79 mg/g for Cd2+. The adsorption kinetics of Pb2+ and Cd2+ on the GO-g-P4VP@PAA hydrogel followed a pseudo-second order model and the adsorption isotherms were more consistent with the Langmuir isotherm model. In addition, the GO-g-P4VP@PAA hydrogel exhibited good reusability. After five cycles, the removal efficiency of both Pb2+ and Cd2+ still remained above 80 %. These results demonstrate the GO-g-P4VP@PAA hydrogel serves as a desirable adsorbent in removal of heavy metal cations from wastewater.

Sugarcane Bagasse and Orange Peels as Low-Cost Biosorbents for the Removal of Lead Ions from Contaminated Water Samples

The pollution of water by lead (Pb(II)) constitutes a substantial threat to the environment and subsequently to animals and humans. In this study, the efficacy of sugarcane bagasse (SCB) and orange peels (OPS) have been investigated as potential low-cost biosorbents, individually and in a homogeneous combination for the removal of Pb(II) from simulated and real water samples. Biosorbents were characterised using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) coupled to energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), powder X-ray diffraction (pXRD), a zeta potential analyser, and the Brunauer–Emmett–Teller (BET) method. Batch adsorption studies were explored under several experimental conditions to optimise the removal efficiency of Pb(II) ions from artificially contaminated aqueous solutions. The pH study revealed optimum removal efficiencies of Pb(II) at pH 7, for SCB and OPS. The optimum contact time for SCB and OPS individually and a homogenous mixture was 60, 120, and 120 min, respectively. The study also revealed that the optimum biosorbent dosage was 0.2, 0.17, and 0.2 g for SCB, OPS, and the homogenous combination of SCB and OPS (1:1). Optimum experimental conditions could achieve up to 100% removal efficiencies for 10 and 20 mg/L of Pb(II) using SCB and OPS, respectively. The potential of the homogenised combination of biosorbents demonstrated 100% removal efficiencies for 10 mg/L of Pb(II). The removal of 10 mg/L of Pb(II) in real water samples remained at 100% for biosorbents individually and the homogenised combination. The reusability performance of SCB, OPS, and the homogenised combination of SCB and OPS presented Pb(II) removal efficiencies above 70% for three adsorption–desorption cycles.

Application of Algal Nanotechnology for Leather Wastewater Treatment and Heavy Metal Removal Efficiency

Wastewater from tanneries may ruin agricultural fields by polluting them with trace metals. The synthesis of nanoparticles (NPs) from algal sources and their application could help in decreasing hazardous materials, for environmental safety. The potential of zinc oxide nanoparticles made from Oedogonium sp. was evaluated for removal of heavy metals from leather industrial wastewater. Synthesized algal nanoparticles (0 (control), 0.1, 0.5, and 1 mg) were applied to treat wastewater by using different concentrations of leather industrial effluents (0%, 5%, 10%, 15%, and 100%) for 15, 30, and 45 d. The wastewater collected was dark brown to black in color with very high pH (8.21), EC (23.08 μs/cm), and TDS, (11.54 mg/L), while the chloride content was 6750 mg/L. The values of biological oxygen demand (BOD) and chemical oxygen demand (COD) ranged between 420 mg/L and 1123 mg/L in the current study. Prior to the application of nanoparticles, Cr (310.1), Cd (210.5), and Pb (75.5 mg/L) contents were higher in the leather effluents. The removal efficiency of TDS, chlorides, Cr, Cd, and Pb was improved by 46.5%, 43.5%, 54%, 57.6%, and 59.3%, respectively, following treatment with 1 mg of nanoparticles after 45 d. Our results suggested that the green synthesis of ZnO nanoparticles is a useful and ecofriendly biotechnological tool for treating tannery effluents, before they are discharged into water bodies, thus making the soil environment clean.

Effects of the presence of phosphate buffer solution on removal efficiency of Pb and Zn in soil by solid phase microbial fuel cells.

Simple, effective and environment-friendly ways for remediating toxic metal pollution are necessary. In this study, the effect of different concentrations phosphate buffer solution (PBS) on removal efficiency of Pb and Zn in soil by solid phase microbial fuel cell (SMFC) was investigated. During 100days of operation, the SMFC with 150mM PBS generated the highest power density of 21.7 mW m-2 and the lowest internal resistance of 161 Ω. The addition of PBS can also increase soil conductivity and maintain a suitable pH for microbial activity. Furthermore, the removal rate of Pb and Zn in the SMFC with 150mM PBS can reach 14.7% and 22.3%, respectively. The microbial community analyses demonstrated that Anditalea as an exoelectrogen in alkaline-saline conditions was significantly enriched in the SMFC with 150mM PBS. This study provides an effective strategy for strengthening SMFC to remove toxic metals in soil.

Activated sludge process enabling highly efficient removal of heavy metal in wastewater.

Activated sludge process was a low-cost alternative method compared to the conventional physicochemical process for the treatment of heavy metal-containing wastewater. In the present study, the removal efficiency of Pb2+, Cu2+, and Ni2+ from wastewater by a sequencing batch reactor (SBR) activated sludge system was investigated, and the mechanism was revealed by static adsorption experiment of activated sludge. The results showed that the activated sludge in the SBR system was effective in removing Pb2+ and Cu2+ from wastewater at 10mg·L-1 initial concentration, with a removal efficiency of 83.1 ~ 90.0% for Pb2+ and 74.3 ~ 80.6% for Cu2+, respectively. However, the removal efficiency for Ni2+ was only 0 ~ 6.2%. Static adsorption experiments showed that the adsorption capacity of activated sludge for three heavy metals was shown as Pb2+ > Cu2+ > Ni2+. When the initial concentration was 20mg·L-1, the equilibrium adsorption capacity of activated sludge for Pb2+, Cu2+, and Ni2+ was 18.35mg·g-1, 17.06mg·g-1, and 8.37mg·g-1, respectively. The main adsorption mechanisms for Pb2+ and Cu2+ were ligand exchange, electrostatic adsorption, and surface organic complexation processes, but Ni2+ removal mechanism mainly included electrostatic adsorption and surface organic complexation processes, showing that Ni2+ removal was inhibited in the presence of Pb2+ and Cu2+. The physicochemical properties and microbial diversity of activated sludge were greatly affected by the heavy metals in the SBR system, and genus Rhodobacter was found to be dominant bacteria enabling resistance to heavy metal ions.