Removal Of Pb Research Articles

Zinc oxide functionalized MOF-5 for the adsorptive removal of Pb(II) metal ions and photocatalytic degradation of methylene blue dye in aqueous medium

Zinc oxide functionalized MOF-5 for the adsorptive removal of Pb(II) metal ions and photocatalytic degradation of methylene blue dye in aqueous medium

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.

Core-Shell Adsorbent Granules Fabricated from Sand/Graphene Oxide Nano-Composite for Adsorptive Removal of Pb (II)

Core-shell absorbent granules are produced by coating commercial sand gravels with graphite oxide (few-layer oxidized graphene sheets). Graphite oxide (GO) is synthesized chemically from vein graphite, a rare form of high purity natural graphite. Repeated coatings of graphite oxide on sand followed by low temperature (1200 C) thermal pyrolysis produce core-shell granules with a hierarchical structure in which sand gravels are covered by graphite oxide layers. The intention of this study is to assessment of feasibility of the mitigation of Pb (II) form the water by sand/graphene oxide nano-composite and study the dynamic behavior of the adsorption mechanism using the mathematical modeling. Individual materials and the resulting nanocomposite are characterized using a range of spectroscopic (FTIR, XRD, XPS) and microscopic (SEM/EDXA) techniques to elucidate the process of transforming individual materials into nanocomposite and to assess its suitability for removing Pb (II) from water. Stable sand/graphite oxide nanocomposites were obtained upon five times coating of GO on the sand surface and characterization shows that functionalized and a porous coating developed on the sand. The Pb (II) removal efficiency increases from high-acidic to neutral pH and decreases after basic (pH-8). The adsorption process takes 150 minutes to reach the equilibrium. After 150 minutes, the Pb (II) ion adsorption rate was constant. The maximum dosage of the nanocomposite needed to reach the equilibrium was 0.06g. Under the optimum conditions, 96.3% of Pb (II) removal efficiency was recorded from simulated Pb (II) containing water. According to the mathematical modeling, adsorption follows the Langmuir isotherm and fits well with the pseudo 2nd order kinetics model, indicating a homogeneous adsorption process via a monolayer process and Pb adsorbed onto the surface of the sand/GO nanocomposite by chemisorption. Sand/GO nanocomposite is an excellent candidate for removing Pb (II) from contaminated water.
 Keywords: Adsorption, Graphene oxide, Sand, Water treatment

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)

Porous Adsorbent Based on Kaolin and Nanomagnetic Cobalt Ferrite for Effective Removal of Pb(II) from Wastewater

Porous Adsorbent Based on Kaolin and Nanomagnetic Cobalt Ferrite for Effective Removal of Pb(II) from Wastewater

In-situ utilization of As(III) enhances selective recovery of heavy metals from acid mine drainage by hydroxyl-enriched Fe-Mn binary oxide

As(III), a common pollutant in acid mine drainage (AMD), can provide potential active sites for the adsorption of heavy metals on adsorbents. In this study, Pb(II), As(III), and Cu(II) were sequentially recovered from AMD using hydroxyl-enriched Fe-Mn binary oxide (O-FMO) via the in-situ utilization strategy of As(III). The results showed that the prepared O-FMO demonstrated better adsorption performance under acidic conditions than FMO. O-FMO exhibited an outstanding selectivity (＞99.6%) for the removal of Pb(II) and As(III) via the generation of insoluble As-Pb complex in AMD and the immobilized Pb and As could be subsequently separated using respective acid and alkaline solutions. Furthermore, the recovered O-FMO containing residual As could promote the selective removal of Cu(II) (Selectivity ＞98.4 %) from the treated AMD. Mechanism analysis revealed that the oxidized As(V) on the O-FMO played a dominant role in promoting metals adsorption via electrostatic interaction and complexation. Pb(II) can directly form a generally stable complex with H3AsO4 (As(V)) under acidic conditions, thereby replacing the Cu(II) and Cd(II) which only form acid-soluble complexes with H2AsO4-1 (As(V)). Besides, metal electronegativity affects the traits and the formation sequence of As-metal complexes. Hence, the recovery of metal(loid)s (purity > 98.4 %) from AMD following the order: Pb(II), As(III), and Cu(II) could be achieved by reutilizing O-FMO. This work offers a unique approach for AMD remediation by utilizing pollutants to treat pollution.

Sulfate-functionalized Fe-based MOF for removal of Pb(Ⅱ) and NO3- in industrial wastewater

In this work, a novel adsorption material (Fe-MOF) had been designed and synthesized by introducing sulfate ions into a framework with an environmentally friendly metal center (Fe(Ⅲ)). It can specifically remove Pb(Ⅱ) and NO3- ions in industrial wastewater. The structure and properties were characterized, and the existence of sulfate ions and the exposure of oxygen atoms were confirmed. The adsorption kinetics, isotherm and thermodynamics experiments had been carried out to study the adsorption properties. The experimental results showed that Fe-MOF had high selectivity for Pb(Ⅱ) ions, and its maximum adsorption capacity was as high as 504 mg/g. Remarkably, it could also adsorb NO3- ions, an equilibrium charge, by proton co-adsorption with maximum adsorption capacity of 304 mg/g. In addition, industrial wastewater was simulated, and the study showed that the presence of coexisting ions had little interference on the adsorption performance Cyclic experiments suggested Fe-MOF had an excellent adsorption-desorption circulation ability. The adsorption mechanism study confirmed that sulfate ions as the adsorption site improved its selectivity. These results provided a feasible method for the preparation of environmentally friendly MOFs adsorbents, and demonstrated the outstanding potential of sulfate functionalized MOFs in the treatment of industrial wastewater.

Effect and Mechanism of Bicarbonate Ion on Lead Absorption in Pontederia crassipes from Karst Water

Bicarbonate ions (HCO3−) are abundant in karst water with poor lead (Pb) utilization and biodegradation. This study aimed to investigate the mechanism of HCO3− on the Pb removal efficiency and uptake ability of Pontederia crassipes (a widespread hydrophyte in the karst area) from karst water. The Pb concentration, Pontederia crassipes morphology, and functional group were detected. As the HCO3− molarity in karst water increased (3, 4, and 5 mmol/L), the removal of Pb increased (85.31%, 93.28%, and 95.16%), whereas the bioconcentration amount of Pb decreased (573, 501, and 301 mg/kg), mainly due to the insoluble PbCO3 and Pb (OH)2. The Pb bioconcentration factor was the highest (15,564) at 4 mmol/L HCO3− due to the maximum strength of cation exchange and cell wall protein C=O. High HCO3− molarities changed the variety of positive ions of cation exchange (HCO3− ≤ 4 mmol/L: Na, K, and Mg; HCO3− > 4 mmol/L: Mg and K), and relieved the breaking of roots, stomatal closure, and vascular system shrinking. Moreover, high HCO3− molarities diminished the C≡C oxidation, enlarged the displacement of SO42− and C-O, and stimulated the methyl transfer reaction and the bonding between -CH3 and Pb.

Hagenia abyssinica-Biomediated Synthesis of a Magnetic Fe3O4/NiO Nanoadsorbent for Adsorption of Lead from Wastewater.

Magnetic nanocomposite adsorbents are cost-effective, environmentally friendly, easy to use, and highly efficient at removing metals from large volumes of wastewater in a short time by using an external magnetic field. In this study, an Fe3O4/NiO composite nanoadsorbent was prepared by varying the mass percent ratios of NiO (50, 40, 30, 20%), which are denoted Fe3O4/50%NiO, Fe3O4/40%NiO, Fe3O4/30%NiO, and Fe3O4/20%NiO, respectively, using Hagenia abyssinica plant extract as the template/capping agent and a simple mechanical grinding technique. The nanocomposites were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, nitrogen adsorption, and ζ-potential measurements. The adsorption performance of the nanoadsorbent was assessed for the removal of lead (Pb2+) ions from aqueous solutions. Among the composite adsorbents, Fe3O4/50%NiO demonstrated the best Pb(II) removal efficiency (96.65%) from aqueous solutions within 80 min at pH 8, at a 100 mg/L lead concentration and 0.09 g of adsorbent dose. However, with the same parameter, only 62.8% of Pb(II) was removed using Fe3O4 nanoparticles (NPs). The adsorptive performance indicated that the optimum amount of porous material (NiO) in the preparation of the Fe3O4/NiO composite nanoadsorbent, with the aid of H. abyssinica plant extract, enhances the removal of toxic heavy metals from aqueous solutions. Multiple isotherm and kinetic models were used to analyze the equilibrium data. Adsorption isotherm and kinetic studies were found to follow the Freundlich isotherm and pseudo-second-order kinetics, respectively.

Synthesis of Nano-silica Oxide for Heavy Metal Decontamination from Aqueous Solutions

In the current study, nano-silica oxide (nano-SiO2) was fabricated via the sol-gel technique. Then, the prepared nano-SiO2 was characterized using X-ray diffractometer (XRD), transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) specific surface area analysis. Furthermore, the fabricated nano-SiO2 was applied for the adsorption of lead Pb (II) and chromium Cr (VI) from aqueous solutions. Additionally, the influence of different operating factors such as contact time (0–180 min), initial pH (1–11), nano-SiO2 dose (0.1–8 g L−1), initial metal ion concentration (5–100 mg L−1), and the temperature (30–85 °C) was investigated. The nano-SiO2 doses of 0.5 and 1 g L−1 were selected as the optimal adsorbent dose for the removal of Pb (II) and Cr (VI), respectively. These doses achieved a removal efficiency of 82.3% and 78.5% for Pb (II) and Cr (VI), after 60 and 90 min, at initial pH values of 5 and 2, respectively, using 10 mg L−1 initial metal concentration, and at room temperature. Lastly, kinetic and equilibrium studies were competently fitted using the pseudo-second-order and Freundlich models, respectively. Adsorption thermodynamic studies designate the spontaneous and thermodynamic nature of the adsorption process. These results reveal the efficiency of the fabricated nano-SiO2 as an adsorbent for heavy metal removal from aqueous solutions.Graphical

Equilibrium, kinetic, and thermodynamic studies on the biosorption of lead by human metallothionein gene-cloned bacteria as a novel biosorbent.

Heavy metals are the main pollutants in water and are an important global problem that threatens human health and ecosystems. In recent years, there has been an increasing interest in the use of genetically modified bacteria as an eco-friendly method to solve heavy metal pollution problems. The goal of this study was to generate genetically modified Escherichia coli expressing human metallothioneins (hMT2A and hMT3) and to determine their tolerance, bioaccumulation, and biosorption capacity to lead (Pb2+ ). Recombinant MT2A and MT3 strains expressing MT were successfully generated. Minimum inhibition concentrations (MIC) of Pb for MT2A and MT3 were found to be 1750 and 2000 mg L-1 , respectively. Pb2+ resistance and bioaccumulation capacity of MT3 were higher than MT2A. Therefore, only MT3 biosorbent was used in Pb2+ biosorption, and its efficiency was examined by performing experiments in a batch system. Pb2+ biosorption by MT3 was evaluated in terms of isotherms, kinetics, and thermodynamics. The results showed that Pb biosorption fits to the Langmuir isotherm model and the pseudo-first-order kinetic model, and the reaction is exothermic. The maximum Pb2+ capacity of the biosorbent was 50 mg Pb2+ g-1 . The potential of MT3 in Pb biosorption was characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM) analyses. The desorption study showed that the sorbent had up to 74% recovery and could be effectively used four times. These findings imply that this biosorbent can be applied as a promising, precise, and effective means of removing Pb2+ from contaminated waters. PRACTITIONER POINTS: In this study, the tolerance levels, bioaccumulation, and biosorption capacities of Pb in aqueous solutions were determined for the first time in recombinant MT2A and MT3 strains in which human MT2A and MT3 genes were cloned. The biosorbent of MT3, which was determined to be more effective in Pb bioaccumulation, was synthesized and used in Pb biosorption. The Pb biosorption mechanism of MT3 biosorbent was identified using isotherm modeling, kinetic modeling, and thermodynamic studies. The maximum Pb removal percentage capacity of the biosorbent was 90%, whereas the maximum biosorption capacity was up to 50 mg Pb2+ g-1 . These results indicated that MT3 biosorbent has a higher Pb biosorption capacity than existing recombinant biosorbents. MT3 biosorbent can be used as a promising and effective biosorbent for removing Pb from wastewater.

Green and Efficient Removal of Toxic Lead and Chromiumfrom Synthetic Leather Tannery Wastewater using Electrocoagulation

Most of leather tanneries in Pakistan dispose of tannery effluent untreated in sewage lines causing serious harmful environmental impact. Some of tanneries use conventional activated sludge process releasing large quantity of sludge and not effective for treating heavy metal in leather tanneries. The manuscript deals with implementation of electrocoagulation technology for removal of Cr and Pb from Leather tannery effluent, investigation of operating parameters current density, treatment time and pH on removal efficiency. Electrodes was made of Iron having dimension 9.5 cm x 0.6 cm x 0.4 cm and affective surface area of electrode was 76 cm<sup>2</sup>. After conducting different experiments at various operating conditions, pH 3.5 and current density 18.8 milliamp/cm2 was found to be optimized condition for treating 1 liter of synthetic leather tannery effluent. The maximum removal efficiency of chromium and lead was obtained 87.8 % and 62.7 % respectively at pH 3.5 and current density of 18.8 milliamp/cm<sup>2</sup>. The EDX analysis of sludge shows presence of chromium, lead and iron element in sludge and FTIR analysis shows the presence of hydroxyl functional group in sludge, it is strong evidence of iron polymer complexes formation with chromium and lead during treatment of synthetic leather tannery wastewater. Both of these analysis show strong evidence of effective electrocoagulation process. It was proved that electrocoagulation can effectively treat synthetic leather tannery effluent. The SEM analysis shows production of coagulant on surface of electrode.

Simultaneous removal of lead, cadmium, and norfloxacin by Calcite/PMS system: Performance and mechanisms

This work investigated the performance and mechanisms of calcite activating peroxymonosulfate (PMS) for the simultaneous elimination of lead (Pb(II)), cadmium (Cd(II)), and norfloxacin (NOR). At an initial pH = 7, 1.0 g/L calcite, and 0.5 mM PMS, the removal of Pb(II), Cd(II), and NOR was 97.5%, 96.0%, and 98.1%, respectively. The results of EPR, quenching, and chemical probe quantification experiments revealed that singlet oxygen (1O2) derived from calcite activating PMS dominated NOR degradation. Meanwhile, surface complexation and carbonate precipitation were identified as the main mechanisms in the removal of Pb(II) and Cd(II) by ATR-FTIR and different ionic strength experiments, respectively. Kinetic analysis and XPS results indicated that the solid phase Pb(IV) generated through surface complexed Pb(II) oxidized by PMS facilitated the NOR degradation. The NOR degradation pathway along with biological toxicity assessment was also presented through HPLC-MS and ECOSAR software. This study provides the prospects of using natural carbonate minerals to activate PMS for treating the combined contamination of antibiotics and heavy metal ions, and also provides a new understanding of the removal of organic substances in the presence of heavy metal ions.

Performance optimization for Pb(II) -containing wastewater treatment in constructed wetland-microbial fuel cell triggered by biomass dosage and Pb(II) level.

Three identical sets of constructed wetland-microbial fuel cells (CW-MFCs) fabricated with biomass carbon source addition were constructed and underwent the short- and long-term experiments. For this, the efficacy of biomass dosage and Pb(II) concentration towards Pb(II) removal and concurrent bioelectricity production of CW-MFCs were systematically explored. From the perspective of integrated capabilities and economic benefits, the solid biomass carbon sources equivalent to 500mg/L COD was regarded as the optimal dosage, and the corresponding device was labeled as CW-MFC-2. For the short-term experiment, the closed-circuit CW-MFC-2 produced maximum output voltages and power densities in a range of 386-657mV and 1.55 × 103-6.31 × 103 mW/m2 with the increasing Pb(II) level, respectively. Also, Pb(II) removal up to 94.4-99.6% was obtained in CW-MFC-2. With respect to long-term experiment, Pb(II) removal, the maximum output voltage, and power density of CW-MFC-2 ranged from 98.7 to 99.2%, 322 to 387mV, and 3.28 × 102 to 2.26 × 103 mW/m2 upon 200mg/L Pb(II) level, respectively. The migration results confirmed the potential of substrate and biomass for Pb(II) adsorption and fixation. For the cathode, Pb(II) was fixed and removed via binding to O. This study enlarges our knowledge of effective modulation of CW-MFCs for the treatment of high-level Pb(II)-containing wastewater and bioelectricity generation via adopting desirable biomass dosage.

Spectra metrology for interaction of heavy metals with extracellular polymeric substances (EPS) of Pseudomonas aeruginosa OMCS-1 reveals static quenching and complexation dynamics of EPS with heavy metals

The adsorption behavior and interaction mechanisms of extracellular polymeric substances (EPS) of Pseudomonas aeruginosa OMCS-1 towards chromium (Cr), lead (Pb), and cadmium (Cd) were investigated. EPS-covered (EPS-C) cells exhibited significantly higher (p < 0.0001; two-way ANOVA) removal of Cr (85.58 ± 0.39%), Pb (81.98 ± 1.02%), and Cd (73.88 ± 1%) than EPS-removed (EPS-R) cells. Interactions between EPS-heavy metals were spontaneous (ΔG<0). EPS-Cr(VI) and EPS-Pb(II) binding were exothermic (ΔH<0), while EPS-Cd(II) binding was endothermic (ΔH>0) process. EPS bonded to Pb(II) via inner-sphere complexation by displacement of surrounding water molecules, while EPS-Cr(VI) and EPS-Cd(II) binding occurred through outer-sphere complexation via electrostatic interactions. Increased zeta potential of Cr (29.75%), Pb (41.46%), and Cd (46.83%) treated EPS and unchanged crystallinity (CIXRD=0.13), inferred EPS-metal binding via both electrostatic interactions and complexation mechanism. EPS-metal interaction was predominantly promoted through hydroxyl, amide, carboxyl, and phosphate groups. Metal adsorption deviated EPS protein secondary structures. Strong static quenching mechanism between tryptophan protein-like substances in EPS and heavy metals was evidenced. EPS sequestered heavy metals via complexation with C-O, C-OH, CO/O-C-O, and NH/NH2 groups and ion exchange with –COOH group. This study unveils the fate of Cr, Pb, and Cd on EPS surface and provides insight into the interactions among EPS and metal ions for metal sequestration.

Competitive heavy metal adsorption on pinecone shells: Mathematical modelling of fixed-bed column and surface interaction insights

Pinecone shells are assessed as a cost-effective biosorbent for the removal of metal ions Pb(II), Cu(II), Cd(II), Ni(II), and Cr(VI) in a fixed-bed column. Influent concentration, bed height, and flowrate are studied to improve efficiency. The breakthrough data is well fitted by the Sips adsorption model, suggesting a surface complexation mechanism, with maximum adsorption capacities of 11.1 mg/g for Cu(II) and 66 mg/g for Pb(II).In multimetal solutions, the uptake sequence at breakthrough and saturation is Pb(II) > Cu(II) > Cd(II). Characterization via FTIR and XRD reveals carboxyl and hydroxyl functional groups interacting with metal ions. Ca(II) does not compete with Pb(II), Cu(II), and Cd(II) adsorption, highlighting the ability of pinecone to adsorb heavy metals via surface complexation. Its application in the treatment of industrial effluents containing Cu(II), Ni(II), and Cr(VI) is explored.The study investigates bed media regeneration via eluting adsorbed metal ions with hydrochloric acid solutions. The potential of pinecone shells as an efficient biosorbent for removing toxic metal ions from industrial wastewater is emphasized. These findings enhance our understanding of the adsorption mechanism and underscore the fixed-bed column system's applicability in real-world scenarios, addressing environmental concerns related to heavy metal contamination of industrial effluents.

Modulated assembly of multi-variate MOFs: The role of functional defects in high capacity Hg(II) and Pb(II) removal and asymmetric catalysis

Mixed modulator is a novel approach for the one-pot insertion of various characteristics in the context of Metal-Organic Frameworks. In this work, a series of novel chiral defective MOFs (Zn.Mands) were synthesized using various ratios of terephthalic acid and L-Mandelic acid (L-Mand) as linker and modulator, respectively. The hydrogen-bond donation, bearing the Brønsted acid site as well as chirality induction are regarded as the main reasons for choosing L-mandelic acid. In the next step, we also applied a mixed-modulator approach, to prepare Zn.Mand family as multi-variate MOFs (MTV-MOFs) with broad applicability as well as chirality. We succeeded in showing, that the using of propionic acid, mercaptopropionic acid, or lauric acid in addition to L-mandelic acid, afforded a series of efficient frameworks Zn.Mand (PRA, MPA, LA) with high hydrophobicity, hierarchical porosity, hydrogen-bond donating along with chirality. Although utilization of a single chiral modulator (L-Mand) led to the appreciable result in promoting asymmetric ring-opening reactions with high enantiomeric excess, and also in the adsorption of heavy metal, mixed-modulators approach can boost these performances. The samples were synthesized with mixed modulators, especially Zn.Mand (MPA) showed excellent performance in Pb (II) and Hg (II) adsorption (qm = 1050 mg g−1, 900 mg g−1, respectively), owing to the simultaneous presence of thiol and hydroxyl functional groups. On the other hand, Lewis acid sites (defect centers), besides the high density of Brønsted acid sites (−SH and −OH), caused Zn.Mand (MPA) promotes the asymmetric ring-opening reactions (98 % conversion, 99 % ee) without significant loss of activity, to the fifth step of consecutive cycles. In similar conditions (12 h and 60 °C), this result is higher than Zn.Mand with 48 % conversion, revealing the significance of the mixed-modulator approach. This study provides insights into the benefits of modulator-based tuning of functionality in addition to exploring an avenue to broaden the industrial application scope of MOF. Furthermore, by employing this easy-to-operate, low-cost, and efficient synthesis route, multifunctional MOFs are produced which can't be achieved through conventional approaches.

Efficient and cost-effective adsorbent brick sand nanoparticles used for removal of heavy metals

ABSTRACT We are introducing cost effective, easily available brick sand nano-particles (BSNP) (44.208 nm) as an adsorbent in batch process for removal of heavy toxic metals such as Pb, Cd, and Cr from aqueous solution. We used two types of adsorbents, one is acid treated BSNP and other one is untreated BSNP, and investigated adsorbent properties with function of contact time, temperature, and pH. The efficiency or performance of adsorbent was characterized by AAS for percentage of removal from solution, EDS for elemental analysis to confirm the metals adsorption. The Langmuir, Freundlich, Temkin, Hill De Boer, Elovich, and Redlich-Peterson adsorption isotherms were studies to find out the quality of the adsorbent. At 5.68 to 7.6 pH, the maximum removal percentages of Pb, Cd, and Cr were 97% from the aqueous solution. The temperatures at 40℃ to 60℃, the Pb, Cd, and Cr experiments were carried out at their highest possible percentages (98%). The reaction process was pseudo-second order model and several thermodynamic factors, including Intraparticle diffusion, Elovich kinetic model, Boyd kinetic model, activation energy, Gibbs free energy, enthalpy change, and entropy change ensured the adsorbent efficiency of brick sand nanoparticles. The results of present research indicated that Brick Sand Nano-Particles (BSNP) may play a vital role as a cost-effective, efficient, and easily available adsorbent for the removal of Pb, Cd, and Cr from wastewater.

Effect of ablation time for loading amounts of magnetic nanoparticles on CNTs for removal of Pb (II) ions from aqueous solution

Effect of ablation time for loading amounts of magnetic nanoparticles on CNTs for removal of Pb (II) ions from aqueous solution

Dual-use of sodium alginate to prepare sodium algenate -derived carbon dots sodium algenate hydrogel composite for Pb2+ removal

The effective mitigation of the environmental impact of heavy metal remains a significant scientific challenge. In this study, a novel and environmentally friendly approach has been proposed to fabricate three-dimensional (3D) functional composite materials for Pb(II) removal. The easy-to-recycle spherical adsorbent is prepared by the dual utilization of sodium alginate (SA) as a bio-source precursor for the synthesis of carbon dots (CDs) and as a natural framework for the formation of SA hydrogel. The abundant surface-active groups on the SA hydrogel not only provide additional adsorption sites for the aggregation of heavy metal ions but can also be readily cross-linked with CDs without chemical additives, and thereby offering a 3D porous structure for chelating metal ions. The resulting HL-5CDs adsorbent demonstrates an impressive adsorption capacity of 305.21 mg·g−1 for Pb(II). The adsorption mechanism involves both chemical reaction and diffusion, leveraging the porous structure and rich oxygen groups of the material. Notably, a pot experiment revealed that the as-prepared HL-5CDs could inhibit the bioavailability of Pb(II). This study introduces a green and straightforward method for creating high-performance adsorbents, showcasing potential applications in energy, cleaning, and the remediation of wastewater pollution.