Heavy Metal Adsorption Capacity Research Articles

Study on the solidification performance and mechanism of heavy metals by sludge/biomass ash ceramsites, biochar and biomass ash.

Industrial by-products are stored in large quantities in the open, leading to wasted resources and environmental pollution, and the natural environment is similarly faced with phosphate depletion and serious water and soil pollution. This study uses these by-products to produce a new sludge/biomass ash ceramsite that will be used to adsorb nitrogen and phosphorus from wastewater, and solidify heavy metals in the soil while releasing Olsen P. The sludge/biomass ash ceramsites are made using sewage sludge and biomass ash in a certain ratio calcined at high temperatures and modified for the adsorption of nitrogen and phosphorus from wastewater. Sludge/biomass ash ceramsites before and after phosphorus adsorption, biochar and biomass ash were compared to analyze their heavy metal adsorption capacity and potential as phosphate fertilizer. After phosphorus adsorption, the sludge/biomass ash ceramsites released effective phosphorus steadily and rapidly in the soil, with a greater initial release than biochar and biomass ash, and the ceramsites were in a granular form that could be easily recycled. Biochar and biomass residue, due to their surface functional groups, are better at solidifying heavy metals than sludge/biomass ash ceramsites. Biochar, biomass ash and sludge/biomass ash ceramsites significantly reduced the concentrations of Cd, Cu, Pb and Zn in the soil. Correlation analysis demonstrated that there was a synergistic relationship between the increase in soil Olsen P content and the change in pH, with the increase in soil Olsen P content and the increase in pH contributing to heavy metal solidification.

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.

Isolation and Influence of Carbon Source on the Production of Extracellular Polymeric Substance by Bacteria for the Bioremediation of Heavy Metals in Santo Amaro City

The city of Santo Amaro (Bahia, Brazil) gained visibility among the scientific community due to the contamination of the Subaé River by lead and cadmium from the PLUMBUM Mineração e Metalurgia Ltda industry, on the banks of the river in 1956, which produced lead ingots The present work aimed to investigate the adsorption capacity of heavy metals (Pb and Cd) of EPS produced by bacterial species from the Subaé River, for possible future application of these biopolymers in bioremediation processes in areas impacted by the aforementioned heavy metals. Subaé river water was collected for physical-chemical analysis and bacterial isolation. It was verified that all isolated bacteria produced an expressive amount of Exopolysaccharide (EPS). Thus, the optimization of this production in different sugars (sucrose, glucose, and mannitol) and in three different pHs: 5.5; 6.5, and 7.5. All bacteria produced EPS in large quantities and the best sugar was sucrose at pH 7.5. In order to use the EPS for the bioremediation area, the adsorption test of lead and cadmium was carried out by the isolated EPS. 0.5 g of the EPS was dissolved in 50 ml of deionized water, then the solutions of metals, lead acetate, and cadmium sulfate (procedure performed separately) were incubated at 28 °C for 16 h after that period, and were centrifuged. Samples were filtered to separate the insoluble EPS and the filtrates obtained were used in the quantification of the metals by atomic absorption (FAAS- Flame Atomic Absorption Spectrometry). Bacillus spp., Bacillus cereus, Staphylococcus spp., and Serratiamarcescens, all showed tolerance to the tested metals, due to the efficiency in the adsorption capacity of the EPS, and it was possible to distinguish seven genera, Klebsiella pneumonia, Pseudomonas aeruginosa, Lysinibacillus spp. to be used in the bioremediation of environments contaminated with heavy metals.

Textile waste valorization as potential activated carbon precursor for the removal of water contaminants: Commentary

Textile waste has become a global concern as its generation is increasing at an alarming rate. Various ways to manage and reduce textile waste are currently being sought, including reutilization and conversion into value-added products, to diversify its usage in an effort to minimize its environmental impact. Recent trends have shown the potential of textile waste as low-cost adsorbent for wastewater treatment applications. This paper aims to highlight the activation methods to convert textile waste into activated carbon and discuss its textural characteristics and performance in water contaminants removal. Data from literature showed promising high adsorption capacities of heavy metals, dyes, and pharmaceuticals by textile waste-derived activated carbons. Overall, the valorization of textile waste into activated carbon is generally feasible. Also, the superior surface chemistry and textural properties are imperative towards the exceptional performance of textile waste activated carbon in wastewater treatment applications.

Mathematical Models for Adsorption Capacity and Percent Removal of Heavy Metals from Water Using Stat-Ease 360

Heavy metal removal using adsorbent materials like watermelon rind, as investigated herein, will ensure a safe drinking water for consumption. For the first time, mathematical models taking A = adsorbent dosage, B = contact time and C = initial concentration as input variables were developed using Stat-Ease 360 design of experiment (DOE) tool for adsorption capacity (R1) and percent removal of heavy metals including, arsenic, cadmium, chromium, copper and lead (R2) in water, as two sole output variables. The models generated based on existing experimental observations (A, B, C) can be used to predict the responses or outputs of the adsorption process, especially looking at their respective satisfactory statistical performance parameters obtained. Several 3D surface and contour plots reveal the optimal factor combination for peak response performance for a particular metallic contaminant in the water. Optimal values for arsenic removal are 0.1g A, 120 min B, 3.12 mg/g R1 and 100% R2. Those of other metals present are as follows: 0.1g A, 60 min B, 0.17 mg/L C, 144.75 mg/g R1 and 85.78% R2 for cadmium; 0.1-1.2g A, 0<B≤120 min, 0.028 mg/L C, 215 mg/g R1 and 85.53% R2 for chromium; 0.1-1.2g A, 0<B≤120 min, 0.041 mg/L C, 275 mg/g R1 and 80% R2 for copper and; 0.1-1.2g A, 0<B≤120 min, 0.029 mg/L C, 205 mg/g R1 and 83.42% R2 for lead. This study falls short of many heavy metals such as zinc, nickel, cobalt, antimony, iron and mercury removal used to test the effect of other factors like pH, presence of co-existing ions, temperature and sorbent particle size for their adsorption performance.

Chitosan-based adsorptive membrane modified by carboxymethyl cellulose for heavy metal ion adsorption: Experimental and density functional theory investigations

Low adsorption capacity and weak mechanical stability are the main drawbacks of chitosan (CS)-based adsorptive membranes for heavy metal ion removal. Polyvinyl alcohol (PVA) has been used to improve the mechanical stability of CS membranes, but adsorption capacity is disregarded. In the current study, the surface of the chitosan/polyvinyl alcohol (CP) membrane was modified using carboxymethyl cellulose (CMC) to increase its heavy metal ion adsorption capacity. Experimental and density functional theory (DFT) calculations were used to evaluate the heavy metal ion (As3+ and Cr3+) adsorption capabilities of CP and carboxymethyl cellulose-functionalized CP (CMC-CP) membranes. The batch adsorption process presented a higher heavy metal adsorption capacity of the CMC-CP membrane (As3+/CMC-CP = 234.78 mg/g and Cr3+/CMC-CP = 230.12 mg/g) compared to the CP membrane (As3+/CP = 89.02 mg/g and Cr3+/CP = 75.61 mg/g). The heavy metal/CMC-CP complexes confirmed higher adsorption energies (As3+/CMC-CP = −23.62 kcal/mol and Cr3+/CMC-CP = −23.21 kcal/mol) than the heavy metal/CP complexes (As3+/CP = −3.47 kcal/mol and Cr3+/CP = −2.92 kcal/mol). The electronic band structure was higher for CMC-CP (5.42 eV) compared to CP (4.43 eV). Experimental and theoretical findings were close, implying that the CMC-CP membrane has superior heavy metal adsorption capability than the CP membrane.

Polythiophene incorporated polysulfone blend membranes for effective removal of zinc and iron from electroplating effluent: Experimental studies and performance modelling

Polythiophene (pTh) was doped in a polysulfone (Psf) matrix to form ultrafiltration (UF) grade blend membranes. The membranes showed negative surface potential at neutral pH condition (zeta potential: −18 mV for membrane M-0.5 at pH 7) along with good adsorption capacities for various heavy metals. The optimum membrane M-0.5 (with 0.5 wt% pTh concentration) had the highest heavy metal selectivity (adsorption capacities of 81, 64.4, 59 and 51 mg/g for lead, iron, zinc and copper ions, respectively) with a permeability of 4.92 × 10-11m/Pa.s. Furthermore, the potential of the blend M-0.5 membrane was investigated for the reduction of Zn(II) and Fe(II) from an electroplating effluent using a two-stage UF to reduce metal ion concentration below the dischargeable limit. The membrane M-0.5 had a breakthrough time of 16 h for the synthetic solution and 10 h for the 2ndstage of industrial wastewater. A two-dimensional multicomponent transient convective-adsorption model was utilized to predict the membrane performance.

Study on the effects of new developed biochar and sludge composite materials on copper and lead contaminated soil and its remediation mechanism

In this study, composite repair material was obtained by composting and fermentation of straw biochar and sludge according to the mass ratio of 1:4. The remediation effect of its composite remediation materials on heavy metals copper (Cu) and lead (Pb) in soil was investigated. The characterization results of the composite remediation material showed that the material had rich pore structure, high specific surface area and rich functional groups such as hydroxyl, carbonyl and carboxyl groups, and had high adsorption capacity for heavy metals in contaminated soil. The passivation effect of Cu and Pb in contaminated soil was investigated under different application amount (3%, 5%) and passivation time (15d, 60d). The changes of Cu and Pb content, availability and morphology distribution in the soil before and after the addition of remediation materials were analyzed. The results showed that the passivation effect of Cu and Pb in soil was significantly enhanced with increasing passivation time and application amount. In conclusion, the addition of remediation materials effectively reduced the content and effectiveness of heavy metals in the soil and promoted the change of Cu and Pb morphology in the heavy metal-contaminated soil, thus realizing the remediation of the heavy metal-contaminated soil.

Preparation of basic magnesium carbonate nanosheets modified pumice and its adsorption of heavy metals.

Heavy metal pollution in wastewater poses a grave danger to the environment and the human body. Pumice is a mineral with abundant reserves and low prices, and its prospect of heavy metal adsorbent is very broad. In this work, we modified pumice with basic magnesium carbonate nanosheets by a convenient hydrothermal synthesis. The adsorption capacity of heavy metals is greatly improved. The effects of different pH and adsorption dosages are investigated. All the optimum pH values for Cu2+, Pb2+, and Cd2+ are 5. The adsorption of three kinds of ions conforms to the quasi-second-order adsorption kinetics model. The theoretical adsorption capacities of Cu2+, Pb2+, and Cd2+, which are calculated by the Langmuir model, are 235.29mg/L, 595.24mg/L, and 370.34mg/L, respectively. The adsorption of Cu2+ and Cd2+ fit the Langmuir model better. The Freundlich model is fitted well with the adsorption of Pb2+. In the experiment simulating real wastewater, the adsorption capacity of heavy metals is not affected. It also shows good reusability in three regeneration cycles. And Mg5(CO3)4(OH)2·4H2O@pumice adsorption column showed the good removal efficiency of three heavy metals at different concentrations and different spatial velocities in the column experiment. Thus, it is believed that the Mg5(CO3)4(OH)2·4H2O@pumice is a promising adsorbent for the efficient removal of heavy metals.

Synthesis of Na-A zeolite loaded bentonite and its application for removal of Cu(II) from aqueous solutions

Zeolites are highly valued as adsorbent materials for the removal of heavy metals due to their exceptional adsorption properties, ease of synthesis, stability, and high adsorption capacity. Bentonite is an abundant and cheap adsorption material, and its aluminosilicate layers have large spacing to accommodate massive hydrated ions or macromolecular organics. In this study, bentonite is designed as the carrier material and Na-A zeolite is synthesized between its aluminosilicate layers, in order to obtain a low-cost modified bentonite with high heavy metal adsorption capacity. Results demonstrate that Na-A zeolite could be satisfactorily synthesized between bentonite aluminosilicate layers at a low synthesis temperature (80 °C) and short time (10 h). The pseudo-second-order kinetic model is more appropriate for characterizing the Cu(II) adsorption process on Na-A zeolite loaded bentonite, and the Freundlich isotherm is favorable for fitting the experimental data of Cu(II) adsorption. The Cu(II) adsorption mechanism by this composite material involves both ion exchange and chemical bonding, associated with its lamellar and cubic combined microstructure.

Use of biochar as a low-cost adsorbent for removal of heavy metals from water and wastewater: A review

In recent years, the removal of heavy metals from water and wastewater systems remains a challenging issue globally. Adsorption technology is widely used for the removal of heavy metals from aquatic systems due to several advantages including its simple operation, low cost and high efficiency. Biochar, which is an environmental benign and low-cost adsorbent, is increasingly used for remediation of heavy metal pollution in aquatic systems. This review critically analyzes recent developments on the biochar-based adsorptive removal of heavy metals from water and wastewater. Biochar is effective for the removal of several toxic metals (As, Cr and Mn) from groundwater and drinking water. Biochar also shows promising performance for the removal of various heavy metals (Cr, Pb, Cu, Cd and Zn) from wastewater. The heavy metal adsorption capacity of the biochar largely depends on the water/wastewater chemistry (pH, competing ions and initial concentrations of adsorbates), contact time between adsorbates and the adsorbent, adsorbent dose and environmental parameters (temperature). The adsorption isotherms and kinetics can be well explained by the Langmuir and pseudo-second order models, respectively. The key mechanisms which drive the heavy metal adsorption onto biochar include precipitation and ion exchange. Biochar-based adsorptive decontamination of heavy metal pollution is sustainable due to low environmental impacts, low energy consumption and low-costs. The key knowledge gaps and future research directions for improvement of biochar-based sorption capacities are highlighted. This review would help for the development of effective biochar-based adsorption technology for the removal of heavy metals from aquatic environments.

Synthesis and Characterization of Terpolymer Adsorbents Using Photopolymerization: Investigation of Heavy Metal Adsorption Capacity

In this study, poly(allylphenol-co-methylmethacrylate-co-vinyl imidazole) (PAMV) terpolymer adsorbents were synthesized using the photopolymerization method with 1-vinyl imidazole, methyl methacrylate, and 2-allylphenol monomers. Structural and surface analyzes of PAMV polymers obtained using different mole ratios 1H-Nuclear Magnetic Resonance, Fourier-Transform Infrared Spectroscopy, X-Ray Photoelectron Spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-Ray and thermal characterization were performed using Thermogravimetry methods. Inductively Coupled Plasma Mass Spectrometry was used for adsorption studies. Optimization studies were carried out at different pH values. According to the results obtained, the pH range in which adsorbents operate at maximum efficiency is between 6-10. Although many different metals have been studied, the holding capacity of the obtained polymeric adsorbent on cadmium, chromium and mercury metal ions is quite remarkable.

Study on Heavy Metal Adsorption Capacity According to Modification Conditions with Ca-Zeolite

Study on Heavy Metal Adsorption Capacity According to Modification Conditions with Ca-Zeolite

Study on Heavy Metal Adsorption Capacity According to Modification Conditions with K-Zeolite

Study on Heavy Metal Adsorption Capacity According to Modification Conditions with K-Zeolite

Revolutionizing biochar synthesis for enhanced heavy metal adsorption: Harnessing machine learning and Bayesian optimization

Biochar is widely recognized as an effective approach for mitigating heavy metal pollution. However, the utilization of machine learning models to guide biochar preparation and enhance its adsorption performance poses challenges. This study proposed a biochar design strategy guided by the Bayesian optimization algorithm. The strategy involves automated hyperparameter optimization for machine learning model training and exploration of unexplored biochar preparation conditions using the Bayesian algorithm. By leveraging Bayesian algorithms for hyperparameter search, we successfully crafted random forest models, support vector regression models, and back propagation models. In comparison to the previously reported models, these models demonstrated outstanding performance, with the random forest model in particular showcasing superior results (R2 = 0.998; RMSE = 0.027). Using a Bayesian algorithm, it was found that more than 80% of the feature combinations would exceed the upper limit of heavy metal adsorption. Our model revealed that biochar with a mesoporous structure, produced at a pyrolysis temperature of 420 °C, exhibited enhanced heavy metal adsorption capacity. This study presented a novel approach for the rapid development of machine learning models using Bayesian optimization and employed inverse reasoning to guide biochar preparation and enhance adsorption performance.

Aging behavior of microplastics accelerated by mechanical fragmentation: alteration of intrinsic and extrinsic properties.

Microplastics (MPs) inevitably undergo multiple aging processes during their life cycle in the environment. However, the information regarding the mechanical fragmentation behavior of MPs remained unclear, including the changes in the intrinsic properties of aged MPs, the measurement of aging degree, the underlying mechanism, and the interaction with heavy metals. Here, MPs (PS, PP, PET) were aged by crushing (-CR) and ball-milling (-BM) to simulate mild and severe mechanical fragmentation, respectively. Our results indicated that mechanical fragmentation significantly affected the morphology of MPs. The aging degree of MP-BM was deeper compared to MP-CR owing to smaller particle size, larger specific surface area, poorer heat resistance, better hydrophilicity, and richer oxygen-containing functional groups. The carbonyl index (CI) and O/C ratio were used to measure the aging degree of the two mechanical aging treatments. Besides, the mechanism was proposed and the discrepancy between the two treatments was elaborated from three aspects including the excitation energy source, reaction interface, and reaction dynamics. Furthermore, the extrinsic properties of MPs altered with the increase of aging degree; specifically, the adsorption capacities of heavy metals were enhanced. Meanwhile, it was unveiled that the CI value and O/C ratio played a vital role in estimating the adsorption ability of heavy metals. The findings not only reveal the mechanical fragmentation behavior of MPs but also provide new insights into the assessment of the potential risks of the aged MPs via chemical indexes.

Response of Heavy Metals to Microseism in Coal Mining Subsidence Water of Huainan, China

Coal mining causes surface subsidence, and the accumulated water body is constantly affected by the mining microseism in this process. Understanding the relationship between the subsided water quality and microseism plays a special role in assessing the environmental impact of mining activities. Based on sampling and monitoring, analyzing, and evaluating the Pansan subsided water area of Huainan, the influence of microseism activity on heavy metal elements in subsided water was verified. We found that the microseism effects decreased the contents of Zn, Pb, and Cu in the subsided water by 43.76%, 35.88%, and 28.83%, respectively, and Cd was not detected. The mechanism of heavy metal evolution in the water–sediment system under microseism factors was further explored by simulating experiments with similar materials. The results showed that the mining microseism increases the heavy metal adsorption capacity of suspended solids, and the dissolved heavy metals in water were transformed into suspended heavy metals. The heavy metals of subsided water eventually accumulate in the sediment, and the purpose of controlling heavy metal pollution can be achieved through regular cleaning of the bottom sediment.

Protein/Polysaccharide Composite toward Multi-in-One Toxin Removal in Blood with Self-Anticoagulation and Biocompatibility.

Biocompatible adsorbents play an essential role in hemoperfusion. Nevertheless, there are no hemoperfusion adsorbents that can simultaneously remove small and medium toxins, including bilirubin, urea, phosphor, heavy metals, and antibiotics. This bottleneck significantly impedes the miniaturization and portability of hemoperfusion materials and devices. Herein, a biocompatible protein-polysaccharide complex is reported that exhibits "multi-in-one" removal efficacy for liver and kidney metabolism wastes, toxic metal ions, and antibiotics. Through electrostatic interactions and polysaccharide-mediated coacervation, adsorbents can be prepared by simply mixing lysozyme (LZ) and sodium alginate (SA) together in seconds. The LZ/SA absorbent presented high adsorption capacities for bilirubin, urea, and Hg2+ of up to 468, 331, and 497mgg-1 , respectively, and the excellent anti-protein adsorption endowed LZ/SA with a record-high adsorption capacity for bilirubin in the interference of serum albumin to simulate the physiological environment. The LZ/SA adsorbent also has effective adsorption capacity for heavy metals (Pb2+ , Cu2+ , Cr3+ , and Cd2+ ) and multiple antibiotics (terramycin, tetracycline, enrofloxacin, norfloxacin, roxithromycin, erythromycin, sulfapyrimidine, and sulfamethoxazole). Various adsorption functional groups exposed on the adsorbent surface significantly contribute to the excellent adsorption capacity. This fully bio-derived protein/alginate-based hemoperfusion adsorbent has great application prospects in the treatment of blood-related diseases.

Bioinspired and dual-functional nanocellulose aerogels for water disinfection and heavy metal removal

Treating water resources contaminated by pathogenic microorganisms and heavy metals is a great challenge because of the difficulties in developing efficient strategies for water treatment. Traditional adsorbent materials have the drawbacks of high cost, low adsorption efficiency, secondary pollution creation, and a lack of adaptability in removing a wide variety of pollutants. In this study, inspired by the hierarchical fibrous structure and antibacterial property of the natural silkworm cocoon, we developed a guanidine-functionalized sericin/nanocellulose aerogel (GSNA) with a biomimetic skeletal architecture, which holds great promise for achieving hybrid water disinfection and heavy metal removal. The nanocellulose (CNC) fibers integrated into a robust building block with an interconnected structure and mechanical stability. The grafted polyhexamethylene biguanide (PHMB) endows the biomimetic aerogel with exceptional bactericidal activity (7 log reduction against Escherichia coli within 30 min). Benefiting from the abundant surface functional groups on sericin and CNC-PHMB, the obtained aerogel also exhibits superior heavy metal adsorption capacity (571.5 mg/g for Cu). These compelling merits enable the aerogel to disinfect water and remove heavy metal ions simultaneously as a membrane filter. The synthesized GSNA can be a promising candidate for water disinfection and purification because of its facile preparation, cost-effectiveness, and environmentally friendly characteristics.

Equilibrium isotherm and kinetic study of biosorption of cadmium from synthetic water using wastes leaves of Averrhoa carambola

Globally, the discharge of heavy metals into the water bodies is a matter of serious concern. Heavy metals like cadmium are considered as toxic even at very low concentration. Several conventional methods are available to remove heavy metals from the wastewater. They bear high costs, generate high sludge, and consume high energy. Biosorbents provides many beneficial properties due to their good adsorption capacity for heavy metals. The present work focuses on the potential of waste leaves of Averrhoa carambola (WACLP) as an adsorbent for its ability to remove Cd (II) ions from synthetic water by batch experimental process. The adsorbent was characterized by using elemental analysis, Energy Dispersive X-ray or EDAX and Scanning Electron Micrograph (SEM). The batch experiment was carried out considering various parameters such as pH, initial metal ion concentration, contact time and dose of the adsorbent. The fitting of the experimental data was done by Langmuir, Freundlich and Temkin isothermal models. The study on isothermal models revealed that the experimental parameters were best fitted to the Langmuir isothermal model with R2 value of 0. 976.The Kinetic studies showed pseudo second order depicting chemisorption. The results showed that Averrhoa carambola is a good adsorbent for cadmium and hence it can widen the scope and prospects for future studies on heavy metal removal from the aqueous solution.