Adsorbent For Removal Of Heavy Metals Research Articles

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

Adsorptive removal of heavy metals from wastewater using Cobalt-diphenylamine (Co-DPA) complex

Heavy metals like Cadmium, Lead, and Chromium are the pollutants emitted into the environment through industrial development. In this work, a new diphenylamine coordinated cobalt complex (Co-DPA) has been synthesized and tested for its efficiency in removing heavy metals from wastewater, and its adsorption capacity was investigated. The effectiveness of heavy metals removal by Co-DPA was evaluated by adjusting the adsorption parameters, such as adsorbent dose, pH, initial metals concentration, and adsorption period. Heavy metal concentrations in real sample were 0.267, 0.075, and 0.125 mg/L for Cd2+, Pb2+, and Cr3+ before using as-synthesized Co-DPA to treat wastewater. After being treated with synthesized Co-DPA the concentration of heavy metals was reduced to 0.0129, 0.00028, 0.00054 mg/L for Cd2+, Pb2+, and Cr3+, respectively, in 80 min. The removal efficiency was 95.6%, 99.5%, and 99.5% for the respective metals. The adsorption process fitted satisfactorily with Freundlich isotherm with R2(0.999, 0.997, 0.995) for Cd2+, Pb2+, and Cr3+, respectively. The kinetic data obeyed the pseudo-second order for Cd2+ and Cr2+ and the pseudo-first order for Pb2+. Based on the results obtained within the framework of this study, it is concluded that the as-synthesized Co-DPA is a good adsorbent to eliminate heavy metal ions like Cd2+, Pb2+, and Cr3+from wastewater solution. In general, Co-DPA is a promising new material for the removal of heavy metal ions from water.Graphical

Carboxylic acid functionalized para-xylene based hypercrosslinked polymer as a novel and high performance adsorbent for heavy metal removal

In this work, hypercrosslinked polymeric adsorbent (HCP) was synthesized from para-Xylene precursor through Friedel-Crafts reaction. Additionally, heavy metal adsorption experiments from a multi component system including lead, cadmium, nickel, and copper ions were conducted. To enhance lead uptake selectivity over other metallic ions, the resulting HCP sample was functionalized through carboxylic acid incorporation into the HCP adsorbent skeleton. The adsorption process modeling was carried out by using Central Composite Design- Response Surface Methodology technique. In addition, the adsorption capability dependency of the resulting samples to the operational condition including temperature from 25 °C to 65 °C, solution pH value from 4 to 10, and solution initial concentration from 20 mg/l to 100 mg/l was investigated. Additionally, process optimization was applied aim to maximize the lead uptake selectivity, the optimal condition including a temperature of 31.8 °C, pH of 5.0, and initial concentration of 82.50 mg/l were obtained for HCP sample, also the optimal condition namely a temperature of 30 °C, pH of 5.5, and initial concentration of 100 mg/l were obtained for modified HCP sample. As a result of isotherm modeling, the Hill model was obtained as the best model, additionally, thermodynamically investigation of the process resulted in spontaneously and physically adsorption of the metallic ions by HCP samples, with respect to Gibbs free energy (ΔG0 < 0) and adsorption process enthalpy (ΔH0 < 20 kJ/mol). Finally, adsorbents regeneration were evaluated and minor losses in the adsorption capacity of samples were yielded after ten cycles.

Resourcization of Argillaceous Limestone with Mn3O4 Modification for Efficient Adsorption of Lead, Copper, and Nickel.

Argillaceous limestone (AL) is comprised of carbonate minerals and clay minerals and is widely distributed throughout the Earth's crust. However, owing to its low surface area and poorly active sites, AL has been largely neglected. Herein, manganic manganous oxide (Mn3O4) was used to modify AL by an in-situ deposition strategy through manganese chloride and alkali stepwise treatment to improve the surface area of AL and enable its utilization as an efficient adsorbent for heavy metals removal. The surface area and cation exchange capacity (CEC) were enhanced from 3.49 to 24.5 m2/g and 5.87 to 31.5 cmoL(+)/kg with modification, respectively. The maximum adsorption capacities of lead (Pb2+), copper (Cu2+), and nickel (Ni2+) ions on Mn3O4-modified argillaceous limestone (Mn3O4-AL) in mono-metal systems were 148.73, 41.30, and 60.87 mg/g, respectively. In addition, the adsorption selectivity in multi-metal systems was Pb2+ > Cu2+ > Ni2+ in order. The adsorption process conforms to the pseudo-second-order model. In the multi-metal system, the adsorption reaches equilibrium at about 360 min. The adsorption mechanisms may involve ion exchange, precipitation, electrostatic interaction, and complexation by hydroxyl groups. These results demonstrate that Mn3O4 modification realized argillaceous limestone resourcization as an ideal adsorbent. Mn3O4-modified argillaceous limestone was promising for heavy metal-polluted water and soil treatment.

The utilization of date palm waste as an efficient adsorbent for the elimination of heavy metals from polluted water.

This study focuses on the removal of heavy metal ions, such as cadmium (Cd2+), lead (Pb2+), chromium (Cr6+), and zinc (Zn2+) from water. Metals, which are often present in water, can have various origins, i.e., industrial emissions, mining, melting, corrosion, municipal, industrial waste, and agrochemicals. These metals have the potential to cause adverse effects on human health. The study employed activated carbon derived from date palm waste as a means of removing heavy metals. The activated nanoparticles were characterized using various analytical techniques, including SEM, ICP, XRD, BET, Raman, and FTIR analysis. Batch studies were conducted to optimize the metal ion adsorption onto the activated carbon of date palm waste. The adsorption process was evaluated using isotherm models and reaction kinetics under various conditions, including contact time, dosage, pH, and initial concentration. The findings of this study revealed that the prepared activated carbon from date palm waste effectively removed up to 85% of Cr6+, Pb2+, Cd2+, and Zn2+ ions from water. This study highlights the potential of using agricultural waste, to produce effective adsorbents for heavy metal removal.

Adsorptive Removal of Lead (II) Pollutants from Wastewater Using Corncob-Activated Carbon

he level of contamination in industrial wastewater has been a serious environmental challenge of our time. Various researchers have reported that the adsorption process using different adsorbents is a promising technique for treating heavy metal-contaminated wastewater. This study investigated the adsorptive removal of lead (II) from wastewater using corncob-activated carbon. Activated carbon was synthesized from a raw corncob. The synthesized activated carbon was applied as a sorbent in batch lead (II) adsorption in an aqueous lead (II) solution. Scanning electron microscopy, Fourier transformed infrared (FTIR), and Brunauer–Emmett–Teller (BET) theory characterized the synthesized activated carbon. A batch adsorption study investigated the effects of dosage, contact time, and the initial concentration of lead (II) on the sorption of Pb2+ on the synthesized activated carbon. The highest removal of lead recorded was 95 % at an adsorbent dosage of 2.5 g/L in 2 h. The highest adsorption capacity was 16.46 mg/g at the same conditions. The results showed that percentage removal increased with dosage and contact time but decreased with the initial metal ion concentration. Adsorption kinetics were best described with the pseudo-second-order kinetics, while the Langmuir isotherm model best fitted equilibrium adsorption in the study. The FTIR results showed the presence of several functional groups like carboxyl, hydroxyl, and amino, indicating good interaction with lead metal ions. The BET characterization revealed the activated corncob’s specific surface area and pore volume to be 249 m2/g and 0.164 cm3/g. This work shows that activated carbon can be synthesized from agricultural waste such as corncob and be used as an effective adsorbent for heavy metal removal, such as lead, from wastewater.

DOTA functionalized adsorbent DOTA@Sludge@Chitosan derived from recycled shrimp shells and sludge and its application for lead and chromium removal from water

DOTA@Sludge@Chitosan was synthesized by a facile treatment using DOTA (1,4,7,10-tetraazacyclododecane-N,N′,N,N′-tetraacetic acid) to modify dry sludge and chitosan in an acidic solution. The performance of developed DOTA@Sludge@Chitosan was investigated for the adsorptive removal of Cr6+ and Pb2+ from water. Characterization studies showed that the materials possess a large surface area (52.009 m2/g), pore volume (0.069 cm3/g), and abundant functional groups of amino and hydroxyl. The prepared material showed a synergetic effect due to carboxylic acid and sludge, effectively removing Cr6+ and Pb2+. It reached 329.4 mg/g (Pb2+) and 273.3 mg/g (Cr6+) at 20 °C, much higher than commercial activated carbon. The regeneration of the adsorbent was tested for six adsorption and desorption cycles. The results demonstrate that the DOTA@Sludge@Chitosan adsorbent well-maintained high adsorption capacity attributed to its stability, making it a promising adsorbent for heavy metals removal from industrial effluent.

Adsorptive removal of heavy metals, dyes, and pharmaceuticals: Carbon-based nanomaterials in focus

The use of carbon-based nanomaterials, including carbon nanotubes, carbon dots, graphene/graphene oxide, fullerene, and their derivatives, in the removal of emerging pollutants from wastewater has become a promising method in water treatment. These nanomaterials exhibit exceptional adsorption capabilities and selectivity due to their extensive surface area, customizable surface chemistry, and unique structural features, which involve factors like π-π interactions, electrostatic interactions, and specific surface functional groups. A notable experiment demonstrated the effectiveness of carbon nanotubes as adsorbents for removing Ismate violet 2R dye from contaminated water. The results showed a remarkable maximum removal efficiency of 91.71 % at a concentration of 10 mg/L within a brief 120-min period. This article conducts a comprehensive evaluation of the adsorptive removal of emerging pollutants from wastewater using carbon-based nanomaterials, with a focus on developments between 2015 and 2023. An in-depth bibliometric analysis of 1285 research publications retrieved from the Web of Science (WOS) and Scopus databases reveals a substantial increase in the number of publications, rising from 50 in 2015 to 158 in 2023. This signifies a burgeoning emphasis on both practical application and technological advancement in this domain. Furthermore, this review explores the intricacies of adsorption mechanisms, factors influencing the adsorption performance of carbon-based nanomaterials, and the associated challenges and limitations when applied in wastewater treatment. By thoroughly investigating these constraints and potential advantages, this article provides valuable insights for the development of future carbon-based nanomaterials, aiming to enhance their efficiency and expand their applications in the field of wastewater treatment.

The Effect of Chemical Treated Okra Waste for Heavy Metal Adsorption from Natural Gas Production Wastewater

Nowadays, one of the leading environmental pollutants is heavy metals. Hence, heavy metals in wastewater must be removed before discharge because they are toxic even at low concentrations. This research aims to evaluate the efficiency of okra waste as an adsorbent for heavy metals removal from wastewater in natural gas production. In this study, chemical activation of okra adsorbent was processed to increase the surface area of okra adsorbent for better adsorption, whenever the impregnation of the powdered okra waste was performed using phosphoric acid (H3PO4) as the impregnating agent. The okra powder was impregnated at a rate of 4: 1 (v / m). The FTIR was used to characterize the okra-activated carbon and the peaks showed the presence of functional groups such as Hydroxyl (OH), Amino (N-H), Carboxyl (C=O, C-O-C), C-0 stretching and M-O at 3390.05, 2905.5, 1640-1658, 1050.05 and 650 stretching bands respectively. Furthermore, the batch adsorption experiments were conducted via varying agitation speed, contact time, adsorbent dose and adsorbent particle sizes. The results showed that the maximum removal percent of Cd2+, Cu2+, Pb2­+, Zn 2+, Ag2+ and Ba2+metal ions had been observed to be at an agitation speed of 1000 rpm, contact time of 90 min­, okra adsorbent dose of 0.25 g and particle size of 1.00mm. The experimental findings show that okra wastes from agricultural by-products may be a low-cost adsorbent for future research to remove additional heavy metals owing to their high effectiveness in removing Cd2+, Cu2+, Pb2+, and Zn2+ ions from wastewater.

3D-Printed Filters for Efficient Heavy Metal Removal from Water Using PLA@CS/HAP Composites.

Chitosan/Hydroxyapatite composites, enriched with relatively active -NH2 and -OH groups, have emerged as promising adsorbents for heavy metal removal. In this study, we harnessed the potential of CS/HAP composites by developing monolithic PLA@CS/HAP filters utilizing 3D printing and freeze-drying techniques. These filters possess both macroscopic and microscopic porous structures, endowing them with exceptional capabilities for removing heavy metals from water. The adsorption properties of CS/HAP composites were explored by varying the dosage, duration, and initial concentrations of copper ions. The maximum adsorption capacity for Cu2+ was determined to be approximately 119+/-1 mg/g at the natural pH and 298 K. Notably, the monolithic PLA@CS/HAP filters demonstrated remarkable efficiency in the removal of copper ions, with 90% of copper ions effectively removed within a mere 2-h period in a cyclic adsorption experiment. Furthermore, the PLA@CS/HAP filters exhibited a robust dynamic Cu2+ removal capacity (80.8% or even better in less than 35 min) in a dynamic adsorption experiment. Importantly, all materials employed in this study were environmentally friendly. In summary, the PLA@CS/HAP filter offers advantages such as ease of preparation, eco-friendliness, versatility, and broad applicability in diverse wastewater treatment scenarios, thereby presenting a significant potential for practical implementation.

A novel double-network hydrogel made from electrolytic manganese slag and polyacrylic acid-polyacrylamide for removal of heavy metals in wastewater

Electrolytic manganese slag (EMS), a bulk waste generated in industrial electrolytic manganese production, can be a cost-effective adsorbent for heavy metals removal after appropriate modification. In this study, EMS was activated by NaOH and then used to make the EMS-based double-network hydrogel (an EMS/PAA hydrogel) via a one-pot method. The results showed that the EMS/PAA hydrogel exhibits a high selective adsorption capacity of 153.85, 113.63 and 54.35 mg·g−1 for Pb (II), Cd (II) and Cu (II), respectively. In addition, Density Functional Theory (DFT) suggests that the adsorption energies (Ead) of Pb, Cd and Cu on SiO2/PAA of the EMS/PAA gels are − 4.15, − 1.96, and − 2.83 eV, respectively, and SiO2/PAA, with a strong affinity to Pb2+, is one of the reasons for the selective adsorption capacity of EMS/PAA gel for Pb2+. The removal efficiency of the EMS/PAA gel for Pb2+, Cd2+, Cu2+ decreased after four adsorption-desorption cycles by 20.00 %, 24.56 % and 46.56 %, respectively. Mechanism studies suggested that the elimination of the heavy metals by EMS/PAA gels mainly involves electrostatic attraction, inner-sphere complexation, and coordination interactions. The EMS/PAA hydrogels not only have high adsorption capacity, but are also easy to prepare and circulate, making them ideal for practical applications.

Adsorption of mercury (II) ions on kaolinite from aqueous solutions: Isothermal, kinetic, and thermodynamic studies

AbstractDue to industrial activity, heavy metal contamination is present in water, air, and soil around the world. Due to this circumstance, serious environmental issues arise. Natural kaolin (NK) clay underwent batch processing to remove Hg2+. Scanner electron microscopy (SEM), energy dispersion spectroscopy (EDS), x‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) were used to analyze the morphological and chemical characteristics of kaolin. Investigations were done into how adsorption is impacted by contact duration, adsorbent dosage, temperature, and solution pH. Kaolin's BET surface area was found to be 8.085 m2/g, while its pore volume was found to be 0.0537 cm3/g. The best working conditions were found to be pH 6.81 and an equilibrium period of 90 min. It was discovered that the Langmuir isotherm model was the most suitable one. At 298, 308, and 318 K, respectively, the adsorption capacities of NK were calculated to be 10.964, 10.515, and 10.101 mg/g. The pseudo‐second‐order kinetic model agreed with this. It was revealed that NK had a maximum desorption efficiency of 91.36%. Through this process, the potential of NK as an eco‐friendly adsorbent for heavy metal removal was shown.

Bentonite Clay as an Alternative Adsorbent for Removal of Heavy Metals in wastewater

This study investigates the potential of bentonite clay as an alternative adsorbent for removing heavy metals from abattoir wastewater. Laboratory experiments were conducted to evaluate the effectiveness of bentonite clay in removing six heavy metals, including Lead, Chromium, Arsenic, Cadmium, Zinc and Iron. Results show that bentonite clay effectively removed all heavy metals, with removal efficiencies ranging from 75% to 95%. The study also found that the adsorption efficiency of bentonite clay increased with increasing initial metal concentration and decreasing pH of the solution. Freundlich and Langmuir models were used to predict the adsorption process, and the R2 values for both models were similar. This suggests that both models were equally adequate or inadequate in describing the process. The study concludes that bentonite clay is a promising adsorbent for removing heavy metals from wastewater. It is recommended that the use of bentonite clay as an alternative adsorbent for heavy metal removal should be further explored and optimized, particularly in terms of operating conditions such as pH, contact time, and adsorbent dosage.

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.

Adsorptive removal of heavy metals and organic dyes by sodium alginate/coffee waste composite hydrogel

Heavy metals and dyes used in technological applications have a detrimental influence on human health and the environment. The most used methods for removing pollutants depend on high-cost materials. Therefore, this research was conducted on cost-effective alternatives derived from natural resources and food waste. Herein, we designed a composite hydrogel based on sodium alginate/coffee waste (Alg/coffee) as adsorbent for the removal of organic and inorganic pollutants from aquatic solutions. The selectivity study displayed that Alg/coffee is more effective in adsorbing Pb(II) and acridine orange dye (AO). Adsorption of Pb(II) and AO was studied at concentration range of 0–170 mgL−1 and 0–40 mgL−1. Adsorption data of Pb(II) and AO reveals their fitting to Langmuir-isotherm and pseudo-second-order-kinetic models. The findings demonstrated that Alg/coffee hydrogel are more effective than coffee powder itself with an adsorption (%) approaching 98.44 % of Pb(II) and 80.53 % of AO. Real sample analysis reveals the efficiency of Alg/coffee hydrogel beads in Pb(II) adsorption. The adsorption cycle was examined four times providing high efficiency toward Pb(II) and AO. Desorption of Pb(II) and AO was easily performed using HCl eluent. Thus, Alg/coffee hydrogel beads could be promising adsorbent for the removal of organic and inorganic pollutants.

Adsorption characteristics of U(VI) in aqueous solution by chloroacetic acid-modified MXene-CS gel microspheres

To solve the problems of the poor stability and low adsorption efficiency of MXene used as an adsorbent for heavy metal removal. In this study, the microwave-assisted novel composite of chloroacetic acid-modified MXene-chitosan gel microspheres (C-TC-CS) was prepared. The experimental results demonstrated that C-TC-CS exhibited good stability and U(VI) adsorption performance, the maximum adsorption capacity of U(VI) by C-TC-CS was up to 141.96 mg/g. Pseudo-second-order and Langmuir isotherm adsorption models fit the adsorption process well, and the thermodynamic parameters showed that the adsorption process was spontaneous and endothermic. Importantly, C-TC-CS could be easily separated and regenerated. After five cycles of regeneration, the adsorption efficiency of C-TC-CS for U(VI) remained above 74%. Spectroscopic analyses indicated that the main adsorption mechanism involved electrostatic interactions, ion exchange, and complexation. This study proved that C-TC-CS could be an effective and promising adsorbent for removing U(VI) from aqueous solution.

Arsenic and TDS removal using antibacterial/antifouling nanofiltration membranes modified by functionalized graphene oxide and copper ferrodioxide.

The intrinsic hydrophilicity of metal compounds, such as copper ferrite (CuFe2 O4 ), and organic compounds, including graphene oxide (GO) and triethylenetetramine (TETA), make them promising adsorbents for heavy metals removal. The presence of lone pairs in these compounds is observed in modified polyethersulfone (PES) membranes used for the separation of arsenic (As) and total dissolved solids (TDS), including mono and divalent salts from aqueous solutions. The objective of this study was to investigate the performance of GO-TETA-CuFe2 O4 membranes for wastewater treatment applications. The membranes were characterized for their optimal mechanical strength (tensile strength) and high negative charge (zeta potential) on the surface. Separation tests were conducted at different pressures and pH levels to evaluate the membrane's effectiveness in removing contaminants. In addition, the membranes were examined for their antibacterial properties. The modified membrane exhibited superior performance compared to the control membrane, with TDS removal rates of 93.8%, As3+ removal rates of 81.2%, and As5+ removal rates of 87.9%. The contact angle of the modified membrane was reduced, resulting in an increase in pure water flux from 13.11 to 27.87 L/m2 .h. The modified membrane also demonstrated significantly higher resistance to fouling than the control membrane, with a resistance increase from 6.78×10+12 to 2.07×10+12 m-1 . This contributed to the improved separation performance of arsenic and TDS in a cross-flow setup. The results suggest that the GO-TETA-CuFe2 O4 modified membrane has great potential for use in water treatment applications.

Isotherms and Kinetic Studies of Copper Removal from Textile Wastewater and Aqueous Solution Using Powdered Banana Peel Waste as an Adsorbent in Batch Adsorption Systems.

Heavy metals that are present in surface water and wastewater are becoming a severe environmental problem. Because of its toxicity, heavy metal removal has become the main priority for environmental concerns. Banana peels are low-cost agricultural waste that could be used for heavy metal adsorption in wastewater. The main objective of this study is to evaluate the effective powdered banana peel for the removal of copper (II) from aqueous solutions and real wastewater. The banana peels were collected from domestic waste and ground to get a particle size of 150 µm. Powdered banana peel waste adsorbent (PBPWA) contained moisture content, ash content, volatile matter, and bulk density of 3.8%, 3.5%, 37.5%, and 0.02 g/cm3, respectively. The Fourier-transform infrared spectroscopy (FTIR) results showed that the alkyne, aldehyde, and amide functional groups were dominant in the powdered banana peel surface, and the scanning electron microscope showed the morphology of the adsorbent. Physicochemical characteristics of the raw wastewater revealed that the concentration of Cu (II), Pb (II), COD, BOD5, and Cd (II) were 2.75 mg/L, 2.02 mg/L, 612.16 mg/L, 185.35 mg/L, and 0.01 mg/L, respectively. At pH 5, adsorbent dose of 2g/100 mL, initial copper (II) concentration of 80 mg/L, and contact time of 90 min, the maximum removal efficiency of synthetic wastewater was 96.8% and textile wastewater was 69.0%. The adsorption isotherm fitted well with the Langmuir isotherm model at R2 = 0.99. The kinetics of copper (II) adsorption followed the second-order kinetic model better. Finally, these studies showed that banana peel bio-adsorbent is a potential adsorbent for heavy metal removal from synthetic and textile wastewater.

Adsorptive Elimination of Heavy Metals from Aqueous Solution Using Magnetic Chitosan/Cellulose-Fe(III) Composite as a Bio-Sorbent.

Magnetic chitosan/cellulose nanofiber-Fe(III) [M-Ch/CNF-Fe(III)] composites were isolated for the elimination of Cr(VI), Cu(II), and Pb(II) from aqueous solution. Various analytical methods, such as field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), and thermogravimetric analysis (TGA) were employed to determine the morphological, physicochemical, and thermal properties of the isolated M-Ch/CNF-Fe(III) composites. It was found that the M-Ch/CNF-Fe(III) composites were porous materials, and they have the potential to be implemented as an adsorbent for heavy metals removal. The adsorption efficiency of M-Ch/CNF-Fe(III) composites was determined for Cr(VI), Cu(II), and Pb(II) elimination with changing pH (pH 1.0-8.0), adsorbent doses (0.05-1.0 g), time (15-90 min), and temperature (28-80 °C). In addition, isothermal and kinetics studies were conducted to assess the adsorption behavior and mass transfer phenomena of M-Ch/CNF-Fe(III) composites as an adsorbent for Cr(VI), Cu(II) and Pb(II) elimination from aqueous solution. The outcomes of the present study reveal that the M-Ch/CNF-Fe(III) composites could be utilized as an adsorbent for the Cr(VI), Cu(II), and Pb(II) elimination from industrial effluents.

Green synthesis of iron oxide nanobiocomposite for the adsorptive removal of heavy metals from the drinking water

The current study aimed to synthesize and characterize the Duranta erecta leaves extract-based iron oxide nanoparticles (D-Fe3O4-NPs) and chitosan biopolymer-based nanocomposites (D-Fe3O4-NC). The synthesized D-Fe3O4-NC was applied for the adsorptive removal of cadmium (Cd), chromium (Cr), and lead (Pb) from water. The nanostructure, porous, rough, crystalline structure, and different functional groups of chitosan and D-Fe3O4-NPs in D-Fe3O4-NC showed that the D-Fe3O4-NC is feasible for suitable adsorbents for quantitative removal of Cd, Cr, and Pb. Based on the batch experiments, the influences of pH, adsorption time, contents of Cd, Cr, and Pb in solution, and temperature were successfully optimized. The adsorption capacities of D-Fe3O4-NC for Cd, Cr, and Pb were observed at 74.4, 76.0, and 75.2 mg g−1, respectively. The adsorption isotherms fitted the Freundlich Model equation well, and the adsorption kinetics followed pseudo-second-order kinetics for the adsorption of these toxic metals. D-Fe3O4-NC showed an excellent recyclable efficiency up to multiple analyses (n = 20). The D-Fe3O4-NC was an excellent adsorbent for removing toxic metals from municipal and hand pump water samples (% removal >93%). Therefore, the proposed D-Fe3O4-NC is the most efficient and selective adsorbent for removing Cd, Cr, and Pb from drinking water up to recommended permissible limit.