Elimination Of Heavy Metal Ions Research Articles

Efficient removal of heavy metal ions by modified cellulose prepared from rice husk: Equilibrium isotherms, Kinetics and desorption studies

The cellulose acetate was prepared from the naturally occurring cellulose extracted from rice husk. It was then characterized using FTIR, XRD, SEM/EDS, TEM and BET and the results were connected to their potential applications in the elimination of heavy metal ions. Differential pulse voltammetry was used for quantitative study of heavy metal ions. An adsorption experiment was conducted to study the effect of temperature, initial concentration, adsorbent dosage, pH and contact time on the adsorption capacity of cellulose acetate. The results of the adsorption experiment showed that the removal of metal ions from adsorbent was a pH-dependent, reaching its maximum adsorption capability at pH of 5-6. Adsorption process was effective with adsorbent dosage was 10±0.1 mg/mL and the temperature was kept at 303K. The adsorption properties of cellulose acetate can be effectively described by pseudo-second-order kinetic with lower error function value and adsorption isotherm such as Freundlich and Temkin adsorption model at 50 min contact time and 50±0.1 mg/L initial concentration. The thermodynamic parameters were investigated, they shows adsorption is favorable at low temperatures. Desorption and re-adsorption of the heavy metals were also studied. Cellulose acetate still retains its adsorption efficiency up to 6th cycles of adsorption.

UV-light-responsive Ag/TiO2/PVA nanocomposite for photocatalytic degradation of Cr, Ni, Zn, and Cu heavy metal ions

The rapid growth of industrialization has led to the uncontrolled pollution of the environment, and rapid action is needed. This study synthesized Ag/TiO2/polyvinyl alcohol (PVA) nano photocatalyst for promising light-derived photocatalytic removal of heavy metal ions. The design of experiment (DOE) was used to study the effect of important factors (pH, reaction time, and photocatalyst dosage) to maximize the final performance of the photocatalyst. In the optimized condition, the Ag/TiO2/PVA nano-photocatalyst removed more than 94% of Cr6+ in 180 min, and the efficiency was more than 70% for Cu2+, Zn2+, and Ni2+ metal ions. The adsorption of the heavy metal ions on the photocatalyst was described well with the Langmuir isotherm, while the pseudo-second-order linear kinetic model fitted with the experimental data. The nano-photocatalyst's stability was confirmed after maintaining its performance for five successive runs. The enhanced photocatalytic activity for the heavy metal ions removal can be attributed to the presence of metallic silver nanoparticles (electron transfer and plasmonic fields mechanisms) and PVA, which delayed the recombination of electron–hole. The synthesized ternary Ag/TiO2/PVA nano-photocatalyst showed promising performance for the elimination of heavy metal ions and can be used for environmental remediation purposes.

Preparation of PVA/SA-FMB Microspheres and Their Adsorption of Cr(VI) in Aqueous Solution

Biochar, a carbon-dense material known for its substantial specific surface area, remarkable porosity, diversity of functional groups, and cost-effective production, has garnered widespread acclaim as a premier adsorbent for the elimination of heavy metal ions and organic contaminants. Nevertheless, the application of powdered biochar is hindered by the challenges associated with its separation from aqueous solutions, and without appropriate management, it risks becoming hazardous waste. To facilitate its use as an immobilization medium, biochar necessitates modification. In this investigation, sodium alginate, celebrated for its superior gelation capabilities, was amalgamated with polyvinyl alcohol to bolster mechanical robustness, thereby embedding biochar to formulate sodium alginate biochar microspheres (PVA/SA-FMB). A meticulously designed response surface methodology experiment was employed to ascertain the optimal synthesis conditions for PVA/SA-FMB. Characterization outcomes unveiled a highly developed surface abundant in functional groups and confirmed the successful incorporation of iron ions. Adsorption trials revealed that at a temperature of 25 °C and a pH of 2, the adsorption capacity of PVA/SA-FMB for Cr(VI) was 13.7 mg/g within the initial 30 min, reaching an equilibrium capacity of 26.03 mg/g after 1440 min. Notably, the material sustained a Cr(VI) removal efficiency exceeding 90% across five cycles, underscoring its rapid and effective Cr(VI) eradication performance. Kinetic and isothermal adsorption analyses suggested that the adsorption of Cr(VI) adheres to a pseudo-second-order kinetic model and the Freundlich isotherm, indicative of monolayer adsorption dominated by reaction mechanisms. X-ray photoelectron spectroscopy (XPS) analysis inferred that the adsorption mechanism predominantly encompasses electrostatic attraction, redox processes, and complex formation.

A versatile MOF liquids-based Janus fibrous membrane towards complex oil/water separation and heavy metal ions removal

As an emerging material, porous liquids (PLs) have attracted wide attention and are applied in oily wastewater for the effective elimination of heavy metal ions due to their permanent pore structure, mobility, and superhydrophilicity. However, it remains a challenge to further enhance the separation performance of PLs. Here, a novel metal–organic framework (MOF) porous liquid was synthesized and mixed with a polyacrylonitrile (PAN) solution to produce an asymmetrical Janus fibrous membrane by electrostatic spinning technique. Benefiting from the synergistic effect of the electric field and self-migrating properties of MOF PLs, the Janus membranes exhibited ultrahigh flux of 25310.26 L m-2h−1 bar−1, outstanding separation efficiency (reaching up to 99.99 %) in various oil–water emulsions and high antimicrobial activity (>99.9 %). More impressively, the obtained Janus membranes maintained long-term stability, with separation efficiencies consistently as high as 99.5 %. Meanwhile, the porous structure of MOF PLs with abundant active sites and affinity of polyethylene glycol (PEG) flexible chain for metal ions facilitates the adsorption of metal ions with a maximum equilibrium adsorption capacity of 205 mg/g, which is superior to other literature reported. These results demonstrated that the versatile MOF PLs-based Janus fibrous membranes had a promising application prospect in addressing the challenges associated with such wastewater treatment.

Juice yield and pectin indicators in apple and carrot pomace

Background: Pectin exhibits different properties based on its degree of esterification, forming gels and serving as a structure-forming agent in food products, or forming complexes with heavy metal ions, finding applications in the development of therapeutic products for the elimination of heavy metal ions from the human body. Context and purpose of this study: The purpose of this study is to investigate the influence of enzymatic treatment on the yield and quality of apple and carrot juices, as well as the quality parameters of pectin in pomace. Our objectives were to select an enzymatic preparation for processing apple and carrot pomace and to study changes in the properties of pectins present in the pomace depending on the dosage of the enzyme preparation.Results: The results of our experiments revealed that for apple pomace processing, it is more beneficial to use the enzyme preparation Vegazym M with a dosage of 0.09% of the pomace mass, while for carrot pomace processing, the enzyme preparation Fructozym MA with a dosage of 0.07% of the pomace mass proved to be the most suitable. These enzyme preparations in the specified amounts ensure maximum juice yield. It has been established that changing the dose of enzymes changes the complexing properties of pectin, which allows its use in food products with therapeutic and prophylactic properties.Conclusions: The enzyme preparations allow for specific modifications, such as pectin modification in this case, enabling the versatile use of pectin as either a structure-forming agent or for the development of therapeutic and preventive food products.Keywords:Apple and carrot juices, enzyme preparations, apple and carrot pomace, pectin, soluble and insoluble pectin, degree of esterification and pectin complexation, functional products.

Ti3C2Tx/ZIF-67 hybrid nanocomposite as a highly effective adsorbent for Pb (II) removal from water: Synthesis and DFT calculations

The efficient elimination of heavy metal ions including Pb(II) from aqueous solutions, which provide serious risks for the human and environment, by various adsorbents has received much interest. Herein, Ti3C2Tx as a two-dimensional transition metal carbide (MXenes) and Ti3C2Tx/ZIF-67-belt were synthesized and employed as adsorbents for Pb(II) from contaminated water. The developed Ti3C2Tx/ZIF-67-belt hybrid nano-composite exhibited 526.3 mg.g−1 maximum capacity of adsorption for Pb(II), within only 15 min. Its excellent performance was related to the advantages of both the layered structure as well as the presence of different functional groups (Fluorine, Oxygen, Nitrogen, and hydroxyl groups). The results showed that Pb(II) adsorption equilibrium followed the Langmuir and its kinetics was based on pseudo-second-order models. The hybrid nanocomposite was simply regenerated and represented high reusability over six cycles. The features of a simple preparation method, excellent performance, regenerable, and high stability in aqueous solution provide the developed nanocomposite a promising candidate for adsorptive processes. Based on the DFT calculations, adsorption energy of Pb(II) on the MXene/ZIF-67-belt was found to be −0.8 eV as compared to + 0.3 eV for ZIF-67, confirmed that synergetic effects of MXene and ZIF-67 were in favor of Pb(II) adsorption due to the enhancement of charge transfer.

CHEMICALLY MODIFIED ASCOPHYLLUM NODOSUM SEAWEED: A SUSTAINABLE SOLUTION FOR HEAVY METAL REMOVAL FROM WASTEWATER

<p>In this study, a batch adsorption process was conducted utilizing Ascophyllum Nodosum biosorbent as an organic adsorbent used for the elimination of heavy metal ions (specifically chromium, nickel, and zinc) from wastewater. To examine the surface morphology and functional groups, the biosorbent underwent analysis using FTIR, SEM & EDX technologies. To understand the nature of the adsorption process, several isothermal studies were conducted. These studies aimed to determine whether the adsorption process was homogeneous or heterogeneous in nature. Furthermore, the physical or chemical nature of the metal ion adsorption on the adsorbent was investigated through kinetic studies. Thermodynamic investigations were also carried out to assess whether the adsorption of metal ions was exothermic or endothermic, as well as to conclude the spontaneity of the process. Notably, the findings indicated that the inclusion of 0.3N HCl resulted in the highest rate of desorption, indicating its effectiveness in releasing the adsorbed metal ions. The AN – Brown Algae adsorbs targeted metal ions (Cr(VI), Ni(II), Zn(II)) at percentage of 93.55%, 87.56% and 83.27% respectively from the synthetic solution under the optimum conditions in batch study.</p>

Chitosan Polymer Functionalized-Activated Carbon/Montmorillonite Composite for the Potential Removal of Lead Ions from Wastewater.

A simple approach for synthesizing a highly adsorbent composite was described for the uptake of heavy metal ions from wastewater. A simple approach for synthesizing a highly adsorbent composite was also described for the elimination of heavy metal ions from contaminated water. The nanocomposite was synthesized via a polymer grafting of chitosan on the activated carbon surface, followed by a stacking process with the layers of montmorillonite clay. The spectroscopic analyses were exploited to confirm the composite structure of the prepared materials. Various adsorption parameters, such as pH, initial concentration, and adsorption time, were assessed. The results showed that the adsorption capacity of the composite for Pb2+ ions increased as the pH increased until it reached pH 5.5. The maximum adsorption capacity was observed at an initial Pb2+ level of 20 mg/L and a contact time of 150 min. Kinetic models were evaluated, and the pseudo second-order model showed the best match. The adsorption isotherm data were processed by fitting the model with different isotherm behaviors, and the Langmuir isotherm was found to be the most suitable for the system. The maximum adsorption capacity for Pb2+ ion on the MMT/CS/AC composite was found to be 50 mg/g at pH 5.5. Furthermore, the composite maintained a high adsorption capability of 85% for five adsorption-desorption cycles. Overall, this composite is envisioned as an addition to the market of wastewater remediation technology due to its chemical structure, which provides influential functional groups for wastewater treatment.

Removal of heavy metal ions with magnetic carbon prepared from corncob biomass

Four novel magnetic-activated carbons (MACs) were prepared, characterized, and used as adsorbents to remove heavy metal ions from wastewater samples. The MACs prepared, are advanced adsorbents for the removal of Hg(II), Cr(III), Cd(II), and Pb(II). The nature of the acid, amount, composition of the MACs, and the remotion time were evaluated in aqueous solutions. The ions removal percentages obtained, under the best conditions, were 93% for Hg(II) and higher than 99% for Pb(II), Cr(III), and Cd(II) (100 mg L-1, initial concentration in solution), with 100 mg of the MAC-3 in HNO3 3 mM. The capacity of the best adsorbent, MAC-3, for removing heavy metals ions Hg(II), Cr(III), Cd(II), and Pb(II) was studied using Langmuir and Freundlich adsorption isotherms under the best condition. The maximum adsorption capacities of Hg(II), Cr(III), Cd(II), and Pb(II) were found to be 10.72, 11.51, 11.49 and 11.49 mg g−1, the values of constants of Freundlich models were 17.98, 26.83, 9.18, and 7.18 mg g−1 respectively. For Hg(II) and Pb(II) the correlation factor (R2) was better for Freundlich model, while Cr(III) and Cd(II) showed better R2 with Langmuir model. Finally, the treatment for the elimination of heavy metal ions was carried out, with wastewater samples of industrial and domestic origin, and used for crop irrigation. The samples were collected in Irrigation District 003, Hidalgo, Mexico. The MAC-3 removes heavy metal ions from the wastewater matrix above 99%.

Thiourea crosslinked-amino modified graphene nanoflakes as an effective adsorbent to confine Cr(VI) via multiple combination mechanisms

The high pathogenicity to organisms and high destructiveness in the natural environment determine the utmost importance of removing Cr(VI) from water. Herein, thiourea crosslinked-amino modified graphene nanoflakes (TAGN) was prepared by simple ring opening reaction and silanization reaction and the Cr(VI) adsorption performance was investigated. Results manifested that TAGN presented three-dimensional porous structure with abundant folds and avoided agglomeration. The adsorption experiments indicated that the optimal test pH value was 2 and the most suitable adsorbent dosage was 1 g/L. Under the optimum adsorption conditions, TAGN exhibited an outstanding adsorption capacity of 193.77 mg/g for Cr(VI) in water. Various characterizations and tests such as Zeta potential, FTIR, XPS as well as isotherms and kinetics revealed that the adsorption of TAGN for Cr(VI) was more consistent with Freundlich isotherm model and pseudo-second-order kinetic model, confirming a multilayer chemisorption process dominated by multiple combination mechanisms: electrostatic interaction, reduction reaction, complexation and hydrogen bonding interaction. Under the condition of coexistence of multiple metal ions, the TAGN could still maintain superb selectivity of 63.9% towards Cr(VI). After ten cycling test, 81.8% removal efficiency of Cr(VI) was guaranteed. Therefore, TAGN possessed high adsorption capacity, excellent selectivity and prominent cyclic regeneration ability. This work provided a promising nanosorbent for the field of water cleaning, especially for the elimination of heavy metal ions.

Surveying the elimination of hazardous heavy metal from the multi-component systems using various sorbents: a review.

In this review, several adsorbents were studied for the elimination of heavy metal ions from multi-component wastewaters. These utilized sorbents are mineral materials, microbes, waste materials, and polymers. It was attempted to probe the structure and chemistry characteristics such as surface morphology, main functional groups, participated elements, surface area, and the adsorbent charges by SEM, FTIR, EDX, and BET tests. The uptake efficiency for metal ions, reusability studies, isotherm models, and kinetic relations for recognizing the adsorbent potentials. Besides, the influential factors such as acidity, initial concentration, time, and heat degree were investigated for selecting the optimum operating conditions in each of the adsorbents. According to the results, polymers especially chitosan, have displayed a higher adsorption capacity relative to the other common adsorbents owing to the excellent surface area and more functional groups such as amine, hydroxyl, and carboxyl species. The high surface area generates the possible active sites for trapping the particles, and the more effective functional groups can complex more metal ions from the polluted water. Also, it was observed that the uptake capacity of each metal ion in the multi-component solutions was different because the ionic radii of each metal ion were different, which influence the competition of metal ions for filling the active sites. Finally, the reusability of the polymers was suitable, because they can use several cycles which proves the economic aspect of the polymers as the adsorbent.

Synthesis of trifunctional inorganic/organic hybrid nanocomposites and their applications for recognition and elimination of heavy metal ions

The core–shell nanoparticles with magnetic Fe3O4 as core and porous SiO2 as shell were synthesized by the hydrolysis and condensation of tetraethyl orthosilicate on Fe3O4 seed in an alkaline medium. Subsequently, the inorganic/organic hybrid nanocomposites based on core–shell Fe3O4@SiO2 nanoparticles were fabricated using “grafting-from” strategy, in which a macrocyclic dioxotetraamine (1,4,8,11-tetraazacyclotetradecane-5,7-dione, TACTDD) was grafted onto the end of Fe3O4@SiO2 surface. The as-synthesized nanocomposites possessed three functionalities: Firstly, the nanocomposites showed a selective fluorescence response toward Fe3+ ion with a detection limit of 6.0 × 10−7 mol/L, the eye-perceived fluorescence quenching under ultraviolet light could be used for the qualitative recognition of Fe3+ ion; Secondly, the nanocomposites were an excellent adsorbent, the adsorption efficiency for Fe3+ could reach 99.6% when the initial concentration was 200 mg/L without pH preadjustment, and over 85% for Zn2+, Hg2+ and Pd2+ ions. Moreover, the nanocomposites could be recycled by Na2EDTA, the desorption ratio of Fe3+, Zn2+, Hg2+ and Pd2+ ions only reduced slightly with six cycles, and all remained above 91%; Thirdly, the nanocomposites had superparamagnetism with a magnetization of 29.6 emu/g, this strong magnetic sensitivity can facilitate the sustainable removal of heavy metal ions in practical applications.

Synthesis of a new adsorbent poly(allylisothiocyanate‐co‐hydroxyethylmethacrylate‐co‐vinylimidazole) via photopolymerization: Characterization and investigation of heavy metal adsorption capacity

AbstractWe report the copolymerization synthesis of novel poly(allylisothiocyanate‐co‐hydroxyethylmethacrylate‐co‐vinylimidazole) (PAHV) adsorbents for potential applications in the heavy metal removals. In the present study, the copolymerization reaction was introduced by photopolymerization using benzophenone as the photoinitiator. The chemical structure in the PAHV adsorbents was monitored and evaluated by Fourier transform infrared spectroscopy, 1H‐nuclear magnetic resonance, andX‐ray photoelectron spectroscopy measurements. Surface analysis and molecular weight distribution of PAHV adsorbents were performed by scanning electron microscopy and gel permeation chromatography analysis, respectively. The adsorption method, which is one of the most effective techniques, was used for the elimination of heavy metal ions from aqueous solutions in this study. In order to understand the adsorption capacity and removal efficiency of heavy metal ions by PAHV, the effects of pH value and monomer ratio in the adsorbents were investigated. Inductively coupled plasma mass spectrometry device was used for these analyses. The optimum pH values for adsorption capacity and removal efficiency of heavy metal ions have been 6–8. The removal efficiency of heavy metal ions by the various PAHV adsorbents decreased in the order: Cd2+ > Pb2+ > Co3+ > Cr3+ > Ni2+ > Cu2+.

A novel material poly(N-acryloyl-L-glycine)-brush grafted N-doped magnetic biochar by surface-initiated RAFT polymerization for efficient elimination of heavy metal ions

To remove toxic and non-degradable heavy metal ions, a novel magnetically responsive polymer brush based on eco-friendly biochar was designed and prepared using reversible addition fragmentation chain transfer polymerization method. Subsequently, functional groups, structures, specific surface areas and morphologies of the material were characterized by FT-IR, SEM, BET, Raman and TGA. Then, the material was applied to remove Cr6+ and Cu2+. Additionally, a series of factors that might affect the adsorption were also explored, such as pH, salt concentration, time and temperature. Results concluded that the prepared material with abundant functional groups had excellent adsorption capacity of 34.84 and 112.94 mg/g, respectively for Cr6+ and Cu2+ at 318 K. Finally, characterization results of FT-IR and XPS indicated that adsorption mechanisms were primarily attributed to ion exchange, electrostatic interaction, cation-π bonding and hydrogen bonding. Based on experimental results, prepared material had excellent adsorption capacity, high cycle performance, quick magnetic separation performance, making it as a promising material for sewage treatment.

A Novel Material Poly(N-Acryloyl-L-Glycine)-Brush Grafted N-Doped Magnetic Biochar by Surface-Initiated Raft Polymerization for Efficient Elimination of Heavy Metal Ions

A Novel Material Poly(N-Acryloyl-L-Glycine)-Brush Grafted N-Doped Magnetic Biochar by Surface-Initiated Raft Polymerization for Efficient Elimination of Heavy Metal Ions

Alkynyl functionalized MoS2 mesoporous materials with superb adsorptivity for heavy metal ions

Effective elimination of heavy metal ions from water is an arduous task for their toxic effects to aquatic ecosystem and human health. Herein, a novel alkynyl functionalized molybdenum disulfide (C-MoS2) is fabricated via mechanochemical method with well interlayered spacing, meso porosity, and high surface area (~211 m2g−1). Mineral MoS2 was first peeled mechanically and oxidized in situ to MoS2−xOx, and then reduced by ball milling with CaC2 to form the C-MoS2 composite. The as-obtained C-MoS2 shows extraordinary adsorptivity for heavy metal ions, viz. 1194 mg-Hg g−1 (Hg(NO3)2 solution, pH= 5, 303.15 K, equilibrium Hg(II) concentration Ce= 36.9 μg·g−1, ionic strength I= 17.2 mmolL−1), and 442.3 mg-Pbg−1 (Pb(NO3)2 solution, pH= 5, 303.15 K, equilibrium Pb(II) concentration Ce= 46.9μgg−1, I= 5.8 mmolL−1), respectively, along with excellent recyclability, representing one of the best sorbents till now. The adsorption isotherms of Hg(II) followed the Langmuir model and the adsorption kinetics followed the pseudo-second-order model. The adsorption is an endothermic and entropy driven spontaneous process. The excellent adsorption performance of C-MoS2 is attributed to its very high S-content, availability, and soft acid-base interaction with mercury and lead anions. The C-MoS2 is an advanced sorbent for Hg(II) and Pb(II) with excellent adsorption performance and recyclability.

Investigation of mechanism of heavy metals (Cr6+, Pb2+& Zn2+) adsorption from aqueous medium using rice husk ash: Kinetic and thermodynamic approach

In this work, we examined the possibility on the application of rice husk as biosorbent for the elimination of heavy metal ions (chromium, lead, and zinc) existing in the aqueous solutions. The biosorbent was prepared from rice husk powder and modified with 0.1 N of HCl for creating the functional groups and increase specific surface area. The FT-IR spectra, SEM& EDX studies of rice hulls powder were examined for the pristine adsorbent and after the adsorption of heavy metal ions. The batch adsorption technique was adopted for this work and adsorption parameters were optimized. The maximum efficiency of adsorption is obtained at 6.0 pH, 1 h of contact duration, the rice husk dosage is 2.5 g/L, and temperature of 30°C for 25 mg/L of Cr, Pb & Zn metal ion solutions. The Cr, Pb & Zn metal ions are removed up to 87.12 %, 88.63 % & 99.28 %, respectively, using the rice husk powder. The adsorption process follows the Temkin & D-R isotherm model. Elovich model was fitted against the kinetic data of metal ion adsorption. Based on the experimental observations, the rice husk powder can be considered as a low cost adsorbent for heavy metal ion removal from the industrial effluent.

Review on toxic metal ions removal by using activated carbon prepared from natural biomaterials

Heavy metals has wide range of applications including industrial, domestic, medical, agricultural and technological field. Due to industrialization and urbanization variety of heavy metal ions are released in the environment. Toxicity of heavy metal ions depends on the route of exposure, media of exposure and its dose. Some of the metals, due to its high degree of toxicity are incorporated in CERCLA (Comprehensive Environmental Response, Compensation and Liability Act) priority list of hazardous substances. According to CERCLA, arsenic is the top most toxic metal followed by lead and mercury. These metals are proven to be carcinogens for human beings even at lower concentration. Contamination of water resources by toxic metal ions is a common problem since past years. There exists different methods for removal of toxic metal ions from waste water but adsorption is the most widely used and effective method. There are several adsorbents used for adsorption of toxic metal ions but, adsorbents prepared from low-cost and ecofriendly raw materials like coconut shells, rice husk, sugarcane bagasse, banana peels, potato peels, corncob, wheat straw, neem barks, almond shells and others are capturing researcher’s attention due to its easy availability and effective removal efficiency. This review highlights low cost adsorbents used for elimination of heavy metal ions from waste water and its other usage possibilities based on the literature study. This paper also highlights emerging potential bio-adsorbents which can provide maximum removal efficiency.

Preparation of cellulose acetate-Sn(IV) iodophosphate nanocomposite for efficient and selective removal of Hg2+ and Mn2+ ions from aqueous solution

The expansion of new materials for efficient elimination of heavy metal ions from water, is highly required to address various ecological issues. Herein, new nanocomposites (NCs) comprising of cellulose acetate (CA) and tin-iodophosphate (Sn(IV)IP) are prepared via sol-gel technique. The varying content of CA remarkably affects the shape, crystallinity, porosity and surface area of NCs. The prepared NCs were successfully employed for the selective removal of Hg2+ and Mn2+ ions from aqueous solution. The contact time, initial metal ion concentration, pH, and the amount of adsorbent were optimized prior to adsorption studies. Owing to different structural characteristics, different NCs have shown varying adsorption capacity. The maximum adsorption capacities of NCs for Hg2+ and Mn2+ were found to be 2500 and 1666.6 mg g−1, respectively. The removal efficiency of one of the NCs with maximum content of CA (2 w/w%) towards Hg2+and Mn2+ ions from water was found to be 91 % and 98 %, respectively. The mechanism and kinetics of adsorption is established using adsorption isotherms and kinetic models. This investigation is anticipated to demonstrate a platform for the preparation of NCs employing functional polymers to prepare eco-friendly composites along with manipulation of structural and functional properties of NCs.

Development of cost-effective and eco-friendly adsorbent by direct physical activation of Tanzanian Malangali kaolinite for efficient removal of heavy metals

The occurrence, toxicity and hazardous nature of heavy metals have prompted researchers to search for affordable and efficient adsorbents for their removal from the environment. Malangali kaolin clay is an abundant and eco-friendly local adsorbent material which can offer sustainable and cost-effective solution towards heavy metal remediation. Raw kaolin clay has the ability to scavenge heavy metals by improvement to its surface chemistry and adsorption capacity through modification. In this study, the feasibility of physically activated Tanzanian Malangali kaolin clay to sequester cobalt and cadmium ions from simulated wastewater was examined under batch process. The physical activation of pristine kaolin clay was carried out by thermal treatment at 300 °C to influence its adsorption efficiency and physicochemical properties. The clay sample was characterized by Fourier Transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), Nitrogen adsorption–desorption and chemical analysis by atomic absorption spectrometer (AAS). After thermal treatment of the pristine kaolinite, the specific pore volume and surface area amplified significantly from 0.454 − 0.813 cc/g and 78.69–83.046 m2/g, respectively. The heavy metal removal efficiency of thermally activated Malangali kaolinite (TAMK) was evaluated by investigating cobalt (Co2+) and cadmium (Cd2+) ions as potential water pollutants. The results obtained from batch experiments showed the elimination of heavy metal ions is greatly influenced by the initial concentration, adsorbent amount, contact time and solution pH. Adsorption isotherm studies revealed that Langmuir isotherm (R2 = 0.988 for Cd2+ and 0.979 for Co2+) presented the best fit to the equilibrium data than Freundlich isotherm (R2 = 0.965 for Cd2+ and 0.953 for Co2+) with cadmium ions being favourably adsorbed on TAMK compared to cobalt ions. Owing to improved surface area and porosity characteristics, TAMK displayed higher removal efficiency for both Co2+ and Cd2+ ions in simulated polluted water.