Remediation Of Heavy Metal Ions Research Articles

Nanocellulose: A sustainable functional construct for the remediation of heavy metal ions from water

Heavy metals are considered to be a significant pollutant in water bodies, adversely affecting human health by causing various severe diseases after passing down the food chain. The rise in environmental problems due to the usage of non – biodegradable materials leads to the necessity of eco–friendly materials. The abundant and eco-friendly nature of the nanocellulose makes them promising substitutes for non-sustainable materials, nowadays. It is also possible to find the chemical components (cellulose, hemicellulose, and lignin) present in a source and the cellulose yield. In this context, nanocellulose has gained considerable attention among nanomaterials as a promising candidate for the adsorption of toxic heavy metal ions because of its large surface area, light weight, low cost, biocompatible nature, etc. Moreover, the numerous surface hydroxyl groups present in its surface make them suitable for the wide range of surface functionalization with different groups. They can thus be used individually or in combination with other materials for excellent adsorption towards various toxic heavy metal ions. The state of research on modified nanocellulose as an adsorbent for heavy metals is principally discussed in this review. Mainly two types of plant-based nanocelluloses; cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs), are discussed in detail in this review. The extraction of nanocellulose via a green approach was also covered. This review comprises comprehensive details on the modifications and other relevant properties of nanocellulose which would facilitate the adsorption of toxic heavy metals.

Fiber welded EDTA-modified cellulose for remediation of heavy metal ions

Ethylenediaminetetraacetic acid (EDTA) is a well-known metal chelator and an attractive ligand for covalently modifying adsorbents for bioremediation. Cellulose, a naturally occurring biopolymer, has immense potential as an inexpensive, earth abundant, biocompatible scaffold for EDTA-facilitated environmental remediation; however, pretreatment of the material is required to achieve sufficient degrees of chemical modification. In this study, Natural Fiber Welding (NFW) is used to prepare commercial cotton Aida cloth for EDTA functionalization. Following NFW, the cotton scaffold was covalently modified with up to 0.56 mmol of EDTA per gram of adsorbent, a nearly 2.5-fold increase over native material. The welded EDTA-modified substrates were tested qualitatively against cobalt and quantitatively against nickel, reaching equilibrium binding capacities (qe) of up to 46 mg metal per g of adsorbent, on par with capacities reported from past work on EDTA-modified cellulose. In addition, adsorbent material could be regenerated using mild acid treatment with no significant loss in qe. Unlike the controls, the fiber-welded EDTA-Aida did not fray even after 3 chelation cycles, indicating enhanced textile robustness afforded through NFW treatment. Overall, NFW offers a new approach to converting commercially available, sustainable biomaterials into robust adsorbents for environmental remediation.

Polyrhodanine-Functionalized Magnetic-Activated Carbon for Efficient Removal of Lead Ions and Malachite Green From Wastewater

The development of wastewater treatment agents with high treatment capacity and efficient separation is crucial for the remediation of heavy metal ions and organic dye wastewater. In this study, a polyrhodanine functional magnetic-activated carbon composite (PR-mAC) was synthesized via a one-step co-precipitation method combined with chemical oxidation polymerization. As an innovative water treatment agent, PR-mAC possesses not only environmentally friendly and easily obtainable raw materials but also magnetic properties that facilitate its reusability. Notably, PR-mAC exhibited remarkable removal efficiency towards lead ion (Pb(II)) and malachite green (MG). Experimental results demonstrated that the adsorption of Pb(II) and MG followed quasi-second-order kinetic model, while the Hill isothermal adsorption model and Redlich–Peterson isothermal adsorption model were suitable for Pb(II) and MG removal, respectively. All adsorption processes were spontaneous endothermic reactions. The maximum adsorption capacities reached 223.71 mg/g and 315.46mg/g, respectively. Even after undergoing 5 cycles, the material maintained satisfactory removal performance for Pb(II) and MG pollutants. Therefore, the prepared PR-mAC represents an optimal agent for wastewater treatment due to its effective capability in removing both metal ions and dyes.

Engineered Bacillus subtilis Biofilm@Biochar living materials for in-situ sensing and bioremediation of heavy metal ions pollution

The simultaneous sensing and remediation of multiple heavy metal ions in wastewater or soil with microorganisms is currently a significant challenge. In this study, the microorganism Bacillus subtilis was used as a chassis organism to construct two genetic circuits for sensing and adsorbing heavy-metal ions. The engineered biosensor can sense three heavy metal ions (0.1–75 μM of Pb2+ and Cu2+, 0.01–3.5 μM of Hg2+) in situ real-time with high sensitivity. The engineered B. subtilis TasA-metallothionein (TasA-MT) biofilm can specifically adsorb metal ions from the environment, exhibiting remarkable removal efficiencies of 99.5% for Pb2+, 99.9% for Hg2+and 99.5% for Cu2+ in water. Furthermore, this engineered strain (as a biosensor and absorber of Pb2+, Cu2+, and Hg2+) was incubated with biochar to form a hybrid biofilm@biochar (BBC) material that could be applied in the bioremediation of heavy metal ions. The results showed that BBC material not only significantly reduced exchangeable Pb2+ in the soil but also reduced Pb2+ accumulation in maize plants. In addition, it enhanced maize growth and biomass. In conclusion, this study examined the potential applications of biosensors and hybrid living materials constructed using sensing and adsorption circuits in B. subtilis, providing rapid and cost-effective tools for sensing and remediating multiple heavy metal ions (Pb2+, Hg2+, and Cu2+).

Amine-functionalized UiO-66 incorporated electrospun cellulose/chitosan porous nanofibrous membranes for removing copper ions

Cellulose (CE)/chitosan (CS)/amine-functionalized zirconium 1, 4-dicarboxybenzene metal–organic framework (UiO-66-NH2) porous nanofiber membranes were prepared by direct electrospinning and surface in-situ growth and then used to remove copper ions (Cu2+) from polluted water. The micro-morphology, porosity, thermal stability, chemical groups, crystallographic structure, and adsorption performance of CE/CS/UiO-66-NH2 nanofibrous membranes were characterized. The hydrophilicity, thermal stability, and adsorption capacity of the membranes were greatly improved by incorporating UiO-66-NH2. The direct electrospinning CE/CS/UiO-66-NH2 nanofibers displayed the irregular, bumpy shapes and large fiber diameters (768.99–1039.74 nm). They also increased the chemical active sites due to the effective and uniform combination of UiO-66-NH2 with nanofibers. This resulted in a superior adsorption performance than the one with in-situ preparation. The CE/CS/UiO-66-NH2-5 showed the highest adsorption capacity of 121.16 mg g−1 and a removal rate of 90.69 %. The optimal Cu2+ adsorption conditions were obtained at an initial Cu2+ concentration of 100 mg L-1 and in weakly acidic media (pH = 5). The Langmuir model was optimal to describe Cu2+ adsorption of the nanofibrous membranes. The adsorption process involved both physical adsorption with chemical adsorption. This provides a novel strategy to combine metal–organic frameworks with the natural biomasses via electrospinning, which shows a promising application for efficient remediation of heavy metal ions in wastewater.

Agricultural Solid Wastes Based Adsorbent Materials in the Remediation of Heavy Metal Ions from Water and Wastewater by Adsorption: A Review.

Adsorption has become the most popular and effective separation technique that is used across the water and wastewater treatment industries. However, the present research direction is focused on the development of various solid waste-based adsorbents as an alternative to costly commercial activated carbon adsorbents, which make the adsorptive separation process more effective, and on popularising the sustainable options for the remediation of pollutants. Therefore, there are a large number of reported results available on the application of raw or treated agricultural biomass-based alternatives as effective adsorbents for aqueous-phase heavy metal ion removal in batch adsorption studies. The goal of this review article was to provide a comprehensive compilation of scattered literature information and an up-to-date overview of the development of the current state of knowledge, based on various batch adsorption research papers that utilised a wide range of raw, modified, and treated agricultural solid waste biomass-based adsorbents for the adsorptive removal of aqueous-phase heavy metal ions. Metal ion pollution and its source, toxicity effects, and treatment technologies, mainly via adsorption, have been reviewed here in detail. Emphasis has been placed on the removal of heavy metal ions using a wide range of agricultural by-product-based adsorbents under various physicochemical process conditions. Information available in the literature on various important influential physicochemical process parameters, such as the metal concentration, agricultural solid waste adsorbent dose, solution pH, and solution temperature, and importantly, the adsorbent characteristics of metal ion removal, have been reviewed and critically analysed here. Finally, from the literature reviewed, future perspectives and conclusions were presented, and a few future research directions have been proposed.

Silk based adsorbents for remediation of heavy metal ions from wastewater

Silk, a natural biopolymer possessing superior adsorbent properties, is excessively utilized in water remediation. This study illustrates degumming of silk fibroin using microwave radiations and batch adsorption of nickel ions from aqueous (aq.) solution. The removal of sericin from silk was confirmed through surface, functional group and thermal analysis. The water contact angle of degummed silk was observed to be 163°, exhibiting superhydrophobicity. The degummed silk fibroin demonstrated superior adsorption capacity of 27 mg/g in contrast with raw silk of 17 mg/g at constant adsorbent dose and contact time, and the former exhibited lowered adsorption time by 2 h compared to the latter.

Facile Strategy for Fabricating an Organosilica-Modified Fe3O4 (OS/Fe3O4) Hetero-nanocore and OS/Fe3O4@SiO2 Core-Shell Structure for Wastewater Treatment with Promising Recyclable Efficiency.

The development of a sustainable process for heavy metal ion remediation has become a point of interest in various fields of research, including wastewater treatment, industrial development, and health and environmental safety. In the present study, a promising sustainable adsorbent was fabricated through continuous controlled adsorption/desorption processes for heavy metal uptake. The fabrication strategy is based on a simple modification of Fe3O4 magnetic nanoparticles with organosilica in a one-pot solvothermal process, carried out in order to insert the organosilica moieties into the Fe3O4 nanocore during their formation. The developed organosilica-modified Fe3O4 hetero-nanocores had hydrophilic citrate moieties, together with hydrophobic organosilica ones, on their surfaces, which facilitated the further surface coating procedures. To prevent the formed nanoparticles from leaching into the acidic medium, a dense silica layer was coated on the fabricated organosilica/Fe3O4 (OS/Fe3O4). In addition, the prepared OS/Fe3O4@SiO2 was utilized for the adsorption of cobalt(II), lead(II), and manganese(II) from the solutions. The data for the adsorption processes of cobalt(II), lead(II), and manganese(II) on OS/(Fe3O4)@SiO2 were found to follow the pseudo-second-order kinetic model, indicating the fast uptake of heavy metals. The Freundlich isotherm was found to be more suitable for describing the uptake of heavy metals by OS/Fe3O4@SiO2 nanoparticles. The negative values of the ΔG° showed a spontaneous adsorption process of a physical nature. The super-regeneration and recycling capacities of the OS/Fe3O4@SiO2 were achieved, comparing the results to those of previous adsorbents, with a recyclable efficiency of 91% up to the seventh cycle, which is promising for environmental sustainability.

Nanovesicle and extracellular polymeric substance synthesis from the remediation of heavy metal ions from soil

Heavy metal toxicity affects aquatic plants and animals, disturbing biodiversity and ecological balance causing bioaccumulation of heavy metals. Industrialization and urbanization are inevitable in modern-day life, and control and detoxification methods need to be accorded to meet the hazardous environment. Microorganisms and plants have been widely used in the bioremediation of heavy metals. Sporosarcina pasteurii, a gram-positive bacterium that is widely known for its calcite precipitation property in bio-cementing applications has been explored in the study for its metal tolerance ability for the first time. S. pasteurii SRMNP1 (KF214757) can tolerate silver stress to form nanoparticles and can remediate multiple heavy metals to promote the growth of various plants. This astounding property of the isolate warranted extensive examinations to comprehend the physiological changes during an external heavy metal stress condition. The present study aimed to understand various physiological responses occurring in S. pasteuriiSRMNP1 during the metal tolerance phenomenon using electron microscopy. The isolate was subjected to heavy metal stress, and a transmission electron microscope examination was used to analyze the physiological changes in bacteria to evade the metal stress. S. pasteurii SRMNP1 was tolerant against a wide range of heavy metal ions and can withstand a broad pH range (5–9). Transmission Electron Microscopy (TEM) examination of S. pasteurii SRMNP1 followed by 5 mM nickel sulfate treatment revealed the presence of nanovesicles encapsulating nanosized particles in intra and extracellular spaces. This suggests that the bacteria evade the metal stress by converting the metal ions into nanosized particles and encapsulating them within nanovesicles to efflux them through the vesicle budding mechanism. Moreover, the TEM images revealed an excessive secretion of extracellular polymeric substances by the strain to discharge the metal particles outside the bacterial system. S. pasteurii can be foreseen as an effective bioremediation agent with the potential to produce nanosized particles, nanovesicles, and extracellular polymeric substances. This study provides physiological evidence that, besides calcium precipitation applications, S. pasteurii can further be explored for its multidimensional roles in the fields of drug delivery and environmental engineering.

Silver-chitosan (Ag-CH) nanocomposite hydrogel for remediation of aqueous medium

In this work, a low cost, in situ synthesized silver-chitosan (Ag-CH) nanocomposite hydrogel has been proposed for the detection and rapid removal of hexavalent chromium from water. Silver nanoparticles are enmeshed in a network of highly porous chitosan-based hydrogel matrix for the effective detection and removal hexavalent chromium. The in situ reduction of silver nitrate to silver nanoparticles within the chitosan blended polymer matrix ensures the high stability of AgNPs and the resulting Ag-CH nanocomposite acts as a colorimetric sensor for hexavalent chromium [Cr (VI)] with enhanced lower detection limit (LoD) of upto 0.1 ppb. Physico-chemical properties of the prepared Ag-CH nanocomposite hydrogel are studied using UV–Visible spectroscopy, FESEM and FTIR analysis. The Ag-CH nanocomposite shows high porosity and cross-linking, which makes it ideal as a biocompatible, low-cost and sustainable biosorbent material. The hydrogel has a high removal efficiency of 83 % for Cr (VI). The effortless regeneration of the nanocomposite hydrogel aids in its easy reusability. The biocompatibility, sustainability and reusability of the Ag-CH hydrogel confirms its effectiveness as a nanobiosorbent material and provides a potential solution for simultaneous sensing and remediation of heavy metal ions from aqueous matrices.

Highly efficient and simultaneous remediation of heavy metal ions (Pb(II), Hg(II), As(V), As(III) and Cr(VI)) from water using Ce intercalated and ceria decorated titanate nanotubes

Presence of heavy metal ionic contaminants in water is a matter of global concern, owing to their disastrous impact on human health and environment. Cerium intercalated, ceria decorated titanate nanotubes (CCTNT) was developed for efficient adsorption of toxic heavy metal ions: Pb(II),Hg(II),As(V),As(III) and Cr(VI) from water. The phase and structure of the material was confirmed using XRD, FTIR and Raman analysis. The TEM images established the morphology. The chemical properties of the surface were confirmed using the EDS and XPS analysis. The surface area was measured using the BET method. The adsorptive properties of CCTNT were evaluated in the batch mode. It was observed that CCTNT, with wide pH window for adsorption of heavy metal ions, is applicable for both groundwater and wastewater remediation. In addition, it exhibited ultrafast adsorption of all five contaminants using a low adsorbent dosage. The Langmuir adsorption capacities of the adsorbent were calculated to be 66.76, 97.18, 189.59, 199.80, 288.23 mg/g respectively for the removal of Cr(VI),Pb(II),As(V), Hg(II) and As(III) from water. CCTNT is further suitable for highly efficient and simultaneous removal of all five heavy metal ions water. These attractive properties make CCTNT a superior material for adsorption of heavy metal ions from water.

Effective adsorption of cadmium and lead using SO3H-functionalized Zr-MOFs in aqueous medium

Cadmium (Cd) and Lead (Pb) from industrial wastewater can bioaccumulate in the living organisms of water bodies, posing serious threats to human health. Therefore, efficient remediation of heavy metal ions of Cd (II) and Pb (II) in aqueous media is necessary for public health and environmental sustainability. In the present study, water stable Zirconium (Zr) based metal organic frameworks (MOFs) with SO3H functionalization were synthesized by solvothermal method and used first time for the adsorption of Cd (II) and Pb (II). Synthesis of UiO-66-SO3H, nano-sized (<100 nm) MOFs, was confirmed by FTIR, XRD, FESEM and BET. Effects of contact time, pH and temperature were investigated for adsorption of Cd (II) and Pb (II) onto SO3H-functionalized Zr-MOFs. The UiO-66-SO3H displayed notable rejections of 97% and 88% towards Cd (II) and Pb (II), respectively, after 160 min at 25 °C and pH (6) with an initial concentration of 1000 mg/L. Adsorption capacities of Cd (II) and Pb (II) were achieved as 194.9154 (mg/g) and 176.6879 (mg/g), respectively, at an initial concentration of 1000 mg/L. The Pseudo second-order kinetic model fitted well with linear regression (R2) of value 1. The mechanism was confirmed mainly as a chemisorption and coordination interaction between sulfone group (-SO3H) and metal ions Cd (IIa) and Pb (II). These results may support effective adsorption and can be studied further to enrich and recycle other heavy metals from wastewater.

A review on the use of cellulose nanomaterials for wastewater remediation of heavy metal ions

A review on the use of cellulose nanomaterials for wastewater remediation of heavy metal ions

Biogenic Synthesis of Magnetite Nanoparticles Using Leaf Extract of Thymus schimperi and Their Application for Monocomponent Removal of Chromium and Mercury Ions from Aqueous Solution

Currently, plant templated synthesis of magnetite iron oxide nanoparticles (Fe3O4 NPs) was emerged for multifunctional purposes. In this study, the leaf extract of the plant Thymus schimperi was utilized to synthesize Fe3O4 NPs. The synthesized NPs were characterized by using technical tools such as X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis, and ultraviolet-visible (UV-Vis) spectroscopy, and thermal analysis (TGA-DTA). The XRD result corroborated the presence of desired phase formation having pure cubic face centered phase structure with average crystallite particle size ranging from 20 nm to 30 nm. SEM micrographs confirmed microstructural homogeneities and remarkably different morphology of Fe3O4 NPs. Mercury (II) and chromium (VI) removal efficiencies of Fe3O4 NPs were found to be 90% and 86% from aqueous solution at initial concentration of 20 mg/L, respectively. Various factors which affect the metal ion removal efficiency such as metal ion initial concentrations, pH, contact time, and adsorbent dosage were also studied. The optimum pH and contact time for chromium ion adsorption were pH 5 and 60 min and that of mercury were observed to be pH 7 and 90 min, respectively. The Langmuir isotherm was best fitted for sorption of Hg(II) ion, and the Freundlich isotherm was best fitted with sorption of Cr(VI) ion onto the surface of Fe3O4 NPs. The mechanism of adsorption of both Hg(II) and Cr(VI) ions was obeyed pseudo 2nd order kinetics. The recorded percent removal efficiencies revealed that these Fe3O4 NPs synthesized through leaf extract of the plant called Thymus schimperi have demonstrated excellent potentiality in the remediation of heavy metal ions. The synthesized Fe3O4 NPs were regenerated (reused) for adsorptive removal of Hg(II) and Cr(VI) for five consecutive cycles without significant loss of removal efficiency. Fe3O4 NPs were reused with only 4.17% loss of removal efficiency against Hg(II) and only 3% loss of removal efficiency against Cr(VI) metal ions.

A silanized magnetic amino-functionalized carbon nanotube-based multi-ion imprinted polymer for the selective aqueous decontamination of heavy metal ions

A novel adsorbent comprising a silanized magnetic amino-functionalized carbon nanotube-based multi-ion imprinted polymer is introduced as an ideal candidate for the simultaneous and selective adsorptive remediation of heavy metal ions from contaminated water.

Green adsorbents for the removal of heavy metals from Wastewater: A review

The adsorption process has proved to be one of the most promising techniques for the treatment of wastewater containing toxic heavy metals. The cost of the activated carbon-based adsorption technique is rising due to the depletion of coal-based commercial activated carbon. Green adsorbents originating from agricultural waste, agricultural residue and agricultural by-products are being explored as the low-cost adsorbents for the remediation of heavy metal ions from aqueous solution. This paper presents a review of the application of green adsorbents for the reduction of heavy metal ions from the aqueous solution. The application of green adsorbents derived from agricultural waste, agricultural residue and agricultural by-products have been discussed in detail. The adsorption kinetic models and equilibrium adsorption isotherms used in recent studies for the reduction of heavy metal ions are also reviewed and discussed.

Assessment of 3-amino-1H-1,2,4-triazole modified layered double hydroxide in effective remediation of heavy metal ions from aqueous environment

Chemical modification of layered double hydroxide MgCuAl (LDH) to obtain its modified form using 3-amino1H-1,2,4-triazole (MLDH) MgCuAl during its synthesis by co-precipitation method. The fabricated LDH and their modified form were established using XRD, FTIR, XPS, TEM, SEM and BET N2 adsorption–desorption techniques. The prepared LDH and MLDH were evaluated as efficient adsorbents during the remediation of copper and cadmium ionic species in the solution medium. The variables of the adsorption process including the mass of used adsorbents, the acidity of the medium, and concentration of ionic species in the medium, temperature, and process time were examined. The results were used to optimize the adsorption process efficiency of both metal ions. The adsorption capacity of Cu2+ and Cd2+ was raised from 593 mg/g and 326 mg/g for LDH to 639 mg/g and 457 mg/g for MLDH, respectively. MLDH showed the optimized efficiency for Cu2+ and Cd2+ after 180 min, using 0.4 g/L of the adsorbent, in alkaline medium (pH = 9) at 25 °C. The isotherm model of the adsorption path was followed up by the Freundlich isotherm and the kinetic model was followed by the pseudo-second-order model.

Layered double hydroxides as amendment for remediation of heavy metal ions in water and soil

Layered double hydroxides as amendment for remediation of heavy metal ions in water and soil

Chemical behaviours of Arsenium, Chromium, Mercury, Lead, and Strontium in aqueous system

Over the decades, the application of heavy metals and the expansion of civilization resulted in severe pollutions in aqueous solutions. The poor degradation of toxic heavy metal contaminants in hydrosphere undoubtedly posed a huge threat to environmental safety and biological health. In this review, as most common heavy metal pollutants, arsenium (As), chromium (Cr), mercury (Hg), lead (Pb), and strontium (Sr) were introduced in detail. The chemical behaviours, chemical status, biological toxicity, and migration of mentioned contaminants were summarized. This work highlighted and reviewed the basic information of five heavy metal pollutants, which provided a new direction of toxic heavy metal ion remediation.

Adsorption Properties of Hydrated Cr3+ Ions on Schiff-base Covalent Organic Frameworks: A DFT Study.

Considering the superior physiochemical property, increasing efforts have been devoted to exploiting the covalent organic frameworks (COFs) materials on the environmental remediation of heavy metal ions. Water pollution caused by Cr3+ metal ions is of special concern for scientists and engineers. Notwithstanding all the former efforts made, it is surprising that very little is known about the interaction mechanisms between the hydrated Cr3+ metal ions and COF materials. In present context, density functional theory (DFT) method is used to elucidate geometric and electronic properties with the purpose of putting into theoretical perspective the application values and interaction mechanisms for COF materials on Cr3+ capture. The results showed that all the five selected Schiff-base COFs materials displayed good adsorption performance on Cr3+ removal while the phenazine-linked and imine-COFs possessed the most favorable adsorption capacity due to the optimal chemical units and frameworks. The hydration effect was found to play a two-side role in the adsorption process and interaction mechanisms, involving coordination, hydrogen bonds, as well as weak non-covalent interactions, have been illuminated to explain the observed different adsorption behaviors. This study provides a general guidance for the design and selection of efficient COF materials as high-capacity Cr3+ adsorbents.