Decontamination Of Heavy Metals Research Articles

Dual-functional natural rubber latex foam composites for solar-driven clean water production and heavy metal decontamination

Solar steam generation (SSG) offers a sustainable approach to fresh water production. Herein, a novel dual-functional natural rubber/carbon black composite foam evaporator is presented for a cost-efficient SSG system that both produces fresh water and eliminates heavy metals present in the water. The composite foam is produced using the Dunlop process, and in its optimized form, it absorbed >96 % of sunlight. The foam evaporator exhibited a thermal conductivity of 0.052 W/m⋅K, a water evaporation rate of 1.40 kg/m2/h, converted 83.38 % of light to heat under 1 sun irradiation, and showed outstanding stability. The technology required to produce this composite foam is already available to make large-scale production feasible, while the natural raw materials are abundant. On the basis of its performance qualities, the rubber foam composite appears to be an excellent candidate for application as a viable solar absorber for SSG to produce fresh, clean water for commercial purposes.

Investigation of regeneratable biopolymer-based aerogels for heavy metal decontamination from water: Quantum chemical analysis and experimental investigation

Heavy metals pose a significant threat to human health and ecological security due to their high toxicity, mobility, and persistence in the environment. Herein, the synthesis of a novel cellulose nanofiber-based aerogel using non-toxic biopolymers such as sodium alginate and polyglutamic acid to eradicate lead, zinc, and copper from water is described. The physical characterisation and the adsorption performance of the aerogels were evaluated in both monolithic and bead configurations. The study revealed superior adsorption performance for the aerogel beads compared to the monolithic configuration. The aerogel beads achieved a maximum adsorption capacity of 171.7 mg/g, 100.0 mg/g, and 142.0 mg/g for lead, zinc, and copper respectively. The aerogel beads exhibited a higher specific surface area compared to the monolithic aerogels. The presence of functional groups including carboxyl, amino, and hydroxyl groups on the aerogels likely facilitated the adsorption through coordinate bond formation and electrostatic interactions. Density Functional Theory calculations supported the role of oxygen and nitrogen containing groups on the aerogel in capturing heavy metal ions. The aerogels displayed a remarkable regeneration ability and were reused 20 times, without any significant reduction in the adsorption performance indicating its potential as a sustainable adsorbent for heavy metals removal from water.

Diels-Alder clickable furan-thiosemicarbazide cellulose for selective ruthenium (III) imprinting

Developing an efficient adsorbent for Ru3+ ions in wastewater is crucial for both environmental protection and resource recovery. This study introduces a novel approach using cellulose-based adsorbents, specifically modified with furan-thiosemicarbazide (FTC), to enhance their selectivity for Ru3+ ions. By cross-linking the Ru3+/FTC-modified cellulose (FTC-CE) complex with a bis(maleimido)ethane (BME) cross-linker, we created a Ru3+ ion-imprinted sorbent (Ru-II-CE) that exhibits a strong affinity and selectivity for Ru3+ ions. The synthesis process was thoroughly characterized using NMR and FTIR spectroscopy, while the surface morphology of the sorbent particles was examined with scanning electron microscopy. The Ru-II-CE sorbent demonstrated exceptional selectivity for Ru3+ among competing metal cations, achieving optimal adsorption at a pH of 5. Its adsorption capacity was notably high at 215 mg/g, fitting well with the Langmuir isotherm model, and it followed pseudo-second-order kinetics. This study highlights the potential of FTC-CE for targeted Ru3+ removal from wastewater, offering a promising solution for heavy metal decontamination.

Heavy metal decontamination by ion exchange polymers for water purification: counterintuitive cation removal by an anion exchange polymer

Ion exchange polymers were used for mercury and lead ions removal in water. The heavy metal ion concentration was analyzed by two independent methods: inductively coupled plasma–optical emission spectroscopy (ICP-OES) and gravimetry. The studied cation exchange polymer (CEP) was sulfonated poly(ether ether ketone) (SPEEK), and the anion exchange polymer (AEP) was poly(sulfone trimethylammonium) chloride (PSU-TMA). The removal capacity was connected with the ion exchange capacity (IEC) equal to 1.6 meq/g for both polymers. The concentration ranges were 0.15–0.006 mM for Hg2+ and 10.8–1.0 mM for Pb2+. SPEEK achieved 100% removal efficiency for mercury and lead if the concentration was below the maximum sorption capacity (Qmax), which was about 210 mg/g for Pb2+ with SPEEK. For PSU-TMA, the surprising removal efficiency of 100% for Hg2+, which seemed incompatible with ion exchange, was related to the formation of very stable complex anions that can be sorbed by an AEP. Langmuir adsorption theory was applied for the thermodynamic description of lead removal by SPEEK. A second-order law was effective to describe the kinetics of the process.

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

Treatment of heavy metal ions from simulated water using adsorption process via modified iron magnetic nanocomposite

Heavy metals are considered hazardous elements because they are not biodegradable in the environment. Exposure to heavy metals leads to serious problems that affect human health and the aquatic environment. Removal of heavy metal ions from simulated water was employed for chitosan/iron nanocomposites (C-Fe2O3NPs). C-Fe2O3 was prepared from chitosan solution and iron salt. The characterization of C-Fe2O3 was carried out using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF), and X-ray diffractometry (XRD). To determine the morphological structure, functional groups, and physicochemical properties. Determination of the optimum operating experimental conditions that result in the highest efficiency for heavy metal ions was investigated, such as contact duration (0–60 min), concentration (0.5, 1, 2, 3, and 5 mg/L), and adsorbent dose (0.1–0.5 g/L). Subsequently, the application of modified C-Fe2O3 in batch system for the elimination of Cu, Cr, Pb, Zn, and Se from simulated water was carried out. The results showed that EDX displayed the existence of iron, indicating the presence of iron nanoparticles. Also, the XRD and XRF showed the presence of iron oxide in the crystalline phase. The optimal conditions of the breakthrough curve, such as column height, flow rate, and contact time, were also examined. The results showed that the optimal conditions in the column system were a height of 10 cm, a flow rate of 5 mL/min, and a concentration of 3 mg/L. The kinetic information obtained was best modeled with the pseudo second-order model, and the experimental results fit the Langmuir model. High removal rates for Cu, Cr, Zn, Se, and Pb reached 99.8%, 93.8%, 98.8%, 99.8%, and 97.8%, respectively were achieved. The regeneration study indicated the good shelf life of iron magnetic NPs, which was 4.2%. In conclusion, C-Fe2O3 NPs are a potential adsorbent for heavy metal decontamination from water.

Phytoremediation as a green and sustainable prospective method for heavy metal contamination: a review

Cleaning up heavy metal-polluted soil through various mechanisms of phytoremediation is an economical, aesthetically beautiful, and environmentally responsible alternative to chemical or physicochemical approaches for heavy metal decontamination.

Multicomponent Reactions Promoted by Ecocatalyst from Metal Hyperaccumulating Plant Pluchea sagittalis

Phytoremediation has been considered a sustainable environmental technology for heavy metals decontamination. In this work, we evaluated the metal contents by inductively coupled plasma optical emission spectrometry (ICP-OES) of three plant species collected in a mine in the Brazilian Amazonia area. Based on this analysis, Pluchea sagitallis leaves were selected to prepare metallic ecocatalysts. The leaf ashes and the obtained ecocatalysts were characterized by ICP-OES, X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2-physisorption measurements. Moreover, they were evaluated in the Biginelli and Hantzsch multicomponent reactions, furnishing the corresponding 3,4-dihydropyrimidin-2-(1H)-ones and 1,4-dihydropyridines with good to excellent yields. The best ecocatalyst was easily recovered and recycled in up to six reactions without a significant decrease in its performance.

Multifunctional Biotemplated Micromotors for In Situ Decontamination of Antibiotics and Heavy Metals in Soil and Groundwater.

The ubiquitous pollution by antibiotics and heavy metal ions has posed great threats to human health and the ecological environment. Therefore, we developed a self-propelled tubular micromotor based on natural fibers as an active heterogeneous catalyst for antibiotic degradation and adsorbent for heavy metal ions in soil/water. The prepared micromotors can move in the presence of hydrogen peroxide (H2O2) through a bubble recoil mechanism. The MnO2 NPs and MnFe2O4 NPs loaded on the hollow fibers not only enabled self-driven motion and magnetic control but also served as activators of peroxymononsulfate (PMS) and H2O2 to produce active free radicals SO4•- and •OH. Benefiting from the self-propulsion and bubble generation, the micromotors can effectively overcome the disadvantage of low diffusivity of traditional heterogeneous catalysts, achieving the degradation of more than 90% TC in soil within 30 min. Meanwhile, due to the large specific surface area, abundant active sites, and strong negative zeta potential, the micromotors can effectively adsorb heavy metal ions in the water environment. In 120 min, self-propelled micromotors removed more than 94% of lead ions, an increase of 47% compared to static micromotors, illustrating the advantages of on-the-fly capture. The prepared micromotors with excellent catalytic performance and adsorption capacity can simultaneously degrade antibiotics and adsorb heavy metal ions. Moreover, the magnetic response enabled the micromotors to be effectively separated from the system after completion of the task, avoiding the problem of secondary pollution. Overall, the proposed micromotors provide a new approach to the utilization of natural materials in environmental applications.

Biochar supported metallo-inorganic nanocomposite: A green approach for decontamination of heavy metals from water.

Heavy metal contamination of water has become a global environmental burden, which has stirred up agitation worldwide. Fabrication of adsorbents utilizing either low cost, environment friendly materials or waste products can be helpful in remediating environmental pollution. The current study evolved around the synthesis of nanocomposites derived from such raw precursors like spent tea waste biochar, hydroxyapatite, and clays. In this context, two nanocomposites, namely manganese ferrite doped hydroxyapatite/kaolinite/biochar (TK-NC) and manganese ferrite doped hydroxyapatite/vermiculite/biochar (TV-NC), were synthesized followed by their employment for decontamination of heavy metals from aqueous media. TK-NC and TV-NC exhibited the crystallite sizes in the range of 2.55-5.94 nm as obtained by Debye Scherrer Equation and Williamsons-Hall equation The fabricated nanocomposites were characterized using FT-IR, SEM-EDX, and powder XRD. Batch adsorption studies were performed, and influence of different adsorption parameters (contact time, reaction temperature, solution pH, adsorbent dose, and initial adsorbate concentration) on metal adsorption was examined. Thermodynamic studies revealed that the adsorption of Cr(VI), Ni(II) and Cu(II) on TK-NC and TV-NC was endothermic (+ΔH°) and indicates disorderness (+ΔS°) at the solid-liquid interface owing to the strong affinity of metal ions with adsorbent. The heavy metal uptake selectivity followed the following decreasing order; Cr(VI) > Cu(II) > Ni(II) by both nanocomposites, with adsorption capacities falling in the range of 204.68-343.05 mg g-1. Several adsorption kinetic and isotherm models were applied to experimentally calculated data, which suggest favorable adsorption of Cr(VI), Ni(II) and Cu(II) by TK-NC and TV-NC from the system while obeying general-order kinetics and R-P adsorption model, conferring the transition in adsorption kinetics order and involvement of multiple adsorption process.

Radiation synthesized carboxyl-functionalized covalent organic framework adsorbent for efficient heavy metal decontamination

Carboxyl groups exhibit great potential in the field of heavy metal decontamination due to their good coordination ability. In this work, acrylic acid was grafted onto covalent organic framework (COF) by using a γ-ray radiation grafting approach. A carboxyl-functionalized adsorbent designated AA-TbDa-COF with high performance for multiple heavy metal removal was obtained. Infrared spectroscopy and thermogravimetric analysis proved the successful carboxyl modification. The porous nanofiber morphology and high accessibility of carboxyl functional groups give the resultant AA-TbDa-COF ultra-fast adsorption kinetics. The capacity for Pb2+, Cd2+ and Cu2+ decontamination was 127.9, 60.6 and 39.8 mg/g, respectively. The preparation of functional COFs by radiation method is extended to the field of heavy metal treatment, proving the great potential of radiation-prepared materials in environmental governance.

Free nitrous acid-assisted asymmetrical alternating current electrochemistry (FNA-AACE) for multi-heavy metals decontamination in waste activated sludge

Heavy metal contamination of waste activated sludge (WAS) is a key factor limiting the land application of sludge for nutrients recovery. This study proposes a novel free nitrous acid (FNA)-assisted asymmetrical alternating current electrochemistry (FNA-AACE) process to achieve high-efficiency decontamination of multi-heavy metals (Cd, Pb, and Fe) in WAS. The optimal operating conditions, the heavy metal removal performance of FNA-AACE, and the related mechanisms for maintaining the high performance were systematically investigated. During the FNA-AACE process, FNA treatment was optimal with an exposure time of 13 h at a pH of 2.9 and an FNA concentration of 0.6 mg/g TSS. Then the sludge was washed with EDTA in a recirculating leaching system under asymmetrical alternating current electrochemistry (AACE). The 6-h working and the following electrode cleaning were defined as a working circle of AACE. After three cycles of working-cleaning periods in AACE treatment, the cumulative removal efficiency of the toxic metals Cd and Pb reached over 97% and 93%, respectively, whilst that of Fe was greater than 65%. This surpasses most previously reported efficiencies and possesses a shorter treatment duration and sustainable EDTA circulation. The mechanism analysis suggested that FNA pretreatment provoked the migration of heavy metals for leaching enhancement, as well as reduced the demand for EDTA eluent concentration and increased conductivity, which can improve the AACE efficiency. Meanwhile, the AACE process absorbed the anionic chelates of heavy metals and reduced them to zero-valent particles on the electrode, regenerating the EDTA eluent and maintaining its high extraction efficiency for heavy metals. In addition, FNA-AACE could provide different electric field operation modes, allowing it to have flexibility for the real application processes. This proposed process is expected to be coupled with anaerobic digestion in wastewater treatment plants (WWTPs) for high efficiency of heavy metal decontamination, sludge reduction, and resource/energy recovery.

Antibacterial and Photocatalytic Activities of LDH-Based Sorbents of Different Compositions.

Layered double hydroxides (LDHs) play a fundamental role in the processes for the abatement of pollutants in water, with reference to heavy metal decontamination. The research on the topic is multiobjective target oriented, aiming at combining environmental remediation with the possibility of reusing a sorbent as many times as possible, turning it into a renewable resource. In this study, the antibacterial and catalytic properties of a ZnAl-SO4 LDH and its resulting product after being subjected to a Cr(VI) remediation process are compared. Both solid substrates have also been tested after undergoing a thermal annealing process. The sorbent (previously described and tested for remediation) has been investigated for its antibacterial activity in view of further surgery and drug delivery applications. Finally, its photocatalytic properties have been experimentally tested in the degradation of a model pollutant, i.e., Methyl Orange (MO), under solar-simulated light. Identifying the best recycling strategy for these materials requires an accurate knowledge of their physicochemical properties. The results show that both the antimicrobial activity and the photocatalytic performance may considerably improve after thermal annealing.

Heavy Metal Contamination in the Aquatic Ecosystem: Toxicity and Its Remediation Using Eco-Friendly Approaches

Urbanization and industrialization are responsible for environmental contamination in the air, water, and soil. These activities also generate large amounts of heavy metal ions in the environment, and these contaminants cause various types of health issues in humans and other animals. Hexavalent chromium, lead, and cadmium are toxic heavy metal ions that come into the environment through several industrial processes, such as tanning, electroplating, coal mining, agricultural activities, the steel industry, and chrome plating. Several physical and chemical methods are generally used for the heavy metal decontamination of wastewater. These methods have some disadvantages, including the generation of secondary toxic sludge and high operational costs. Hence, there is a need to develop a cost-effective and eco-friendly method for the removal of heavy metal ions from polluted areas. Biological methods are generally considered eco-friendly and cost-effective. This review focuses on heavy metal contamination, its toxicity, and eco-friendly approaches for the removal of heavy metals from contaminated sites.

Decoration of polystyrene with nanoparticles of cobalt hydroxide as new composites for the removal of Fe(iii) and methylene blue from industrial wastewater.

Effluent water from different industries is considered one of the most serious environmental pollutants due to its non-safe disposal. Therefore, proper treatment methods for such wastewater are strongly stimulated for its potential reuse in industries or agriculture. This study introduces a composite fabricated via doping of polystyrene with nanoparticles of cobalt hydroxide as a novel adsorbent for dye and heavy metal decontamination from wastewater. The adsorbent fabrication involves the preparation of polystyrene via high-internal phase emulation (HIPE) polymerization followed by its intercalation with particles of alkali cobalt. The chemical composition and structural properties of the synthesized composite were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). Moreover, scanning electron microscopy (SEM) and N2 adsorption-desorption surface area analysis were performed to identify the surface and morphological characteristics of the composite. Then, the ability of this structure toward the removal of methylene blue dye (MB) and heavy metal (iron iii) species from waste aqueous solutions was investigated. Successful elimination for both MB and Fe(iii) was achieved by the presented composite. Elevated adsorption capacities of 75.2 and 112.3 mg g-1, toward MB and Fe(iii) respectively, were detected for the presented polymer-metal hydroxide composite. The increased values of the composite are attributed to the presence of both organic and inorganic functional groups within its structure. Kinetic and isotherm studies for the removal of both cationic species revealed that adsorption processes fit the pseudo-second-order kinetic model and Langmuir isotherm model. Additionally, thermodynamics measurements indicated that the adsorption process of methylene blue and Fe ions is feasible, spontaneous, physisorption, and endothermic.

Efficient Pb(II) adsorption in aqueous solution by hierarchical 3D/2D TiO2/CNNS nanocomposite

A multifunctional nanomaterial for contaminants’ removal and solar fuel production is designed, for solving environmental and energy problems. In this research, hierarchical three-dimensional (3D)TiO2 doped with porous graphite-like two-dimensional (2D) carbon nitride (g-C3N4) nanosheets (TiO2/CNNS) composite was fabricated by solid interfacial reaction through a facile acid hydrothermal route. Interestingly, the produced catalyst showed extraordinarily selective adsorption towards Pb (II) metal ions through strong electrostatic attraction mainly due to the enlarged surface areas and pore volume, besides increased adsorption/active sites. The obtained batch mode adsorption measurements reveal a high removal efficiency of give 378 mg.g−1 in a very short period of time of 7 min. This study highlights the importance of designing 3D/2D multifunctional g-C3N4-based photocatalysts for environmental heavy metals decontamination.

Phytoremediation: A Novel Approach of Bast Fiber Plants (Hemp, Kenaf, Jute and Flax) for Heavy Metals Decontamination in Soil-Review.

Heavy metal pollution in the environment is a major concern for humans as it is non-biodegradable and can have a lot of effects on the environment, humans as well as plants. At present, a solution to this problem is suggested in terms of a new, innovative and eco-friendly technology known as phytoremediation. Bast fiber plants are typically non-edible crops that have a short life cycle. It is one of the significant crops that has attracted interest for many industrial uses because of its constant fiber supply and ease of maintenance. Due to its low maintenance requirements with minimum economic investment, bast fiber plants have been widely used in phytoremediation. Nevertheless, these plants have the ability to extract metals from the soil through their deep roots, combined with their commercial prospects, making them an ideal candidate as a profit-yielding crop for phytoremediation purposes. Therefore, a comprehensive review is needed for a better understanding of the morphology and phytoremediation mechanism of four commonly bast fiber plants, such as hemp (Cannabis sativa), kenaf (Hibiscus cannabinus), jute (Corchorus olitorius) and Flax (Linum usitatissimum). This review article summarizes the existing research on the phytoremediation potential of these plants grown in different toxic pollutants such as Lead (Pb), Cadmium (Cd) and Zinc (Zn). This work also discusses several aids including natural and chemical amendments to improve phytoremediation. The role of these amendments in the bioavailability of contaminants, their uptake, translocation and bioaccumulation, as well as their effect on plant growth and development, has been highlighted in this paper. This paper helps in identifying, comparing and addressing the recent achievements of bast fiber plants for the phytoremediation of heavy metals in contaminated soil.

Clean hydrometallurgical route for highly efficient decontamination and recycling of multiple heavy metals from hazardous Pb smelting residues: Multi-objective leaching optimization, adsorption, and risk assessment

Huge amounts of Pb smelting residues were generally stored in landfills or unprocessed worldwide, and thus demand novel strategies to implement clean production. In this paper, we proposed a clean, efficient and economical hydrometallurgical route to recycle the toxic heavy metals including Zn, Pb and Cd from the Pb residue by the biodegradable low-molecular-weight organic acids (LMWOAs) and the cation exchange resin (CER, 001 × 7). The multi-objective leaching process of the three metals was optimized by combining saturated D-optimal design with desirability function simultaneously. The recovery rates of Zn, Pb and Cd were 88.72–96.36, 65.40–85.31 and 92.63–97.10% at the optimal conditions of 0.73–1.00 mol L−1 agent concentrations, 2.0–3.3 solution pH values and 71–120 min durations, respectively. Adsorption with CER from the resulting leachates recycled over 91.48% of the metal ions. The treated residues were almost completely decontaminated. Therefore, this research filled the gap of clean production route of hydrometallurgical recycling for metal resources from the low-grade slag.

Green MoS2 nanosheets as a promising material for decontamination of hexavalent chromium, pharmaceuticals, and microbial pathogen disinfection: spectroscopic study

Photoreduction of chromium hexavalent ions (Cr6+) from the aquatic environment is urgently needed due to its impairing effect on human health. Adsorption, photoreduction, and desorption of reduced trivalent chromium (Cr3+) at the photocatalyst surface are all significant factors for determining photocatalytic reduction efficiency. Herein, we report a facile, template-free hydrothermal approach to fabricate green and homogeneous mixed-phase (1 T/2H) molybdenum disulfide (MoS2) nanosheets for highly efficient removal of Cr6+ ions and pharmaceuticals from wastewater. The nanostructure and morphology of the obtained (1 T/2H) MoS2 are investigated; the calculated crystallite size of the (2H/1 T) MoS2 nanosheets is found to be 1.7 nm. The presence of surface functional groups adsorption, and photoreduction processes is confirmed by spectroscopic studies using Fourier transform infrared (FTIR) spectra. Additionally, Raman spectra confirmed the formation of 1 T/2H mixed-phase MoS2 which illustrates its crystal phases, structure, and chemical composition. Moreover, the point-of-zero charge analysis revealed the positively charged surface in the acid system. The obtained results revealed the non-toxicity of MoS2 nanosheets at doses lower than 1000 ppm. The results reveal that the (1 T/2H) MoS2 exhibited impressive reduction performance for Cr6+; the reduction efficiency of chromium Cr6+ is 100% under simulated sunlight, 90 min at pH (3). Further spectroscopic study results confirm the importance of the adsorption step in Cr6+ ions photoreduction. Different pharmaceuticals are also completely degraded over (1 T/2H) MoS2 nanosheets. Interestingly, complete removals of E. coli O157:H7, Listeria monocytogenes, and Candida albicans were observed at a dose of MoS2 nanosheets of 250 ppm after a contact time of 30, 30, and 45 min, respectively. The results of the current work could lead to a rational design of high-performance nanosheets for the efficient decontamination of heavy metals, pharmaceuticals, and pathogens from aquatic environments.Graphical abstract

Hexavalent chromium elimination from wastewater by integrated micro-electrolysis composites synthesized from red mud and rice straw via a facile one-pot method

The widely spread chromium (Cr) contamination is rising environmental concerns, while the reutilization of agro-industrial by-products are also urgently demanded due to their potential risks. In this study, we prepared the integrated micro-electrolysis composites (IMC) through a facile one-pot method with red mud and rice straw. The effects of components relatively mass ratios as well as pyrolysis temperature were analyzed. The XRD, XPS, SEM, FTIR, and various techniques proved the IMC was successfully synthesized, which was also used to analyze the reaction mechanisms. In this study, the dosage of IMC, pH, adsorption time, and temperature of adsorption processes were explored, in the adsorption experiment of Cr(VI), dosage of IMC was 2 g/L (pH 6, 25 °C, and 200 rpm) for isothermal, while the concentration and contact time were also varied. According to the batch experiments, IMC exhibited acceptable removal capacity (190.6 mg/g) on Cr(VI) and the efficiency reached 97.74%. The removal mechanisms of adsorbed Cr(VI) were mainly elaborated as chemical reduction, complexation, co-precipitation, and physical adherence. All these results shed light on the facile preparation and agro-industrial by-products recycled as engineering materials for the heavy metals decontamination in wastewater.