Adsorbent For Removal Of Heavy Metals Research Articles

Role of nanocomposites and nano adsorbents for heavy metals removal and dyes. An overview

Water scarcity and wastewater treatment are major concerns due to increased urbanization, industrialization, and anthropogenic practices. Various toxic heavy metals, dyes, pollutants, and chemicals are a matter of concern as they have severe environmental and ecological damage and health effects. Various advancements are being introduced in the field of adsorption using nano adsorbents and composites to deal with wastewater treatment problems. Nanocomposites are intelligent to eliminate bacteria, viruses, and inorganic and organic pollutants from wastewater due to precise binding action (chelation, absorption, ion exchange). Nanocomposite materials, such as metal nanocomposite, metal oxide nanocomposite, carbon nanocomposite, polymer nanocomposite, and membrane nanocomposite, are active in water purification. Nanoparticles (N.P.s) are important for remediation because of their large surface area, size, reactivity, and active sites. For high adsorption of pollutants, N.P.s were treated by increasing the electron density and surface area and adding functional groups. They are more capable of eliminating hazardous organic-inorganic pollutants, pathogens, and heavy metals from wastewater. This nanotechnology treatment technique has no hazardous by-products; these techniques have various regenerative efficiencies. Among various treatment methods, the adsorption process is considered one of the most highly effective treatments of heavy metals, and the functionalization of adsorbents can fully enhance the adsorption process. Therefore, four adsorbent sources are highlighted: polymeric, natural mineral, industrial by-product, and carbon nanomaterial adsorbent. The major purpose of this review is to gather up-to-date information on research and development on various adsorbents in the treatment of heavy metal and dyes from water by emphasizing the adsorption capability, the effect of pH, isotherm and kinetic model, removal efficiency, and the contact of time of every adsorbent.

From agricultural wastes to advanced materials for environmental applications: Rice husk-derived adsorbents for heavy metals removal from wastewater

Agroindustry annually generates enormous amounts of residues, and their re-utilization is a convenient approach to mitigate environmental pollution and increase energy savings. Rice husk (RH) is one of the most widely available agricultural wastes in many countries of the world. RH and its ashes are often used directly for manufacturing and synthesizing new materials with added-value features. In this work, the preparation of composite materials for wastewater treatment has been explored by producing and testing mesoporous iron-oxide/RH composites for heavy metal adsorption. The composites were fully characterized and their application to the removal of Pb2+ and Cu2+ ions from model aqueous solutions at different pH values was tested to evaluate their adsorption performances and select those materials more suited for realistic applications. Our results indicated that the composite materials exhibited higher metal adsorption capacities than the pristine carbonized RH and the iron components, highlighting a synergism between the carbonized RH and iron-oxide phases.

Synthesis and characterization of thiazolidinone -functionalized MCM-41 and kaolinite nanocomposites as the powerful and new adsorbents for heavy metal removal: process optimization using RSM-CCD

Synthesis and characterization of thiazolidinone -functionalized MCM-41 and kaolinite nanocomposites as the powerful and new adsorbents for heavy metal removal: process optimization using RSM-CCD

Investigation of the potential of pomegranate peel as a treatment option for heavy metal contaminated wastewater: Experimental and modeling approaches

Heavy metals can cause serious environmental and human health problems, and their removal from wastewater is critical to protect our planet and communities. This study investigated the ability of crushed pomegranate peel to remove mercury and cadmium ions from contaminated water as a function of different experimental parameters. The experimental results showed that the pH of the solution influenced the adsorptive removal of heavy metals, with the best performance observed at pH 4.8. Optimization studies and process balance modeling were performed to optimize the process for commercial use. The performance of pomegranate peel was compared with that of other materials, and the highest adsorption capacities for both cadmium (Ca (II)) and mercury (Hg (II)) ions were observed to be 89.59 and 42.125 mg/g, respectively. The results were interpreted using the Langmuir model, which provided the best fit to describe the behavior of the process.

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.

Exploring biosynthesis strategies to boost the yield of exopolysaccharide-protein blend from Bacillus arachidis SY8(T), an isolated native strain, as a potent adsorbent for heavy metals removal

This investigation centers on the synthesis of a polysaccharide-protein blend produced by an isolated native strain (99.12 % phylogenetic affinity with Bacillus arachidis SY8(T)). The primary objective was to investigate the production of extracellular polymeric substances (EPS) under diverse stress conditions, encompassing exposure to heavy metal ions, salt, and toxic agents. Additionally, the impact of environmental parameters, namely pH, inoculation percentage, and time, on the production was investigated. Subsequently, the study examined the biosorption potential of the EPS produced for Pb(II), Cu(II), and Mn(II). The EPS obtained was thoroughly characterized via various tests. Rheological evaluations of an EPS solution (2 wt%) confirmed its pseudo-plastic and non-Newtonian fluid properties, while TGA analysis demonstrated its thermal stability up to 600 °C. Additional analyses, including GPC, FTIR, and H-NMR, provide further insights into the produced EPS. The best conditions for EPS production are determined: 5 % NaCl salt, serving as an effective stress inducer, and 37 °C, pH 6, with a 5 % inoculation, over 96 h. EPS demonstrates remarkable removal efficiencies of 99.9, 99.4 and 78.9 % for Pb(II), Cu(II), and Mn(II), respectively. These findings highlight the potential of EPS as an effective agent for removing heavy metal ions.

Optimizing enhanced heavy metal detoxification by novel hybrid fungal hyphae-nano-biocomposite functionalized with graphene oxide: Unravelling process parameters & adsorption modelling

Heavy metal pollution poses significant environmental and health risks, demanding efficient novel remediation strategies. This paper presents a fungal hyphae-based nano-biocomposite integrated with graphene oxide (FHGO) for the efficient removal of heavy metals from aqueous solutions. The successful formation of nanoparticles was investigated by morphological characterization using Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron microscopy (SEM) & X-ray diffraction (XRD). Through comprehensive exploration of process parameters, including pH, initial concentration, and contact time, the nano-biocomposite demonstrated exceptional removal efficiencies exceeding 90% for both heavy metals i.e. chromium (Cr6+) & nickel (Ni2+). The optimum pH conditions for Cr (VI) removal was 4,whereas it was 9 for Ni (II) removal. The equilibrium data were well-fitted to Langmuir isotherm models, suggesting monolayer adsorption onto a homogeneous surface with adsorption capacities of 38.89 mg/g & 42.88 mg/g for Ni (II) & Cr (VI), respectively, with value of R2=0.997. Additionally, biocompatibility assessments via (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) MTT assays on Henrietta Lacks (HeLa) cell line cultures revealed a low IC50 value of FHGO nano-biocomposite, affirming the efficiency of the composite for biomedical applications. Furthermore, seed germination assays indicated comparatively minimal hindrance to plant growth in the treated sample, highlighting the composite's potential for environmental remediation without compromising plant health. These findings underscore the promising potential of the fungal hyphae-based nano-biocomposite with GO as an effective and environmentally safe adsorbent for heavy metal removal, with implications for sustainable environmental management and public health protection.

Cd2+ removal efficiency of activated carbon from Prosopis juliflora: Optimization of preparation parameters by the Box-Behnken Design of Response Surface Methodology

The study focuses on the preparation of activated carbon from Prosopis juliflora (PJAC) wood by pyrolysis and chemical activation. The objective is to assess its effectiveness as an adsorbent for synthesizing a composite adsorbent coating (CAC) for Cadmium (Cd2+) removal from aqueous solution. The effect of preparation factors related to Cd2+ removal efficiency was assessed. The Design of Experiments (DoE) for the adsorption of Cd2+ on the PJAC were done using the Box-Behnken Design (BBD) of the Response Surface Methodology (RSM) (Design Expert software version 11). The influence of impregnation ratio (IR), carbonization time (t), and carbonization temperature (T) on the Cd (II) percent (%) removal was evaluated. The response surface graphs in 3D were also generated for the response variable, and the higher R2 coefficient values were fitted into the polynomial quadric model. The results indicated that all the variable preparation factors were significant in the Cd2+ removal by PJAC with carbonization temperature being the most significant. At the optimum conditions i.e. impregnation ratio (1.8), carbonization temperature (595 °C) and carbonization time (174 min), the model predicted a 99.9 % Cd2+ removal efficiency while the adsorption experiment obtained a 96.7 % removal efficiency, respectively. Later, the morphological and chemical properties of the PJAC prepared with optimal parameters were analyzed using different characterization techniques including SBET, SEM-EDX, pHPZC, FTIR and XRD. The SEM images revealed a rough and porous morphological surface with an SBET of 600.4 m2/g and a near neutral pHPZC of 6.92. The XRD pattern indicated the crystalline nature of the prepared adsorbent. The pre and post adsorption FTIR spectrum of the PJAC demonstrated a distinct difference with the latter showing a reduction in peak intensity and height. These results underpin the potential of utilizing invasive plants like Prosopis Juliflora as adsorbents for heavy metal removal.

Production of Modified Zeolites from Rice Husk Ash for Removal of Cadmium from Aqueous Solution

In this study, ZSM-5 zeolite from rice hush ash (RHA) was synthesized and modified to assess the removal of cadmium from aqueous solution using standard methods. Both the synthesized and modified ZSM-5 were characterized using XRD, SEM TEM, FTIR and BET. Presence of silicate in the RHA was confirmed with XRF to contain 86.85% silicate. Batch experiments of the adsorption carried out with specific concentration of cadmium shows that both the synthesized and modified zeolites demonstrated 44% and 78% cadmium ions removal from the simulated solution respectively. The study concluded that synthesized and modified ZSM-5 zeolites are highly efficient adsorbent for heavy metal removal.

Evaluating the performance of cement-modified biochar adsorbent for Cu, Pb and Zn removal from urban stormwater

This research investigates the use of biochar modified with Ordinary Portland Cement (OPC) as an adsorbent for heavy metal removal and evaluates the impact of competing ions and nutrients on the adsorptive removal process. The cement-modified biochar composites, featuring functional groups from biochar and hydrated OPC, exhibited significantly enhanced adsorption capacities for Cu, Pb, and Zn, approximately 3.3, 2.4, and 6 times higher, respectively, compared to unmodified biochar upon introducing 1.5 % (v/v) OPC. The Langmuir monolayer adsorption model accurately described the adsorption data, with heavy metals binding to functional groups like CC and CO, CO3–2, silanols (Si-OH), siloxanes and calcium silicate hydrate. The cement-modified biochar composite exhibited notable adsorption capacities for Cu, Pb, and Zn at 28.82 mg/g, 38.76 mg/g and 26.53 mg/g, comparable to commercial activated carbons. There were negligible effects from NO3- on the removal of Cu, Pb and Zn, PO43- ions enhanced Pb removal, and NH4+ ions slightly reduced the removal of all three metals, while humic acid increased removal. The findings indicate that using OPC boosts heavy metal adsorption, and insights into the influence of competing ions and nutrients apprise strategies for using OPC-modified biochar in practical applications.

Facile Synthesis of Sodium Dodecyl Sulfate Intercalated Mg‐Al LDH and its Excellent Adsorption Performances for Cu2+ from Aqueous Solution

AbstractIn this study, the magnesium aluminum layered double hydroxide intercalated with sodium dodecyl sulfate (Mg‐Al S‐LDH) was synthesized by using a roasting–restoration method based on the Mg‐Al LDH precursor, and their effectiveness in removing Cu2+ from aqueous solutions was investigated. Detailed microstructural characterization of these adsorption materials involved employing X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms (N2 ad/desorption), and thermogravimetric‐differential thermal gravimetric analysis (TG‐DTG). The experimental results revealed that Mg‐Al S‐LDH displayed a plate‐like layered structure with a larger surface area and enhanced adsorption ability. Specifically, the maximum adsorption capacity, reaching 96.15 mg ⋅ g−1, was achieved at a temperature of 298 K, accompanied by a rapid adsorption rate. The adsorption kinetics adhered to the pseudo‐second‐order model, suggesting that chemisorption controlled the adsorption behavior. Furthermore, the adsorption of Cu2+ followed the Freundlich model, signifying a multi‐site adsorption mechanism onto the surface and layers of Mg‐Al S‐LDH. Thermodynamic investigations indicated that higher temperatures facilitated Cu2+ dissolution and strengthened the affinity with Mg‐Al S‐LDH, with a positive ΔHΘ value suggesting that the Cu2+ adsorption process was endothermic and temperature‐enhancing. Ion selectivity experiments demonstrated that Cd2+ and Pb2+ ions had a significant impact on Cu2+ adsorption, while the effects of Zn2+ and Fe2+ ions were less pronounced. The primary adsorption mechanisms of Cu2+ onto Mg‐Al S‐LDH encompassed precipitation, complexation on the surface and layers, and isomorphous substitution. This study sheds light on the promising potential of Mg‐Al S‐LDH as an effective adsorbent for heavy metal removal and provides valuable insights into its adsorption mechanisms and performance in different environmental conditions.

Investigation of adsorptive removal of heavy metals onto magnetic core–double shell nanoparticles: kinetic, isotherm, and thermodynamic study

The most perilous environmental hazards arise from the contamination of water by heavy metal ions, owing to the non-biodegradability of these metals, as well as their rapid dissemination throughout components of the environment via the food chain. Nano-based adsorbents have been used for the adsorption removal of many heavy metal cations, but separating and recycling them represent significant difficulties in processing. Magnetic core–double shell nanoparticles provide an attractive solution for processing issues, since they are stable and can be easily separated and recycled. Moreover, the shell thickness, composition, and porosity can be easily tuned. In this work, two samples consisting of magnetic core@TiO2@mesoSiO2 nanoparticles with two shell thicknesses (Mag-T-S-0.2 and Mag-T-S-0.4), along with a magnetic core@SiO2@TiO2 nanoparticle sample (Mag-S-T), were synthesized and characterized by TEM, XRD, magnetic strength measurement and zeta potential. TEM images show the developed core–double shell structure with double shell ranging from 60 to 73 nm. The XRD results indicate the impact of the outer shell on the diffraction pattern. The zeta potential shows that all samples had a negative charge at pH over 4. The magnetic character was suppressed after the formation of the double-shell coating; however, the magnetic core–double shell nanoparticles still had magnetization and could be separated when an external magnetic field was applied. The heavy metal adsorptive ability of Mag-T-S-0.2, Mag-T-S-0.4, and Mag-S-T samples was explored to investigate the effects of shell type and thickness along with kinetic, isotherm, and thermodynamic study. The investigated heavy metals included Cd(II), Ni(II), Mn(II), Pb(II), and Cu(II). The results indicate that, for Mag-T-S-0.2, the equilibrium state occurred after 15 min contact time, with adsorption capacity of 238, 230, 210.6, 181.8, and 245.8 mg/g for Cd(II), Ni(II), Mn(II), Pb(II), and Cu(II), respectively. For Mag-T-S-0.4, the equilibrium state occurred after 15 min contact time, with adsorption capacity of 241, 237.6, 173.8, 189.6, and 257.2 mg g−1, respectively. For Mag-S-T, the equilibrium state occurred after 25 min contact time, with adsorption capacity of 137.8, 131.4, 221, 189.6, and 149.4 mg g−1, respectively. When pseudo-first-order and pseudo-second-order kinetic models were applied to investigate the time interval adsorption data for Mag-T-S-0.2, Mag-T-S-0.4, and Mag-S-T samples, the second-order kinetic model was found to be more suitable for describing the process, indicating a fast adsorption mechanism. The adsorption data did not fit well with the Langmuir model, while they did fit well with the Freundlich model, suggesting heterogeneous material surfaces and multi-layer adsorption. Thermodynamic investigations confirmed the spontaneous nature of adsorptive removal, which helps to promote magnetic core@TiO2@mesoSiO2 and magnetic core@SiO2@TiO2 nanoparticles as effective adsorbents for wastewater treatment.

Cation Effect in Polysaccharide-Based Hydrogel Beads Produced for Europium Adsorption from Aqueous Solutions

In recent decades, renewable and biodegradable polysaccharide-based hydrogels have enjoyed wide applicability among them also as adsorbents for heavy metal removal from wastewaters. Herein we prepared hydrogel beads from iota and kappa carrageenans using a variety of salts as crosslinkers, that were tested for the first time in europium ion (Eu3+) sorption from an aqueous solution as representative lanthanide. The type of the salt, and especially the valance and the hydrated radius of the cation, were found to dictate hydrogel bead formation and structure and, therefore, the Eu3+ sorption yield. The results of ATR-FTIR, SEM and TGA analyses to characterize the iota carrageenan hydrogel beads that were prepared with alkali cations, before and after interaction with Eu3+, indicate that the adsorbent prepared with LiCl was much stiffer and more stable than those prepared with NaCl or KCl. The iota carrageenan beads that were prepared with LiCl were also reused 5 times while exhibiting high adsorption capacities.

ADSORTION POTENTIAL OF GARLIC, GINGER AND LEMON IN THE REMOVAL OF HEAVY METALS FROM AQUEOUS SOLUTIONS

This work was conducted to assess the efficiency of Garlic, Ginger and Lemon in the removal of some Heavy Metals from aqueous solution. Batch adsorption process was employed in the experiments. Different dosages (0.2, 0.4, 0.6, 0.8 and 1.0) g of the adsorbents and concentrations of the heavy metals (1000ppm, 800ppm, 600ppm, 400ppm, and 200ppm) were prepared and used. Flame Atomic Absorption Spectroscopic (FAAS) was used to determine the amount of heavy metal concentrations adsorbed at each stage of the experiment. Results obtained show that there was remarkable reduction of metal concentrations in the solutions. However, comparatively, the efficiency of garlic in absorbing the metals is greater than that of ginger and lemon at all conditions. Thus, results obtained suggest that Garlic, Ginger and Lemon could be promising adsorbents for heavy metal removal in aqueous solutions, but garlic has greater efficiency in adsorbing the metals particularly zinc and copper.

Wastewater Treatment Utilizing Industrial Waste Fly Ash as a Low-Cost Adsorbent for Heavy Metal Removal: Literature Review

Wastewater discharges from industrial processes typically include elevated concentrations of contaminants, which largely consist of potentially harmful chemicals such as heavy metals. These contaminants are characterized by their slow rate of decomposition. Hence, the removal of these metallic ions from effluents poses a challenge. Among different treatments, the adsorption approach has considerable potential due to its ability to effectively eliminate both soluble and insoluble pollutants from effluent, even at lower levels of concentration. Of various wastes, fly ash (FA) material has been the subject of attention because it is abundant, has favorable qualities, and contains a high percentage of minerals. This review investigates multiple facets, with a specific focus on the application of FA, an industrial byproduct, as an adsorbent in removing heavy metals. A comprehensive examination was conducted on a range of concerns pertaining to the pollution caused by metallic ions, including the underlying causes, levels of contamination, health implications of heavy metals, and removal methods. Multiple factors were found to affect the adsorption process. Of all the factors, the pH value considerably influences the elimination of heavy metals. An acidic pH range of 2.5–4.5 was found to be optimal for achieving the highest possible elimination of As(V), Cu(II), Hg(II), and Cr(VI). The latter elimination rate reached 89% at the optimal pH level. Most heavy metals’ adsorption isotherms conformed to the Langmuir or Freundlich models, while the pseudo-second-order kinetics provided a satisfactory match for their removal. Using a raw FA, adsorption capacities were achieved in the removal of metallic ions, Ni(II), Pb(II), and Cr(VI), that ranged from 14.0 to 23.9 mg g−1. Meanwhile, the FA-zeolite showed a remarkable capacity to adsorb ions Mn(II), Ni(II), Cd(II), Cu(II), and Pb(II), with values ranging from about 31 to 66 mg g−1. The cost analysis showed that the treatment of FA is economically advantageous and may result in significant cost reductions in comparison to commercial adsorbents. In summary, FA is an inexpensive waste material with potential for water treatment applications and several other purposes due to its excellent chemical and mineralogical composition.

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.