Adsorption Process Of Metal Ions Research Articles

Development and characterization of novel CS-ZnO-Alg polyelectrolyte complex for enhanced removal of Cd(II), Cu(II), and Ni(II) from simulated paint industrial wastewater

In this study, we developed and characterized a novel chitosan-alginate-based polyelectrolyte complex impregnated with zinc oxide nanoparticles (CS-ZnO-Alg PEC) for the enhanced removal of Cd(II), Cu(II), and Ni(II) from simulated paint industrial wastewater. The prepared PEC was characterized by X-ray Diffraction (XRD), Fourier-Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS), X-ray Photoelectron Spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and Thermogravimetric analysis/Differential Thermal Analysis (TGA/DTA). The equilibrium data for said metal ions was best appropriated by Freundlich isotherm with maximum adsorption capacity of 217.72 mg/g for Cd(II), 130.41 mg/g Cu(II), and 159.06 mg/g for Ni(II), illustrating the multilayer adsorption of metal ions on the heterogeneous surface sites of the adsorbent. The kinetics of all three metal ions adsorption process onto discussed PEC was consistent with pseudo-second-order model. The thermodynamics results illustrate exothermic and spontaneous processes for Cd(II) (ΔH° = −3.57 KJ/mol, ΔS° = 0.009 KJ/mol*K, ΔG° = −6.42 to −6.61 KJ/mol) and Cu(II) (ΔH° = −3.32 KJ/mol, ΔS° = 0.006 KJ/mol*K, ΔG° = −5.25 to −5.37 KJ/mol), and spontaneous but less favorable adsorption for Ni(II) (ΔH° = −0.82 KJ/mol, ΔS° = −0.001 KJ/mol*K, ΔG° = −0.39 to −0.36 KJ/mol). Notably, the PEC could be easily recycled and regenerated, maintaining adsorption efficiency after five cycles. Overall, the CS-ZnO-Alg PEC, due to its amphoteric nature, high adsorption efficiency, cost-effectiveness, excellent recyclability, and biodegradability, could be a promising adsorbent for paint industrial wastewater.

Statistical physics investigation on the simultaneous adsorption mechanism of Cd2+ and Pb2+ on amino functionalized activated carbon derived from coal gasification fine slag

In this study, a novel surface amino-functionalized activated carbon (T-AC) was synthesized from coal gasification fine slag (CGFS) and used as an adsorbent for heavy metal ions. T-AC exhibits excellent adsorption capacity for Cd2+ and Pb2+. The adsorption process of Cd2+ and Pb2+ onto T-AC was found to be spontaneous. The dominant adsorption process was chemisorption, primarily involving chelation and covalent bonding. In binary systems, as the initial concentration increases, the independent adsorption effect of Pb2+ and Cd2+ gradually becomes a competitive adsorption effect. Statistical physical models revealed that the adsorption of T-AC for Cd2+ and Pb2+ in single systems followed a multi-molecular adsorption process, whereas in binary systems, it involved a multi-anchorage process. The adsorption capacity was primarily influenced by the number of ions attached to the receptor sites and the density of the adsorbent receptor sites. Moreover, elevating temperature enhanced the thermal movement of heavy metal ions within the pore structure of the adsorbent, reducing their tendency to aggregate at the active sites. This work provides insights into the microscopic-level adsorption process of heavy metal ions by carbon-based materials and contributed to understand of the adsorption behavior.

Sequestration of zirconium and hafnium content using magnetic cellulose/chitosan nanocomposites from waste effluents

New Magnetic nanocomposites containing biological polymer (i.e. chitosan and cellulose) as reinforcers were synthesized. Successful fabrication of the magnetic cellulose-chitosan (MCCh) nanocomposites with norvaline (MCCh-N) and 8-hydroxyquinoline (MCCh-8H), respectively were achieved and investigated as a zirconium and hafnium ions adsorbent in aquatic media. The felicitous synthesis was confirmed using FTIR, TGA, TEM, DLS, XRD, SEM-EDX, and BET analyses. The nanocomposites (MCCh-N and MCCh-8H) performance was evaluated under different conditions of adsorbent dose (0.01–0.1 g), Zr(IV) and Hf(IV) initial concentration (100–500 mg/L), pH (1.0–2.5), temperature (~25–55 °C), and time (~10–120 min). The adsorption process of both metal ions on the prepared nanocomposites was modeled using Langmuir, Freundlich, Temkin, and D-R models. The elimination of Zr(IV) and Hf(IV) by MCCh-N and MCCh-8H followed a pseudo-second-order kinetic model (R2 = 0.998, 0.997 and 0.998, 0.999), respectively. Furthermore, kinetic, thermodynamic, and reusability studies were conducted to evaluate the behavior and adsorption mechanism of Zr(IV) and Hf(IV) on the surface of MCCh-N and MCCh-8H nanocomposite.All in all, the high removal capturing and recovering zirconium and hafnium ions from laboratory wastewater and waste solution resulting from the leaching process of the Abu Rusheid concentrate sample make MCCh-N and MCCh-8H potential adsorbents for in situ treatment of zirconium and hafnium ions-containing aqueous solutions.

Removal of Pb (II) and Zn (II) in the mineral beneficiation wastewater by using cross-linked carboxymethyl starch-g-methacrylic acid as an effective flocculant.

The cross-linked carboxymethyl starch-g-methacrylic acid (CCMS-g-MAA) was prepared by using grafting and micro-cross-linking in the one-pot preparation process. CCMS-g-MAA presented high removal capacity of Pb (II) of 57.13 mg/g at pH = 4 and high removal capacity of Zn (II) of 51.41 mg/g at pH = 5 by using a sample dosage of 0.68 g/L. Characterization results of FTIR, TG, and XRD illustrate that methacrylic acid and sodium tri-metaphosphate were successfully introduced into the structure of carboxymethyl starch. SEM characterization presented that the sample particles were amorphous aggregates with surface voids, which was favorable for the adsorption of heavy metal ions from wastewater. Adsorption isotherm results indicated that Freundlich equation could be better used to describe the adsorption process of metal ions on CCMS-g-MAA. The adsorption kinetic results indicated that the pseudo-second-order model is more suitable to describe this removal process. XPS results indicated that metal ions interacted with functional groups on the surface of flocculant, especially carboxyl groups. The removal process may be purposed that metal ions were adsorbed by porous material, and then combined with surface functional groups of the flocculant via electrostatic interaction, chelation or ion exchange. Subsequently, metal ions were separated from the wastewater with flocs precipitated in the bottom of solution via bridging and patching. The obtained results illustrated that CCMS-g-MAA was an effective material for the treatment of wastewater containing polymetallic ions besides mineral beneficiation wastewater supported by its excellent regeneration.

Quantum adsorption mechanism of gelatin cellulose hydrogel for the effective removal of Cu2+ and Co2+ from wastewater using artificial neural networks

Abstract In this work, n-GCHM was used for the removal of Cu2+ and Co2+ from wastewater. The adsorbent material (n-GCHM) was characterised using SEM and TGA. The following optimum conditions were obtained: a contact time of 120 min and pH 5 for the removal of Cu2+ and Co2+. The maximum adsorption capacity of Cu2+ and Co2+ was 5.8343 mg/g using n-GCHM. The highest percentage removal of Cu2+ and Co2+ on n-GCHM at pH 5 was 80 and 80.5%, respectively. The experimental data successfully fitted to pseudo-second-order kinetic, and also fitted well to the Freundlich isotherm model. The process of adsorption was spontaneous and exothermic in nature. To obtain extensive information on the adsorption process of metal ions on the functional groups of adsorbents, the quantum adsorption mechanism was investigated using DFT. The molecular orbital approach has shown that the HOMO and LUMO were located on –NCN– and LUMO on –NCO–. The quantum adsorption mechanism has shown that the binding energies of Cu2+ and Co2+ on imine functional groups were −60,604.399 and −53649.06 eV, respectively. On the –NCO– functional group, the binding energy was −58587.608 and −51632.618 eV, respectively, for Cu2+ and Co2+. Quantum mechanical methods using the ANN approach have been demonstrated to be accurate.

Enhancing Cd(II) and U(VI) remediation through synergistic utilization of GCN-supported MgFe-layered double hydroxide

Due to the significant concentration of heavy metals in the contaminated area, it presents an imminent threat to both living organisms and the environment. In this research, we concentrate on finding an effective solution for eliminating Cd(II) and U(VI) from water. Our approach involves utilizing MgFe-layered double hydroxide (LDH) nanosheets combined with graphitic carbon nitride (GCN) nanosheets to ensure the effective elimination of these hazardous metal ions. The characterization techniques, including SEM, XPS, XRD, and BET analysis, confirmed the hierarchical layered structure of GCN/MgFe LDH with a significant surface area of 127.91 m2/g. Batch investigations demonstrated that the pH of the solution influences the elimination of both metal ions, while kinetics and equilibrium data well align with a pseudo-second-order model and the Langmuir model (R2 = 0.996–1.0), respectively. GCN/MgFe LDH demonstrated impressive removal capacities of 312.30 mg/g and 273.42 mg/g for Cd(II) and U(VI) respectively. A thermodynamic analysis indicated that the adsorption process of both metal ions was endothermic and spontaneous. Furthermore, the GCN/MgFe LDH can be reused for over five cycles. In the fourth cycle, it maintained a removal percentage of over 95 % for both metal ions when 0.1 M HNO3 was used for desorption. In continuous column tests, the GCN/MgFe LDH reduced metal ion concentrations to levels below USEPA standards (<0.005 mg/L and 0.003 mg/L for Cd(II) and U(VI), respectively) for up to 4000 bed volumes, demonstrating its potential for wastewater treatment.

Activated Charcoal from Coffee Dregs Waste as an Alternative Biosorbent of Cu(II) and Ag(I)

This study examines the use of coffee dregs waste as biosorbents of Cu(II) and Ag(I). Coffee dregs waste still contains a high level of carbon and cellulose for biosorbents production. The production process was started with charcoal activation using H3PO4. The batch method was applied by variations of contact time, the mass of the biosorbent, and the initial concentration of metal ions. The results showed that Cu(II) and Ag(I) were optimally adsorbed at pH 6 and 4, respectively. The amount of adsorbed metal ions increased with adsorption contact time. The adsorption process of both metal ions reaches stability within 60 min and the optimum biosorbent mass is 1 g. Isothermal adsorption studies show that Cu(II) adsorption tends to follow Langmuir isotherm with an adsorption energy of 31.42 kJ/mol and Ag(I) adsorption follows Freundlich isotherms with an adsorption energy of 27.74 kJ/mol. Based on the results, the interaction between metal ions and adsorbents is a chemical adsorption process and coffee dregs charcoal has the potential to adsorb Cu(II) and Ag(I) metal ions.

Adsorption of Cu (II) from Cu Standard Solution Using Expanded Perlite

The research aimed to determine the ability of expanded perlite to adsorb or remove Cu (II) metal ions in the solution. Furthermore can be used to reduce Cu levels in the aquatic environment caused by industrial and mining waste. Expanded perlite is a product of perlite resulting from heating at temperatures above 1000°C. Perlite is a volcanic product contains high silica content and a lot of water content so when heating occurs will increase the porosity and surface area that can cause adsorption. Expanded perlite sized < 1 mm can be utilized in the remediation process of mining waste because it is effective in the adsorption of ions such as Cu so as not to be in aquatic environtment. Expanded perlites, effectively used in the adsorption process, have a grain size of < 1 mm with a dose of 60 g/l. An experimental batch test method was carried out with the parameters of pH, adsorbent dose, and contact time to determine the ability of expanded perlite to adsorb Cu (II). The optimum pH in the Cu (II) metal ion adsorption process was 7 and reached equilibrium within 240 minutes. The adsorption equilibrium (chemical adsorption due to cation exchange) that can be absorbed by 1 gram of expanded perlite is 6.11 mg Cu (II), while the maximum adsorption capacity (physical adsorption due to the hydroxyl group bonded to silica has a high electronegativity value so that it can attract positively charged ions) that can be absorbed by 1 gram of expanded perlite is 1.47 mg Cu (II).

Production of Biochar from Coconut Husks for Adsorption of Heavy Metals in Water

This study focused on the production, characterization, and application of biochar from coconuthusks as an effective and cheap adsorbent for the removal of heavy metals (i.e. Pb, Fe, Mn,and Cr) in water. The biochar was produced by pyrolysis of coconut husk at 600 °C in oxygen-free conditions and then characterized by various surface analysis technologies to explore itsphysical and chemical properties. In the metal adsorption test, the produced biochar gave highmetal removal performance with maximum adsorption capacities of 95.24 mgPb2+/g, 40.16mgFe2+/g, 35.46 mgCr6+/g, and 23.09 mgMn2+/g under pH 5, 4.5, 2, and 5.5, respectively. Studiesin kinetics, isotherms, thermodynamics, and mechanism were then conducted to understandthe adsorption process of metal ions in water using coconut husk biochar.

Preparation of Functionalized Palm Kernel Shell Bio-adsorbent for the treatment of heavy metal-contaminated water

Human beings and living creatures are at great risk because of heavy metal contamination in water resulting from industrialization. On the other hand, millions of tons of palm kernel shells (PKS) and other oil palm wastes are produced every year from oil palm downstream industries. In this study, we attempt to consolidate both problems, where the PKS was oxidized with sulfuric acid for the formation of PKS-Sulfo, where the oxygenated and sulfonated functional groups are attached to the activated carbon. The resulting PKS-Sulfo bio-adsorbent was characterized in detail and was used for the treatment of heavy metal-contaminated water. Different adsorption parameters; pH, concentrations of metal ions, contact time, and adsorbent dosage were optimized. It was found that the PKS-Sulfo bio-adsorbent is highly efficient in adsorbing heavy metal ions; Cr6+, Pb2+, Cd2+, and Zn2+ from their aqueous water solutions. The adsorption process was found to follow the pseudo-second-order model and the Langmuir isotherm was better fitted compared to the Freundlich adsorption isotherm for the adsorption process of the heavy metal ions. Furthermore, the adsorption capacities were also determined for all the metal ions were found to be 99% for Cr6+ and Pb2+ and Cd2+ and Zn2+ was found to be 80 % and 70% respectively. This study opens up a new horizon for the preparation of functionalized bio-adsorbents with the potential for numerous applications, especially for water remediation.

Exploration and removal of multiple metal ions using mixed-linker-architected Zn-MOF in aqueous media

A Zn-based 3D MOF, [Zn2(H3L1)(L2)].H2O named PUC-5 was synthesized using trimesic acid (H3L1) and 1-(3-aminopropyl)Imidazole (L2) by solvothermal method. PUC-5 has been characterized using SCXRD, PXRD, FT-IR, SEM, XPS, TGA, BET and Zeta potential techniques. The PUC-5 exhibited extremely high water and pH stability. We explored the utility of PUC-5 as a sensitive probe for the detection and removal of multiple heavy metal ions (Fe2+, Pb2+ and V5+) from water. The detection limits calculated in the case of Fe2+, Pb2+ and V5+ were 0.129 µM, 0.113 µM and 0.246 µM which were found to be lower than the limits established by the world health organisation (WHO) for drinking water. The detection ability of PUC-5 towards targeted metal ions was further confirmed by Zeta potential, FTIR and XPS techniques. Moreover, the adsorption potential of PUC-5 towards Fe2+, Pb2+ and V5+ was studied by the ICP-MS method. Different kinetic and isotherm models were used to assess the effects of time, temperature, adsorbent content and initial metal ions concentration on PUC-5′s ability to adsorbFe2+, Pb2+, and V5+. The adsorption process of metal ions could be well depicted by Pseudo-second-order kinetics and Langmuir isotherm models suggesting monolayer chemisorption with maximum adsorption capacities of 208.7, 192.6 and 203.6 mg g−1 for Fe2+, Pb2+ and V5+ respectively. Furthermore, the thermodynamic parameters support the spontaneous behaviour and exothermic nature of the adsorption process. Interestingly, PUC-5 is a recyclable material and can be reused with high adsorption efficiency suggesting a high potential of adsorbent towards Fe2+, Pb2+ and V5+.

Preparation of modified reed carbon composite hydrogels for trapping Cu2+, Ni2+ and methylene blue in aqueous solutions.

The pollution of heavy metal ions and organic dyes seriously endangers human health and causes acute environmental problems. The adsorption method is extensively adopted in the treatment of water pollution which is more harmful to human health. In this work, the original reed carbon (ORC) was functionalized by polyethyleneimine (PEI). By means of radical polymerization, PEI-modified reed carbon (PRC), sodium alginate and lysine were made into carbon-composite acrylic hydrogel (SA/LS/PRC). Meanwhile, SEM, FTIR, TGA, and Zeta potential were used to characterize the adsorbent. The elimination capacity of SA/LS/PRC for Cu2+, Ni2+, and Methylene blue (MB) was researched through batch adsorption experiments. The adsorption behavior of SA/LS/PRC is more suitable for the pseudo-second-order kinetic model of chemical removal of pollutants and the Langmuir model relying on monolayer adsorption. The maximum adsorption capacities of SA/LS/PRC for Cu2+, Ni2+ and MB are 1245.27, 1239.47 and 627.29mgg-1, respectively, and the adsorption performance is better than those reported in most literatures. The interaction of Cu2+, Ni2+, and MB were studied via binary mixed adsorption experience. Surface complexation and electrostatic interactions are the major removal mechanisms for contaminants. The adsorption capacity of SA/LS/PRC kept above 81% after five cycles. The SA/LS/PRC green hydrogel can be effectively applied in the mixed adsorption process of heavy metal ions and the removal of dyes.

A review of the application of fungi as an effective and attractive bio-adsorbent for biosorption of heavy metals from wastewater.

One of the most hazardous environmental pollutants is the pollution risen by heavy metal ions in effluents, which is increasing due to the increasing human activity and the development of urbanization. Notwithstanding the economic challenges to control the pollution of effluent treatment processes, it seems necessary to provide effective approaches. The sorption method is widely used due to low-cost, flexibility in design and operation, repeatability, and significant performance. Hence, the need for more environmentally friendly sorbents to eliminate metal ions is greater than ever. Due to the unique features such as the presence of chitin and chitosan in the cell wall, high absorption capacity, environmental friendliness, availability, and cheapness, the use of fungi as adsorbent has received much attention. Therefore, this work tries to address the use of fungi as biosorbents to remove these metals, the dangers of heavy metals, and their sources. Moreover, equilibrium, kinetic, and thermodynamic behaviors of the heavy metal ion adsorption process in the literature are briefly studied.

Characterizing and modeling of oak fruit shells biochar as an adsorbent for the removal of Cu, Cd, and Zn in single and in competitive systems

In this study, the oak fruit shells (OFS) were used to prepare a biochar (OFSBC) obtained by one-step pyrolysis process at 700 °C. The obtained adsorbent was characterized to evaluate physicochemical properties and tested for the adsorption of Cu2+, Cd2+, and Zn2+ in an aqueous solution. The results proved that the prepared adsorbent has a large specific surface area (SBET = 520 m2/g), a large number surface functional groups and a developed porosity. The adsorption equilibrium metal ions onto OFSBC was reached after 4 h of contact time with a removal efficiency 95.29 %, 94.63 %, 82.99 % for Cu2+, Zn2+, and Cd2+, respectively. The Avrami fractional order was the suitable model that describes the kinetic adsorption process of metal ions onto OFSBC. The Freundlich isotherm model fits the experimental data slightly better than other models in single systems. The maximum adsorption capacities of Langmuir that were obtained were in the following order 41.97 mg/g, 41.79 mg/g, and 27.00 mg/g for Cu2+, Cd2+, and Zn2+ ions, respectively. In binary systems the equilibrium adsorption of these ions onto OFSBC was found to be antagonistic in nature and is well described by the extended Freundlich model. The thermodynamic study revealed that the adsorption of these metals was spontaneous and endothermic in nature.The regeneration of the adsorbent was tested in 5 adsorption/desorption cycles, with a slight decrease from cycle 1 to cycle 5. The prepared adsorbent could serve as promising material to remove Cu2+, Cd2+ and Zn2+ effectively from wastewater.

Adsorption of Pb(II) ions from aqueous solutions by magnetite (Fe3O4) nanoparticles functionalized with two different Schiff base ligands

In this study, Fe3O4 magnetic nanoparticles were synthesized using a co-precipitation method and thereby modified with 3-aminopropyltriethoxy-silane (APTES) as the amine precursor, and 4- bromobenzaldehyde (BA) and 2-Formyl-1H-pyrrole (FP) as aldehyde precursors, to create Schiff ligands on the surface. In addition, FT-IR, FE-SEM, TGA-DTG, TEM, and XRD analyses were employed to characterize the nanoparticles. The resultant modified nanoparticles (Fe3O4-BA and Fe3O4-FP) were then applied for Pb(II) removal from aqueous solutions. The kinetic behavior of Pb(II) removal was studied through pseudo-first-order and pseudo-second-order adsorption experiments, resulting in the rate constants. According to the findings, the metal adsorption process followed a pseudo-second-order kinetic reaction. Assessing the equilibrium behavior of the adsorption process through Langmuir and Freundlich models revealed that the adsorption equilibrium data for Pb(II) ions on Fe3O4-BA and Fe3O4-FP followed the Langmuir and Freundlich isotherm models, respectively. Moreover, the results showed that the adsorption process of metal ions by the Fe3O4-BA and Fe3O-FP nanoparticles was affected by operating parameters such as pH, temperature, metal ion concentration and mass of adsorbent.

Adsorption of Chromium Ions from Aqueous Solutions by Synthesized Nanoparticles

In the present manuscript, an attempt has been made to remove chromium metal ions from synthetic effluent using adsorption process. The synthesized titanium dioxide nanoparticles were used as adsorbents. Adsorption studies were performed in batch process. Various characterization of synthesized nanoparticles such as XRD analysis, optical properties of nanoparticles using UV-visible absorption spectroscopy, concentration of chemical bonds, and atomic arrangement using (FTIR) have been performed and analyzed. The dependency of adsorption percentage of metal ions and equilibrium amount of metal adsorbed with respect to pH, adsorbent dosage, initial concentration, and temperature are studied. Mechanisms of metal ion adsorption process explained by various adsorption isotherms and adsorption kinetic models. The criteria for statistical significance of correlation coefficient ( R 2 ) for fitting the experimental data to the various isotherms were tested and analyzed. The experimental results reveal that synthesized titanium dioxide nanoparticles could be used as adsorbents in order to remove chromium ions present in industrial wastewater.

Graphene Oxide@Heavy Metal Ions (GO@M) Complex Simulated Waste as an Efficient Adsorbent for Removal of Cationic Methylene Blue Dye from Contaminated Water.

Graphene oxide (GO) was heavily used in the adsorption process of various heavy metal ions (such as copper (Cu) and iron (Fe) ions), resulting in a huge waste quantity of graphene oxide@metal ions complex. In this research, the authors try to solve this issue. Herein, the GO surface was loaded with divalent (Cu2+) and trivalent (Fe3+) heavy metal ions as a simulated waste of the heavy metal in various removal processes to form GO@Cu and (GO@Fe) composites, respectively. After that, the previous nanocomposites were used to remove cationic methylene blue (MB) dye. The prepared composites were characterized with a scanning electron microscope (SEM), transition electron microscope (TEM), Fourier transmission infrared (FTIR), Raman, and energy-dispersive X-ray (EDS) before and after the adsorption process. Various adsorption factors of the two composites towards MB-dye were investigated. Based on the adsorption isotherm information, the adsorption process of MB-dye is highly fitted with the Langmuir model with maximum capacities (mg g−1) (384.62, GO@Cu) and (217.39, GO@Fe). According to the thermodynamic analysis, the adsorption reaction of MB-species over the GO@Cu is exothermic and, in the case of GO@Fe, is endothermic. Moreover, the two composites presented excellent selectivity of adsorption of the MB-dye from the MB/MO mixture

Nanocatalyst in remediating environmental pollutants

The gradual increase of population and residues excreted from advance industries disturbs our ecological balance. The report of change in climate and environmental pollution is most hot topic around the world. Environmental pollution has become a threat to our life as it may be the root causes of different unwanted diseases. Hence, the degradation of this pollutants are required immediately. However, there are some pollutants which are very hard to degrade and needs more time for remediation. In this process, the novel work of nanotechnology can be applied and the pollutants can be transformed into a harmless one or can be properly remediate. It is possible because of their large surface area, active sites and sufficient functional groups. Besides these, it could transform strong surface complexes with various kinds of pollutants and thereby could efficiently eliminate the pollutants from the aqueous solutions. As a result, nanocatalyst and nanomaterials are generally used for the remediation process. Different kind of nanomaterials including inorganic, carbon materials and polymeric based materials are used in remediation of environment contaminants. Utilizing these novel materials can successfully purified pollutants like heavy metals, dyes, chlorinated organic compounds, organophosphorus compounds, volatile organic compounds, and halogenated herbicides. Furthermore, process like adsorption and photocatalytic reduction of organic pollutants and the adsorption or reduction process of heavy metal ions are usually considered as the one of the major methods to reduce the concentration of pollutants in the surroundings. In context to this, the present review writes up more on enhancement work of nanocatalyst in remediation of environment pollutants and there need for future to bring a clean safety environment.

Effective removal of heavy metal ions by attapulgite supported sulfidized nanoscale zerovalent iron from aqueous solution

Sulfidation of nanoscale zero valent iron (nZVI) has attracted increasing interest for improving the reactivity and selectivity of nZVI towards heavy metal ions. In this study, attapulgite-loaded sulfide modified nZVI (APT/S-nZVI) was synthesized, and used for removal Cr(Ⅵ), Cu(Ⅱ) and Zn(Ⅱ) alone or coexisting. The morphology and structure characterizations indicated that sulfide-modified nZVI particles were well distributed and immobilized on the attapulgite surface. Batch experiments of Cr(Ⅵ), Cu(Ⅱ) and Zn(Ⅱ) removal were conducted at varying mass ratios, S/Fe ratios, pH and initial concentrations. Moreover, kinetic and thermodynamic analyses were used to study the removal process, and possible mechanisms of removal for Cr(Ⅵ), Cu(Ⅱ) and Zn(Ⅱ) were discussed. The results of removal performance tests demonstrated that APT/S-nZVI displayed high removal capacity and fast removal rate for three heavy metal ions compared to the nZVI, which derived from the synergistic effects of the strongly reducing characteristics of nZVI combined with high electronic conductivity of FeS and high surface area of APT. Dynamic studies revealed that the removal process was highly consistent with the pseudo-second-order model for three metal ions adsorption and reaction process. Additionally, combined the value of activation energy, it has been proved that the removal Cr(VI) and Cu(Ⅱ) were controlled by chemical surface-limiting step, and removal Zn(Ⅱ) was controlled by chemically diffusion step. The modification of S changes the removal mechanism between APT/S-nZVI and metal ions, which is closely related to the redox potential of metal ion and the solubility product constant (Ksp) of metal sulfides. Overall, the work suggests that APT/S-nZVI has a good potential for the elimination of micropollutants in the aquatic environment.

Molecular dynamic simulation and artificial intelligence of lead ions removal from aqueous solution using magnetic-ash-graphene oxide nanocomposite

In this work, the heavy metal ions (lead, Pb) adsorption process were studied using an artificial intelligence simulation based model for prediction of the adsorption process by using magnetic ash/graphene oxide (GO) nanocomposite. Also, the adsorption mechanism of Pb ions on the adsorbent were investigated using molecular dynamics (MD) calculations in aqueous solution. Reactivity of structures, ionization energy (I), electron affinity (A), chemical hardness (η), chemical softness (σ), and energy gap (ΔEgap) of all compounds were obtained from the HOMO–LUMO energy levels. The outcomes demonstrated that the adsorption of Pb ions on the adsorbent occurred through electrostatic interactions and van der waals bonding and the lead-water-GO configuration had the highest adsorption affinity according the ΔEgap calculations. The artificial neural network (ANN) with two hidden layers was used for developing the model with a mixture of linear and non-linear transfer functions. The equilibrium (Eq.) concentration of the Pb ion as an important factor in predicting the adsorption capacity of adsorbent was considered for the model output and initial Pb ion concentration as well as solution temperature were assumed as the model inputs. The training and validation procedure of ANN indicated great agreement between the experimental and predicted data according to the high coefficient of determination and low root mean square error (R2 > 0.999, RMSE = 0.086). Based on the simulation results increasing the initial concentration of Pb ion significantly affect the Eq. concentration while the solution temperature had a lower effect on Eq. concentration. The results of this study provide valuable model for pollutants removal. MD calculations and artificial intelligence simulation methods could be an appropriate combined technique for predicting the adsorption behavior of nanocomposite in heavy metal ions removal from the aqueous solution with high accuracy.