The starch modified montmorillonite for the removal of Pb(II), Cd(II) and Ni(II) ions from aqueous solutions

In the present study, we attempted to synthesize a novel sorbent from the starch modified montmorillonite for the removal of Pb(II), Cd(II), and Ni(II) ions from aqueous solutions. Structure and properties of the adsorbent were characterized by Fourier-transformed infrared(FT-IR) spectroscopy, X-ray diffraction (XRD), and Field emission scanning electron microscopic (FE-SEM) techniques. Batch experiments were confirmed through the effect of different conditions including pH, contact time, initial metal concentration and adsorbent dose. Specifically, the optimum value of adsorbent dose was achieved as 20 g/l for the removal of almost metal ions. The adsorption data was fitted with the optimum pH value as 5 for all experiments. The contact time at which the uptake of maximum metal adsorption was observed within 45 min for Pb(II), 90 min for Cd(II), and 60 min for Ni(II). In addition, it was revealed in our study that the equilibrium data obeyed the Langmuir model, and the adsorption kinetic followed a pseudo second-order rate model. Obtained results were noticeable for a modified phyllosilicate adsorbent, and with such a simple and low-cost modification for montmorillonite, the potential of this material as an economical and effective adsorbent for the removal of metal ions from aqueous solution was considerably elevated.     

Surface modification of date palm activated carbonaceous materials for heavy metal removal and CO2 adsorption

In this study, high surface area activated carbon (AC) was prepared from a local palm tree (Phoenix Dactylifera) using a variety of metal carbonates activators and finally achieved an excellent S_BET of 2700 m²/g when Cs₂CO₃ was used as an activating agent at a temperature of 600 °C. Surface modification of AC was carried out using various nitrogen transporting agents, resulting in N-doped ACs with nitrogen content varying from 4.0 to 11.4 %, depending on the functionalizing agents and activators used. The bimodal (presence of micro- as well as meso-porosity) ACs with such excellent surface properties were studied for their CO₂ uptake capacity at two different temperatures (0 and 25 °C) by isotherms recorded at pressure 1 bar and showed a remarkable uptake ability of 3.52 mmol/g (at 25 °C) and 5.6 mmol/g (at 0 °C), respectively. Also, batch experiments with variable pH, contact time, adsorbate concentrations, adsorbent dose, and temperatures were evaluated to understand the mechanism of sorption phenomena of Cr(VI) and Pb(II) achieving > 99.9 % removal capacity by the prepared ACs. Depending on the heavy metal ions being investigated, it was revealed that the pH of the solution and the amount of adsorbent had a direct impact on the total adsorption ability. Nitrogen atoms doped into the carbon frameworks were found to enhance the adsorption in the case of Pb(II) while the removal of Cr(VI) appeared to be unaffected. Maximum adsorption for Cr(VI) was observed at pH 2 and was determined to follow Freundlich isotherm while that of Pb(II) was observed at pH 7 and follows Langmuir isotherm. Best adsorption was found at an adsorbate concentration of 10 ppm and an adsorbent dose of 10 g/L. Kinetic modeling parameters showed the applicability of pseudo-second-order model perfectly.     

Equilibrium,kinetic, and thermodynamic studies of lead ion adsorption from mine wastewater onto MoS2-clinoptilolite composite

This work explored the potential of clinoptilolite, molybdenum sulphide (MoS₂), and MoS₂-clinoptilolite composite in lead (Pb) removal from aqueous medium and industrial mining wastewater. MoS₂-clinoptilolite composite was successfully prepared by a hydrothermal method. The surface properties, structure, and composition of the synthesized composite and the parent compounds were analyzed by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The removal efficiency of lead from aqueous solution was studied in batch-mode experiments. The MoS₂-clinoptilolite was used for the removal of Pb ions (50 mg/L) from an aqueous solution: ~100% of the Pb was removed with a MoS₂-clinoptilolite dose of 0.075 g, pH 6 at 328K within 90 min. The adsorption capacities of Pb onto MoS₂-clinoptilolite were found to be higher than those onto clinoptilolite. Metal ion adsorption behavior was well explained by the Freundlich model, that is, multilayer adsorption of Pb molecules occurred on the heterogeneous surface of adsorbents in case of clinoptilolite, while in the case of MoS₂-clinoptilolite, the Langmuir model was suitable, that is, the adsorption occurred on a monolayer surface. The rate of Pb adsorption was explained by pseudo-second-order model suggesting that the adsorption process is presumably chemisorption. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were calculated, which indicated that the adsorption was spontaneous and exothermic in nature. The selectivity of each adsorbent for Pb was also tested by adding the adsorbents to real gold mine water which contains competitive metal ions.     

磁性纳米粒子富集-电感耦合等离子体发射光谱法测定食具中铬、镍、镉、铅、砷的迁移量

采用氩电弧等离子体法制备磁性碳包铁纳米粒子,考察了其对水溶液中Cr,Ni,Cd,Pb和As的富集能力,建立电感耦合等离子体原子发射光谱同时测定食具中Cr,Ni,Cd,Pb和As迁移量的分析方法。研究了纳米粒子表面经H2O2处理后,pH值、吸附时间、吸附剂用量等因素对各元素富集效率的影响。结果表明,H2O2表面处理可有效提高纳米粒子对待检元素的吸附率。在pH 8.0～9.5范围内,选用30 mg碳包铁纳米粒子定量富集,振荡3 min后,Cr,Ni,Cd,Pb和As均可被磁性碳包铁纳米粒子定量富集,酸性溶液(pH 1～2)可洗脱吸附离子。采用本方法测定了实际样品,各元素回收率在87%～106%之间。     

Enhancement of Cd2+ removal on CuMgAl-layered double hydroxide/montmorillonite nanocomposite: Kinetic,isotherm, and thermodynamic studies

In recent decades, great progress has been made in the application of adsorption processes to mitigate water pollution by hazardous metals. However, developing a highly efficient adsorbent is essential if the adsorption process is to be successfully applied in practical applications. In this study, a CuMgAl-layered double hydroxides/montmorillonite nanocomposite (CuMgAl-LDH/MMt) was prepared, characterized, and then used as a novel adsorbent for adsorption of Cd²⁺ ions from wastewater. The effects of initial pH, adsorbent dosage, agitation speed, particle size, contact time, initial Cd²⁺ concentration, and temperature on the pollutant removal efficiency were analyzed. An isotherm model reading revealed that the results of the experimental work were a good fit with the Freundlich model. The maximum adsorption capacity was reached at 174.87 mg/g under optimal conditions (pH 5, dosage of 0.02 g/l, agitation speed of 150 rpm, and particle size of 87 μm) at 50 ppm after 120 min of adsorption time. Kinetic studies showed that pseudo-second-order models were best fitted to the adsorption data, indicating heterogeneous adsorption of Cd²⁺ ions onto multilayer CuMgAl-LDH/MMt sites, and that the adsorption process is primarily chemical adsorption. Thermodynamic parameters (ΔS^o, ΔH^o, and ΔG^o) demonstrated that Cd²⁺ adsorption onto adsorbent was exothermic and spontaneous. Moreover, the synthesized adsorbent can be recovered after five consecutive cycles with a minimal reduction in the adsorption ability of 29.56 %. The study showed that specific heavy metals can be removed from aqueous solution by a newly prepared adsorbent due to its excellent morphology, high stability under a wide range of conditions, recyclability, and high adsorption capacity.     

Analysis of the role of various biochar in the remediation of heavy metals in contaminated water and its kinetics study

Biochar prepared from agricultural wastes has gained great attention as a cost-effective treatment for metal-contaminated water. In this study, the effectiveness of corn cob and sugarcane bagasse-derived biochar for metals (Pb, Ni, and Cu) removal from an aqueous medium was examined following their physical, chemical, and structural characterization. Batch sorption experiments were carried out by employing the Langmuir and Freundlich equations. The results indicated that separation factor (R_L) values lay in the range of 0 and 1 representing the productive adsorption. The optimum dosage for metal adsorption can be recommended as 30 g L^?1. The optimum adsorption conditions were found at 6.5 and 5.5 pH, 1.5 g adsorbent dose, and at 180 min equilibrium time, for both corn cob and sugarcane bagasse biochars. At pH 6.5, adsorption capacities of Pb, Ni, and Cu were found maximum i.e., 11.34, 15.71, and 11.96 mg kg^?1 for corn cob and 8.96, 15.46, and 12 mg kg^?1, for sugarcane bagasse biochars, respectively. The metal adsorption kinetics was analyzed via four different types of the pseudo-second-order kinetic model. Moreover, the corn cob biochar showed a more pronounced activity in the removal of metals compared to sugarcane bagasse biochar. Hence, it was concluded that corncob and sugarcane bagasse-derived biochars could be utilized as economical bio-adsorbents for the heavy metals removal from wastewater.     

Adsorption of Cr(VI) using activated neem leaves: kinetic studies

In the present study, adsorbent is prepared from neem leaves and used for Cr(VI) removal from aqueous solutions. Neem leaves are activated by giving heat treatment and with the use of concentrated hydrochloric acid (36.5 wt%). The activated neem leaves are further treated with 100 mmol of copper solution. Batch adsorption studies demonstrate that the adsorbent prepared from neem leaves has a significant capacity for adsorption of Cr(VI) from aqueous solution. The parameters investigated in this study include pH, contact time, initial Cr(VI) concentration and adsorbent dosage. The adsorption of Cr(VI) is found to be maximum (99%) at low values of pH in the range of 1-3. A small amount of the neem leaves adsorbent (10 g/l) could remove as much as 99% of Cr(VI) from a solution of initial concentration 50 mg/l. The adsorption process of Cr(VI) is tested with Langmuir isotherm model. Application of the Langmuir isotherm to the system yielded maximum adsorption capacity of 62.97 mg/g. The dimensionless equilibrium parameter, R _L, signifies a favorable adsorption of Cr(VI) on neem leaves adsorbent and is found to be between 0.0155 and 0.888 (0<R _L<1). The adsorption process follows second order kinetics and the corresponding rate constant is found to be 0.00137 g/(mg) (min).     

Micro-column preconcentration/separation using thiacalix[4]arene tetracarboxylate derivative modified mesoporous TiO2 as packing materials on-line coupled to inductively coupled plasma optical emission spectrometry for the determination of trace heavy metals in environmental water samples

A novel adsorbent of thiacalix[4]arene tetracarboxylate derivative modified mesoporous TiO₂ was prepared and was used as a packing material for flow injection (FI) micro-column (20 mm × 4.0 mm i.d.) separation/preconcentration on-line coupled to inductively coupled plasma optical emission spectrometry (ICP-OES) simultaneous determination of trace metals (V, Cu, Pb, Cr) in environmental water samples. The experimental conditions for modified mesoporous TiO₂ packed micro-column separation/preconcentration of the target metals were optimized and the interference of commonly coexisting ions was examined. The adsorption capacities of thiacalix[4]arene tetracarboxylate derivative modified mesoporous TiO₂ for V, Cu, Pb and Cr were found to be 14.0, 11.7, 17.7 and 14.5 mg g^− 1, respectively. The detection limits of the method were 0.09, 0.23, 0.50 and 0.15 µg L^− 1 for V, Cu, Pb and Cr, respectively, with a preconcentration factor of 20. The precision of this method were 1.7% (V), 3.9% (Cu), 4.6% (Pb) and 2.9% (Cr) (n = 7, C = 5 µg L^− 1), respectively. The developed method was applied to the determination of trace heavy metals in real samples and the recoveries for spiked samples were found to be in the range of 88.7-107.1%. For validation, a certified reference material of GSBZ50009-88 environmental water sample was analyzed and the determined values were in good agreement with the certified values.     

Removal of Cd(II) and Pb(II) from aqueous solution by modified attapulgite clay

Three low-cost adsorbents (purified raw attapulgite (A-ATP), high-temperature-calcined attapulgite (T-ATP), and hydrothermal loading of MgO (MgO-ATP)) were prepared as adsorbents for the removal of Cd(II) and Pb(II). By evaluating the effect of the initial solution pH, contact time, initial solution concentration, temperature and coexistence of metal ions on Cd(II) and Pb(II) adsorption, the experimental results showed that MgO-ATP was successfully prepared by hydrothermal reaction and calcination as well as appearing to be a promising excellent adsorbent. At an initial pH of 5.0, A-ATP, T-ATP and MgO-ATP reached maximum adsorption amounts of 43.5, 53.9 and 127.6 mg/g for Pb(II) and 10.9, 11.2, and 25.3 mg/g for Cd(II) at 298 K, respectively. The Cd(II) adsorption on A-ATP was fitted by the Freundlich model, while the adsorption of Pb(II) and Cd(II) on T-ATP and MgO-ATP as well as Pb(II) adsorption on A-ATP agreed with the Langmuir model. All kinetic experimental data favored pseudo second-order model. The calculated thermodynamic parameters suggested that Pb(II) adsorption onto MgO-ATP was spontaneous and exothermic. When considering foreign metal ions, the three adsorbents all presented preferential adsorption for Pb (II). Chemical adsorption had a high contribution to the removal of Cd(II) and Pb(II) by modified attapulgite. In summary, the adsorption was greatly enhanced by the hydrothermal loading of MgO. It aimed to provide insights into the MgO-ATP, which could be able to efficiently remove Cd(II) and Pb(II) and serve as an economic and promising adsorbent for heavy metal-contaminated environmental remediation.     

Optimization of cadmium adsorption from aqueous solutions by functionalized graphene and the reversible magnetic recovery of the adsorbent using response surface methodology

Novel functionalized graphene adsorbent was prepared and characterized using different techniques. The prepared adsorbent was applied for the removal of cadmium ions from aqueous solution. A response surface methodology was used to evaluate the simple and combined effects of the various parameters, including adsorbent dosage, pH, and initial concentration. Under the optimal conditions, the cadmium removal performance of 70% was achieved. A good agreement between experimental and predicted data in this study was observed. The experimental results revealed of cadmium adsorption with high linearity follow Langmuir isotherm model with maximum adsorption capacity of 502 mg g^?1, and the adsorption data fitted well into pseudo‐second order model. Thermodynamic studies showed that adsorption process has exothermic and spontaneous nature. The recommended optimum conditions are: cadmium concentration of 970 mg L^?1, adsorbent dosage of 1 g L^?1, pH of 6.18, and T = 25 °C. The magnetic recovery of the adsorbent was performed using a magnetic surfactant to form a noncovalent magnetic functionalized graphene. After magnetic recovery of the adsorbent both components (adsorbent and magnetic surfactant) were recycled by tuning the surface charges through changing the pH of the solution. Desorption behavior studied using HNO₃ solution indicated that the adsorbent had the potential for reusability.     

Biosorption of lead from aqueous solution by seed powder of Strychnos potatorum L.

In the present study, Pb(II) removal efficiency of Strychnos potatorum seed powder (SPSP) from aqueous solution has been investigated. Batch mode adsorption experiments have been conducted by varying pH, contact time, adsorbent dose and Pb(II) concentration. Pb(II) removal was pH dependent and found to be maximum at pH 5.0. The maximum removal of Pb(II) was achieved within 360 min. The Lagergren first-order model was less applicable than pseudo-second-order reaction model. The equilibrium adsorption data was fitted to Langmuir and Freundlich adsorption isotherm models to evaluate the model parameters. Both models represented the experimental data satisfactorily. The monolayer adsorption capacities of SPSP as obtained from Langmuir isotherm was found to be 16.420 mg/g. The FTIR study revealed the presence of various functional groups which are responsible for the adsorption process.     

Adsorption of Chromium (VI) on <Emphasis Type="Italic">Azadirachta Indica</Emphasis> (Neem) Leaf Powder

A novel adsorbent was developed from mature leaves of the Neem tree (Azadirachta Indica) for removing metal ions from water. The adsorbent, in the form of fine powder, was found to be very effective in removing chromium (VI) from aqueous solution. The adsorption was carried out in a batch process taking different concentrations of the metal ion in aqueous solution with variation in adsorbent amount, pH, agitation time and temperature. The suitability of the adsorbent was tested with Langmuir and Freundlich isotherms and with various equilibrium kinetic data. A small amount of the Neem Leaf Powder (NLP) (1.6 g dm^–3) could remove as much as 87% of Cr (VI) in 300 min from a solution of concentration 14.1 mg dm^–3 at 300 K. The optimum range of pH for the adsorption process was 4.5–7.5 and since the natural pH of the Cr (VI) solution was 5.5, no addition of acid or alkali was necessary for achieving maximum adsorption. The adsorption coefficients indicated a high potentiality for the NLP to be used as an adsorbent for removing Cr (VI) from water.     

Chemically modified silica gel with p-dimethylaminobenzaldehyde for selective solid-phase extraction and preconcentration of Cr(III), Cu(II), Ni(II), Pb(II) and Zn(II) by ICP-OES

Silica gel-bound amines phase modified with p-dimethylaminobenzaldehyde (p-DMABD) was prepared based on chemical immobilization technique. The product (SG-p-DMABD) was used as an adsorbent for the solid-phase extraction (SPE) Cr(III), Cu(II), Ni(II), Pb(II) and Zn(II) prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The uptake behaviors of SG-p-DMABD for extracting these metal ions were studied using batch and column procedures. For the batch method, the optimum pH range for Cr(III) and Ni(II) extraction was ≥ 3, for Cu(II), Pb(II) and Zn(II) extraction it was ≥ 4. For simultaneous enrichment and determination of all the metals on the newly designed adsorbent, the pH value if 4.0 was selected. All the metal ions can be desorbed with 2.0 mL of 0.5 mol L^− 1 of HCl. The results indicate that SG-p-DMABD has rapid adsorption kinetics using the batch method. The adsorption capacity for these metal ions is in the range of 0.40-1.15 mmol g^− 1, with a high enrichment factor of 125. The presence of commonly coexisting ions does not affect the sorption capacities. The detection limits of the method were found to be 1.10, 0.69, 0.99, 1.10 and 6.50 μg L^− 1 for Cr(III), Cu(II), Ni(II), Pb(II) and Zn(II), respectively. The relative standard deviation (RSD) of the method under optimum conditions was 5.0% (n = 8) for all metal ions. The method was applied to the preconcentration of Cr(III), Cu(II), Ni(II), Pb(II) and Zn(II) from the certified reference material (GBW 08301, river sediment) and water samples with satisfactory results.     

Retention dynamics of multi-metal contaminants from pond ash slurry onto fine grained soil

The coal fly ashes contain high concentration of toxic metals. The sorption plays crucial part to retard the movement of contaminants through the liner. In the present investigation to examine the potential of fine-grained soil as liner material, obtained from bank of River Ganga, was assessed in terms of its adsorption capability. Batch adsorption of Pb(II) and Cr(VI) were performed. Maximum adsorption of Cr(VI) (65.76%) at pH 3 for adsorbate and adsorbent dose of 5 ​mg/L and 2 ​g/L and maximum adsorption of Pb(II) (96.84%) at pH 5 for adsorbate and adsorbent dose of 5 ​mg/L and 1.5 ​g/L, respectively, were observed. Adsorption of Pb(II) and Cr(VI) follow Freundlich isotherm equation. The soil column studies were performed at various bed heights (2, 3 and 5 ​cm) in down flow mode. The tracer studies were conducted using NaCl to estimate the hydrodynamic parameters and they were considered as input parameters for modelling of fate and transport of contaminants in soil using HYDRUS 1D software for assessing the potential use of soil as liner material in ash pond structures.     

Trace element determination in thorium oxide using total reflection X-ray fluorescence spectrometry

Applicability of Total Reflection X-ray Fluorescence (TXRF) spectrometry for the determination of trace metals at concentration of µg/g level in thorium oxide was studied. The TXRF spectrometer was calibrated using a multielement standard solution and the method was validated by analyzing another multielement standard solution. Sample preparation conditions were optimized for the TXRF determinations of trace metals in thorium oxide. The elements K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Ba and Pb present in thorium oxide standards were determined after dissolving them in HNO₃/HF mixture and separating the bulk matrix, thorium, by solvent extraction using tri-n-butyl phosphate (TBP) and tri-n-octyl phosphine oxide (TOPO) as extractants. A comparison of TXRF determined concentrations of trace elements Ca, V, Cr, Mn, Fe, Ni and Cu with the certified values shows that TXRF determined concentrations have an RSD of 20% (1 s for n = 4) and are within an agreement of 20% of the certified values in most of the cases.     

Adsorption of antimony using amino-functionalized magnetic MIL-101(Cr): Optimization by response surface methodology

Amino-functionalized magnetic MIL-101(Cr) was prepared via a one-step solvothermal method, characterized, and applied in adsorptive Sb(III) removal. The effects of solution pH, adsorbent dosage, and coexisting substances on the adsorption of Sb(III) by MIL-101(Cr)–NH₂/MnFe₂O₄ were studied. The adsorption kinetics were analyzed using pseudo-first order, pseudo-second order, intraparticle diffusion, and Elovich models, while Freundlich and Langmuir isotherm models were used to fit the experimental data. The pseudo-second-order kinetic model provided the best fit for the kinetic data. The maximum adsorption capacity of MIL-101(Cr)–NH₂/MnFe₂O₄ for Sb(III) was 91.07 ​mg/g, as calculated using the Langmuir adsorption isotherm model. Thermodynamic analysis revealed that the adsorption of antimony onto MIL-101(Cr)–NH₂/MnFe₂O₄ is spontaneous and endothermic, while response surface optimization revealed that the optimal conditions for Sb(III) adsorption by MIL-101(Cr)–NH₂/MnFe₂O₄ are an adsorbent loading of 222.55 ​mg/L, a pH of 4.5, and a temperature of 294.59 ​K. The predicted adsorption capacity of MIL-101(Cr)–NH₂/MnFe₂O₄ for Sb(III) is only a 1.8% deviation from the actual value. Furthermore, MIL-101(Cr)–NH₂/MnFe₂O₄ exhibits strong magnetism, allowing it to be separated from wastewater using a magnet. Finally, a preliminary economic analysis showed that the cost of treating a ton wastewater containing 25 ​mg/L antimony using this composite would be 26.24 USD. Thus, MIL-101(Cr)–NH₂/MnFe₂O₄ is promising for treatment of Sb(III)-containing wastewater.     

Preparation and characterization of nanocomposite,silica aerogel,activated carbon and its adsorption properties for Cd (II) ions from aqueous solution

A novel composite adsorbent, silica aerogel activated carbon was synthesized by sol-gel process at ambient pressure drying method. The composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Nitrogen adsorption/desorption isotherms (BET).In the present study, the mentioned adsorbent was used moderately for the removal of cadmium ions from aqueous solutions and was compared with two other adsorbents of cadmium, activated carbon and silica aerogel. The experiments of Cd adsorption by adsorbents were performed at different initial ion concentrations, pH of the solution, adsorption temperature, adsorbent dosage and contact time. Moreover, the optimum pH for the adsorption was found to be 6.0 with the corresponding adsorbent dosage level of 0.1 g at 60 °C temperature. Subsequently, the equilibrium was achieved for Cd with 120 min of contact time.Consequently, the results show that using this composite adsorbent could remove more than 60% of Cd under optimum experimental conditions. Langmuir and Freundlich isotherm model was applied to analyze the data, in which the adsorption equilibrium data were correlated well with the Freundlich isotherm model and the equilibrium adsorption capacity (q_e) was found to be 0.384 mg/g in the 3 mg/L solution of cadmium.     

A novel green synthesis of Fe3O4 magnetic nanorods using Punica Granatum rind extract and its application for removal of Pb(II) from aqueous environment

We described a novel and eco-friendly approach to remove toxic heavy metal of Pb(II) by using dimercaptosuccinic acid (DMSA) anchored Fe₃O₄ magnetic nanorods (MNRs) which were synthesized via facile method utilizing Punica Granatum rind extract which was a non toxic waste material. The DMSA@Fe₃O₄ MNRs were characterized by X-ray diffraction (XRD), Fourier transformed infrared analysis (FT-IR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), nitrogen adsorption and desorption techniques, and vibrating sample magnetometer (VSM). These DMSA@Fe₃O₄ MNRs have been used for the removal of Pb(II) from aqueous solution. The adsorption isotherm data fitted well with Langmuir isotherm and Freundlich model, the monolayer adsorption capacity was found to be 46.18 mg/g at 301 K. The experimental kinetic data fitted very well with the pseudo-second-order model. The results indicate that the biogenic synthesized DMSA@Fe₃O₄ MNRs act as significant adsorbent material for removal of Pb (II) from aqueous environment.     

麦麸对重金属离子的吸附性能研究

以麦麸为天然吸附剂,从水溶液中去除重金属离子.实验表明,麦麸对重金属离子有优良的吸附性能.在约10min内达到吸附平衡,吸附容量分别为:Hg2 70mg/g、Pb2 63mg/g、Cd2 21mg/g、Cu2 15mg/g、Ni2 13mg/g及Cr3 9.3mg/g;吸附速率很快,并且对上述金属离子有良好的选择性.     

Predictive modeling and computational machine learning simulation of adsorption separation using advanced nanocomposite materials

Adsorption process was simulated in this study for removal of Hg and Ni from water using nanocomposite materials. The used nanostructured material for the adsorption study was a combined MOF and layered double hydroxide, which is considered as MOF-LDH in this work. The data were obtained from resources and different machine learning models were trained. We selected three different regression models, including elastic net, decision tree, and Gradient boosting, to make regression on the small data set with two inputs and two outputs. Inputs are Ion type (Hg or Ni) and initial ion concentration in the feed solution (C₀), and outputs are equilibrium concentration (Ce) and equilibrium capacity of the adsorbent (Qe) in this dataset. After tuning their hyper-parameters, final models were implemented and assessed using different metrics. In terms of the R2-score metric, all models have more than 0.97 for Ce and more than 0.88 for Qe. The Gradient Boosting has an R2-score of 0.994 for Qe. Also, considering RMSE and MAE, Gradient Boosting shows acceptable errors and best models. Finally, the optimal values with the GB model are identical to dataset optimal: (Ion = Ni, C₀ = 250, Ce = 206.0). However, for Qe, it is different and is equal to (Ion = Hg, C0 = 121.12, Ce = 606.15). The results revealed that the developed methods of simulation are of high capacity in prediction of adsorption for removal of heavy metals using nanostructure materials.