Insight into kinetics and thermodynamics properties of multicomponent lead(II), cadmium(II) and manganese(II) adsorption onto Dijah-Monkin bentonite clay

Multicomponent adsorption of lead(II), cadmium(II) and manganese(II) by Nigerian Dijah-Monkin bentonite clay was investigated. The clay samples were characterized for elemental composition, cation exchange capacity and textural properties. Natural bentonite exhibits cation exchange capacity of 47.7?meq/100?g and specific surface area of 23.5?m²/g. Manganese(II) displays higher values of rate constant than lead(II) in multimetals adsorption. However, lead(II) is favorably adsorbed onto bentonite adsorbents at different concentrations studied. The multimetals adsorption onto bentonite clay samples is site selective and site specific. The pseudo-second-order kinetics model gave a better fit to the adsorption data, suggesting ion exchange and/or complex formation. The adsorption mechanism could be described by intraparticle diffusion with some restriction of metals diffusion due to film or boundary layer. Also, the multicomponent adsorption is endothermic and becomes more spontaneous as temperature increased from 303 to 338?K. Nigerian bentonite clay in its natural form is a promising adsorbent for multimetals removal in aqueous solution.     

Adsorption of lead(II) ions onto 8-hydroxy quinoline-immobilized bentonite

In this study, the immobilization of 8-hydroxy quinoline onto bentonite was carried out and it was then used to investigate the adsorption behavior of lead(II) ions from aqueous solutions. The changes of the parameters of pH, contact time, initial lead(II) ions concentration and temperature were tested in the adsorption experiments. The XRD, FTIR, elemental and thermal analyses were done to observe the immobilization of 8-hydroxy quinoline onto natural bentonite. The adsorption was well described by the Langmuir adsorption isotherm model at all studied temperatures. The maximum adsorption capacity was 142.94mgg(-1) from the Langmuir isotherm model at 50 degrees C. The thermodynamic parameters implied that the adsorption process is spontaneous and endothermic. The kinetic data indicate that the adsorption fits well with the pseudo-second-order kinetic model. 8-Hydroxy quinoline-immobilized bentonite can be used as well respective adsorbent for the removal of the heavy metal pollutants according to the results.     

Immobilization of 2,2'-dipyridyl onto bentonite and its adsorption behavior of copper(II) ions

In this study, the immobilization of 2,2'-dipyridyl onto bentonite was firstly carried out and it was then used for the adsorption of copper(II) ions from aqueous solutions. The variation of the parameters of pH, contact time, initial copper(II) concentration and temperature were investigated in the adsorption experiments. The XRD, FTIR, elemental and thermal analyses were performed to observe the immobilization of 2,2'-dipyridyl onto natural bentonite. The adsorption data obtained were well described by the Langmuir adsorption isotherm model at all studied temperatures. The results indicated that the maximum adsorption capacity was 54.07 mg g(-1) from the Langmuir isotherm model at 50 degrees C. The thermodynamic parameters indicated that the adsorption process is spontaneous, endothermic and chemical in nature. The kinetic parameters of the adsorption were calculated from the experimental data. According to these parameters, the best-fit was obtained by the pseudo-second-order kinetic model. The results showed that 2,2'-dipyridyl-immobilized bentonite can be used as the effective adsorbent for the removal of heavy metal contaminants.     

Biosorption of cadmium (II) and lead (II) from aqueous solutions using mushrooms: A comparative study

Sorption capacity of oyster mushroom (Pleurotus platypus), button mushroom (Agaricus bisporus) and milky mushroom (Calocybe indica) were evaluated on biosorption of heavy metals, viz. cadmium (II) and lead (II) from aqueous solutions. The optimum sorption conditions were studied for each metal separately. The desired pH of the aqueous solution was found to be 6.0 for the removal of cadmium (II) and 5.0 for removal of lead (II) for all the mushrooms. The percent removal of both the metals was found to increase with the increase in biosorbent dosage and contact time. The fitness of the biosorption data for Langmuir and Freundlich adsorption models was investigated. It was found that biosorption of cadmium (II) and lead (II) ions onto the biomass of the three mushrooms were better suitable to Langmuir than Freundlich adsorption model. P. platypus showed the highest metal uptake potential for cadmium (q_max 34.96 mg/g) whereas A. bisporus exhibited maximum potential for lead (q_max 33.78 mg/g). Milky mushroom showed the lowest metal uptake capacity for both the metals. The present data confirms that mushrooms may be used as efficient biosorbent for the removal of cadmium (II) and lead (II) ions from aqueous solution.     

Synthesis and application of a novel mesoporous SBA-15 sorbent functionalized by 2,4 dinitrophenylhydrazine (DNPH) for simultaneous removal of Pb(II), Cr(III), Cd(II) and Co(II) from aqueous solutions: Experimental design,kinetic, thermodynamic,and isotherm aspects

Heavy metal cations are the most common group of pollutants which significantly contribute to the pollution of aquatic systems. Among the heavy metal cations, lead, chromium, cadmium and cobalt are the most abundant cations present in wastewaters. In this work, a novel sorbent was synthesized via functionalization of chloro-mesoporous SBA-15 with 2,4- dinitrophenylhydrazine. The adsorbent was identified by various characterization techniques and then was used for adsorption of Pb(II), Cr(III), Cd(II), and Co(II). and then the response surface methodology was employed to study the influence, and interaction of different parameters. According to the results, the optimized adsorption capacity of 242.50, 214.72, 187.86, 166.46 mg/g was obtained respectively for the studied cations. furthermore, the sorption of cations was fast and the process achieve to equilibrium within 23.65, 20.31, 24.05 min for Pb(II), Cr(III), Cd(II) and within 19.88 min for Co(II). The adsorbent regenerated by a mixture of nitric acid and methanol could be recycled without losing a remarkable amount of capacity. The results analyzed with various isotherm models were best conformed to the Langmuir model.     

Investigation of Cs(I) and Sr(II) removal using nanoporous bentonite

ABSTRACT

Bentonites are types of clays made up the dominant constituent of montmorillonite. Four types of nano-porous and nano-structured commercial bentonite clays were studied in detail for their physicochemical and mineralogical properties vs. Cs and Sr adsorption. The instrumental analyses to study samples were X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET) surface area measurements, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and thermogravimetry (TG). The XRF and peaks of XRD patterns at 2θ?=?8, 19.9, 35, 55, and 62 clearly indicated that the main component of the bentonite samples was montmorillonite. The BET analysis showed that B1 has the highest specific surface area among the other samples which its single and multiple point BET surface area were equal to 84.85 and 85.94?m²?g^?1, respectively. These values represents the amount of montmorillonite and adsorption capacity of samples. The physicochemical, structural and morphological characteristics of different samples were investigated through instrumental analysis. The results of separation processes of Cs(I) and Sr(II) showed 59.75 and 45.5% adsorption capacities for B3 and B2 which were the highest values among the others. The results lead to the conclusion that samples B3 had a good adsorption capacity to remove Cs(I) and Sr(II).     

Effect of quaternary ammonium cation loading and pH on heavy metal sorption to Ca bentonite and two organobentonites

Sorption of four heavy metals (Pb, Cd, Zn and Hg) to calcium bentonite (Ca bentonite), hexadecyltrimethylammonium bentonite (HDTMA bentonite) and benzyltriethylammonium bentonite (BTEA bentonite) was measured as a function of the quaternary ammonium cation (QAC) loading at 25, 50 and 100% of the clay's cation-exchange capacity (CEC). The effects of pH on the surface charge of the clays and heavy metal sorption were also measured. Sorption of Cd, Pb, and Zn was non-linear and sorption of all three metals by HDTMA and BTEA bentonites decreased as the QAC loading increased from 25 to 100%. In most cases, sorption of these metals to 25% BTEA and 25% HDTMA bentonite was similar to or greater than sorption to Ca bentonite. Hg sorption was linear for both HDTMA and BTEA bentonite. No significant effect on Hg sorption was observed with increasing QAC loading on BTEA bentonite. However, an increase of Hg sorption was detected with increasing QAC loading on HDTMA bentonite. This behavior suggests that a process different than cation exchange was the predominant Hg sorption mechanism. Cd, Pb, and Zn sorption decreased with pH. However, this effect was stronger for Cd and Pb than Zn. Hg sorption varied inversely with pH. QAC loading affected the surface charge of the clays. Twenty-five and 50% loading of BTEA cations increased the negative charge on the clay's surface relative to the untreated clay, without affecting the zero point of charge (ZPC) of the clay. Increased QAC loading on HDTMA bentonite causes the surface charge to become more positive and the ZPC increased. One hundred percent of HDTMA bentonite maintained a positive surface charge over the range of pH values tested. The organoclays studied have considerable capacity for heavy metal sorption. Given that prior studies have demonstrated the strong sorption capacity of organoclays for nonionic organic pollutants, it is likely that organoclays can be useful sorbents for the treatment of effluent streams containing both organic contaminants and heavy metals.     

Bromine pretreated chitosan for adsorption of lead (II) from water

Pollution by heavy metals like lead (II) is responsible for health hazards and environmental degradation. Adsorption is a prevalent method applied for removal of heavy metal pollutants from water. This study explored adsorption performances of 30% bromine pretreated chitosan for lead (II) abatement from water. Bromine pretreatment alters porosity and specific surface area of chitosan by means of physicochemical interaction with cationic sites of chitosan skeleton, besides imparting anionic alteration at amino linkages of chitosan, to remove lead (II) by chemical interactions on superfluous active sites as characterized by FTIR, SEM, DTA and elemental analysis. Lead adsorptions were studied in batch mode by varying parameters viz. pH, bromine loading, sorbent dosage, initial lead concentration, contact time and temperature. The adsorption equilibrium data was well fitted to Freundlich isotherm and maximum sorption capacity of 30% bromine pretreated chitosan sorbent was 1·755 g/kg with 85–90% lead removal efficiency. Though cost and applicability of sorbent is unproven, yet contrast to raw chitosan derivatives, activated carbons and some resins, 30% bromine pretreated chitosan endow benign and efficient lead abatement technique.     

Sorption of Pb(II) on sodium polyacrylate modified bentonite

Bentonite is widely used in various anti-seepage systems in landfills and is often exposed to leachate that are strongly acidic and have high concentrations of heavy metals. However, natural bentonite cannot resist the damage caused by cations and adsorbs harmful substances from the liquid in the process of permeation simultaneously. In order to solve this obstacle problem, we investigate the sorption characteristics of previous sodium polyacrylate bentonite (SPB), which has the low permeability and chemical resistance. A series of batch sorption experiments were performed to evaluate the degree of influence of parameters (contact time, pH, temperature, and concentration of Pb(II)). The resultant SPB samples were characterized using thermogravimetric analysis and scanning electron microscopy. The results indicated that negatively charged hydrophilic group (carboxyl group, -COOH) of sodium polyacrylate formed a directional arrangement and wrapped the layers of bentonite. This makes the polyacrylate sodium membrane to allow water to pass through easily and block the cations, thereby protecting bentonite from the cation exchange reaction. Compared with raw bentonite (RB), the sorption of Pb(II) of SPB was significantly improved in acid, and the maximum sorption capacity increased by about 20%, reaching 72.89 mmol/100 g. Thus, SPB is an ideal impermeable material to block the leachate and it exhibits low permeability, chemical resistance, and high adsorption for heavy metals.     

Comparative adsorption of Cu(II), Zn(II), and Pb(II) ions in aqueous solution on the crosslinked chitosan with epichlorohydrin

The crosslinked chitosans synthesized by the homogeneous reaction of chitosan in aqueous acetic acid solution with epichlorohydrin were used to investigate the adsorptions of three metals of Cu(II), Zn(II), and Pb(II) ions in an aqueous solution. The crosslinked chitosan characterized by 13CNMR, SEM, and elemental analysis, and the effects of pH and anion on the adsorption capacity were carried out. The dynamical study demonstrated that the adsorption process was followed the second-order kinetic equation. The results obtained from the equilibrium isotherms adsorption studies of three metals of Cu(II), Zn(II), and Pb(II) ions by being analyzed in three adsorption models, namely, Langmuir, Freundlich, and Dubinnin-Radushkevich isotherm equations, indicated to be well fitted to the Langmuir isotherm equation under the concentration range studied, by comparing the linear correlation coefficients. The order of the adsorption capacity (Qm) for three metal ions was as follows: Cu2+>Pb2+>Zn2+. This technique for syntheses of the crosslinked chitosans with epichlorohydrin via the homogeneous reaction in aqueous acetic acid solution showed that the adsorptions of three metal ions in aqueous solution were followed the monolayer coverage of the adsorbents through physical adsorption phenomena.     

Effects of soil properties on surfactant adsorption

Abstract

The effects of surface area, soil organic matter (SOM) content, and cation exchange capacity (CEC) of natural soils and clays on the adsorption capacity of cationic, anionic, and nonionic surfactants in water‐solid systems were investigated based on the adsorption isotherm analysis. The sorption capacity for a cationic surfactant was proportional to the CEC of the solids. For both anionic and nonionic surfactants, the sorption capacity was related to the soil mineral fraction. However, other soil properties probably affect the practical sorption. The investigated soil properties were treated case by case.     

Adsorption of Cd(II), Cu(II) and Ni(II) ions by Lemna minor L.: effect of physicochemical environment

The free floating macrophyte Lemna minor L. was harvested locally. Untreated, acid pretreated (H2SO4), alkali pretreated (NaOH) biomass were used for adsorption of copper, cadmium and nickel ions from aqueous solutions. The effect of initial pH, initial metal concentration and multi metal interaction were carried out in a batch system. The equilibrium adsorption was reached within 40-60 min. The Langmuir and Freundlich models were used for describing of adsorption isotherm data. The maximum adsorption capacities of alkali pretreated biomass were determined as 83, 69 and 59 mg g(-1) for the Cd(II), Cu(II) and Ni(II) ions, respectively. The pseudo first- and second-order intraparticle diffusion models were used to describe the adsorption kinetics. The experimental data fitted to pseudo second-order kinetic. Adsorption capacity decreased with acid pretreatment; however alkali pretreatment was not affected significantly adsorption capacity and adsorption capacity a little increased according to native biomass. The FT-IR results of Lemna biomass showed that biomass has different functional groups and these functional groups are able to react with metal ions in aqueous solution.     

The chemically crosslinked metal-complexed chitosans for comparative adsorptions of Cu(II), Zn(II), Ni(II) and Pb(II) ions in aqueous medium

The chemically crosslinked metal-complexed chitosans were synthesized by using the ion-imprinting method from a chitosan with four metals (Cu(II), Zn(II), Ni(II) and Pb(II)) as templates and glutaraldehyde as a crosslinker. The influences of adsorption conditions, including molar ratios of crosslinker/chitosan and pH changes, were studied. They were used to investigate for comparative adsorptions of Cu(II), Zn(II), Ni(II) and Pb(II) ions in an aqueous medium. They were demonstrated the comparative adsorptions of Cu(II), Zn(II), Ni(II) and Pb(II) ions in the orders of the adsorbed amounts with templates: Cu(II) approximately Pb(II)>Zn(II) approximately Ni(II), Zn(II)>Cu(II) approximately Pb(II)>Ni(II), Ni(II)>Pb(II)>Zn(II)>Cu(II) and Pb(II) approximately Cu(II)>Zn(II)>Ni(II), respectively. In addition, the dynamical study showed to be well followed the second-order kinetic equation in the adsorption process. At the same time, the equilibrium adsorption data were fitted in three adsorption isotherm models, namely, Langmuir, Freundlich, and Dubinin-Radushkevich to show very good fits in the Langmuir isotherm equation for the monolayer adsorption process. The most important aspect of the chemically crosslinked metal-complexed chitosans with glutaraldehyde demonstrated to afford a higher adsorption capacity, and a more efficient adsorption toward metals in an aqueous medium.     

Optimization,Kinetics, and Equilibrium Studies on the Removal of Lead(II) from an Aqueous Solution Using Banana Pseudostem as an Adsorbent

Natural adsorbents such as banana pseudostem can play a vital role in the removal of heavy metal elements from wastewater. Major water resources and chemical industries have been encountering difficulties in removing heavy metal elements using available conventional methods. This work demonstrates the potential to treat various effluents utilizing natural materials. A characterization of banana pseudostem powder was performed using environmental scanning electron microscopy (ESEM) and Fourier-transform infrared (FTIR) spectroscopy before and after the adsorption of lead(II). Experiments were carried out using a batch process for the removal of lead(II) from an aqueous solution. The effects of the adsorption kinetics were studied by altering various parameters such as initial pH, adsorbent dosage, initial lead ion concentration, and contact time. The results show that the point of zero charge (PZC) for the banana pseudostem powder was achieved at a pH of 5.5. The experimental data were analyzed using isotherm and kinetic models. The adsorption of lead(II) onto banana pseudostem powder was fitted using the Langmuir adsorption isotherm. The adsorption capacity was found to be 34.21 mg·g^–1, and the pseudo second-order kinetic model showed the best fit. The optimum conditions were found using response surface methodology. The maximum removal was found to be 89%.     

Kinetics and equilibrium isotherms of adsorption of Pb(II) and Cu(II) onto raw and arginine-modified montmorillonite

Arg-Mt, was fabricated by modifying sodium montmorillonite (Na-Mt) with Arginine monohydrochloride (Arg salt), to adsorb Pb(II) and Cu(II) in aqueous solution. The X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectrum, thermal analysis (TG/DTG), Brunauer-Emmett-Teller (BET) and Scanning electron microscope (SEM) were employed to investigate the properties of Na-Mt and Arg-Mt. The effects of the amount of modifier, pH value, the initial concentration of M(II), temperature and contact time were tested in a single adsorption system. The isotherm model was well matched with the Langmuir curve and the kinetic adsorption fitted well with the pseudo-second-order rate equation. The saturated adsorption of Pb(II) and Cu(II) by Arg-Mt were 124.69 and 29.15?mg/g, respectively, which were higher than that of Na-Mt (89.08 and 23.93?mg/g). The thermodynamic equation indicated that the adsorption process was spontaneous, endothermic, and the randomness of the samples changed a little after adsorption. The adsorption capacity of heavy metal ions in the binary co-adsorption system was poor than single adsorption system. Furthermore, the adsorbed M(II) onto Arg-Mt can hardly be dissolved under weak acidic condition (pH?>?4) according to the desorption experiments. High-efficiency and low-cost make Arg-Mt to be used in the removal of heavy ions in aqueous solution.     

Competitive adsorption of Cu (II), Co (II) and Ni (II) from their binary and tertiary aqueous solutions using chitosan-coated perlite beads as biosorbent

A new composite chitosan-coated biosorbent was prepared and was used for the removal and recovery of heavy metals from aqueous solution. In the present investigation, equilibrium adsorption characteristics of Cu (II), Ni (II), and Co (II) from their binary and tertiary solution on newly developed biosorbent chitosan-coated perlite beads were evaluated through batch and column studies. These beads were characterized by using FTIR, EDXRF and surface area analysis techniques. The effect of various biosorption parameters like effect of pH, agitation time, concentration of adsorbate and amount of adsorbent on extent of adsorption was investigated. The adsorption follows Lagergren first order kinetic model. The equilibrium adsorption data were fitted to Freundlich and Langmuir adsorption isotherm models and the model parameters were evaluated. Both the models represent the experimental data satisfactorily. The sorbent loaded with metal was regenerated with 0.1N NaOH solution. Furthermore the column dynamic studies indicate the re-usage of the biosorbent.     

Competitive adsorption of copper(II), cadmium(II), lead(II) and zinc(II) onto basic oxygen furnace slag

Polluted and contaminated water can often contain more than one heavy metal species. It is possible that the behavior of a particular metal species in a solution system will be affected by the presence of other metals. In this study, we have investigated the adsorption of Cd(II), Cu(II), Pb(II), and Zn(II) onto basic oxygen furnace slag (BOF slag) in single- and multi-element solution systems as a function of pH and concentration, in a background solution of 0.01M NaNO(3). In adsorption edge experiments, the pH was varied from 2.0 to 13.0 with total metal concentration 0.84mM in the single element system and 0.21mM each of Cd(II), Cu(II), Pb(II), and Zn(II) in the multi-element system. The value of pH(50) (the pH at which 50% adsorption occurs) was found to follow the sequence Zn>Cu>Pb>Cd in single-element systems, but Pb>Cu>Zn>Cd in the multi-element system. Adsorption isotherms at pH 6.0 in the multi-element systems showed that there is competition among various metals for adsorption sites on BOF slag. The adsorption and potentiometric titrations data for various slag-metal systems were modeled using an extended constant-capacitance surface complexation model that assumed an ion-exchange process below pH 6.5 and the formation of inner-sphere surface complexes at higher pH. Inner-sphere complexation was more dominant for the Cu(II), Pb(II) and Zn(II) systems.     

Chitosan selectivity for removing cadmium (II), copper (II), and lead (II) from aqueous phase: pH and organic matter effect

The aim of this study was to investigate the selectivity of chitosan for cadmium, copper and lead in the presence and absence of natural organic matter (NOM) in different pH solutions. Adsorption isotherms of one and three adsorbates at initial concentration of 5-100mg/L were carried out in batch reactors at pH 4, 5, or 7 and 25 degrees C in reactive and clarified water. The chitosan employed had a MW of 107.8 x 10(3)g/mol and degree of acetylation (DA) of 33.7%. The chitosan adsorption capacity at pH 4 in reactive water was 0.036, 0.016, 0.010mmol/g for Pb(2+), Cd(2+), and Cu(2+), respectively, and it decreased for Pb(2+) and Cd(2+) in clarified water. Conversely, experiments carried out in clarified water showed that the cadmium adsorption capacity of chitosan was enhanced about three times by the presence of NOM at pH 7: an adsorption mechanism was proposed. Furthermore, it was found that the biosorbent selectivity, in both reactive and clarified water at pH 4, was as follows Cu(2+)>Cd(2+)>Pb(2+). Finally, the preliminary desorption experiments of Cd(2+) conducted at pH 2 and 3 reported 68 and 44.8% of metal desorbed, which indicated that the adsorption mechanism occurred by electrostatic interactions and covalent bonds.     

Adsorptive features of poly(glycidyl methacrylate-<Emphasis Type="Italic">co</Emphasis>-hydroxyethyl methacrylate): effect of porogen formulation on heavy metal ion adsorption

Preparation of crosslinked copolymer beads based on glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (HEMA), and divinyl benzene for the use of heavy metal adsorption has been investigated. In our study, a series of porous copolymer beads were synthesized by suspension polymerization in the presence of porogens, 1-dodecanol, toluene, and heptane at different dilutions. The effect of the porogens on the surface appearance and the porous structure of copolymer beads was studied by scanning electron microscopy and BET method. Diethylene triamine chelating copolymers were obtained through a reaction between amine groups of diethylene triamine and epoxide pendant groups of GMA. Adsorption isotherm and quantitative analysis for adsorption capacity involving copper, chromium, manganese, cadmium, iron, and zinc ions were investigated using atomic absorption spectrophotometer. The adsorption was a function of types of metal ions, adsorption time, and solution properties including pH and metal concentration. Adsorption equilibrium was achieved in approximately 50 min with a maximum adsorption capacity at pH 5.0. The Langmuir isotherm was found to be well fitted on the adsorption behavior. The maximum metal adsorption capacities in single ion solution in mole basis were in the order Cu(II) > Cr(VI) > Mn(II) > Zn(II) > Cd (II) > Fe(II). It was found that introducing porogen in the polymerization mixture produced the copolymer beads with better adsorption capacity. The maximum Cu(II) adsorption capacity of chelating poly(GMA-co-HEMA) beads were 1.35 mmol/g (85.79 mg/g) measured from the beads prepared in the presence of 1-heptane with 50% dilution. Consecutive adsorption–desorption experiments showed that crosslinked poly(GMA-co-HEMA) micro-beads can be reused almost without any change in the adsorption capacity.