Effect of sorbed nonylphenol on sorption of phenanthrene onto mineral surface

The effect of sorbed nonylphenol (NP) at low levels on phenanthrene sorption onto the mineral surfaces (organic-removed sediment, kaolinite) and a natural sediment with low organic content was investigated in this study. NP could be sorbed on the sediment and the minerals, and part of sorbed NP interacted with the solid surface stably. At very low concentrations, sorbed NP was observed to inhibit the sorption of phenanthrene on the hydrophilic mineral surfaces (organic-removed sediment and kaolinite) based on the change of phenanthrene apparent solid-liquid distribution coefficients. When the amount of sorbed NP increased to higher levels, enhancement of phenanthrene sorption occurred. Similar result was also obtained in isotherm experiments. On the mineral sorbents contacting with 1.0 mg/L NP solution previously, the K(d) values were lower compared with those on the sorbents without sorbed NP. On the sorbents with higher levels of sorbed NP (contacting with 10 mg/L NP solution previously), the K(d) values increased, while the isotherm tended to be more nonlinear. Concentrations of sorbed NP determined its orientation on the surface, which could presumably affect the water film above the sorbents, or contribute more adsorption sites for phenanthrene.     

Untreated coffee husks as biosorbents for the removal of heavy metals from aqueous solutions

The objective of this work was to propose an alternative use for coffee husks (CH), a coffee processing residue, as untreated sorbents for the removal of heavy metal ions from aqueous solutions. Biosorption studies were conducted in a batch system as a function of contact time, initial metal ion concentration, biosorbent concentration and pH of the solution. A contact time of 72 h assured attainment of equilibrium for Cu(II), Cd(II) and Zn(II). The sorption efficiency after equilibrium was higher for Cu(II) (89-98% adsorption), followed by Cd(II) (65-85%) and Zn(II) (48-79%). Even though equilibrium was not attained in the case of Cr(VI) ions, sorption efficiency ranged from 79 to 86%. Sorption performance improved as metal ions concentrations were lowered. The experimental sorption equilibrium data were fitted by both Langmuir and Freundlich sorption models, with Langmuir providing the best fit (R2>0.95). The biosorption kinetics was determined by fitting first and second-order kinetic models to the experimental data, being better described by the pseudo-second-order model (R2>0.99). The amount of metal ions sorbed increased with the biosorbent concentration in the case of Cu(II) and Cr(VI) and did not present significant variations for the other metal ions. The effect of the initial pH in the biosorption efficiency was verified in the pH range of 4-7, and the results showed that the highest adsorption capacity occurred at distinct pH values for each metal ion. A comparison of the maximum sorption capacity of several untreated biomaterial-based residues showed that coffee husks are suitable candidates for use as biosorbents in the removal of heavy metals from aqueous solutions.     

Ammonia removal from leachate solution using natural Chinese clinoptilolite

This paper assesses the potential of natural Chinese clinoptilolite for ammonia removal from the leachate solution of sewage sludge. In batch study the effects of relevant parameters, such as contact time, initial ammonia concentration and particle size of clinoptilolite, were examined respectively. The results show that the data obtained from batch studies were fit to Langmuir and Freundlich isotherms and the Langmuir isotherms reflect more reasonable for ammonium ion uptake onto clinoptilolite; the clinoptilolite adsorption process has been proved effective, at laboratory scale, the maximum adsorption capacity of the clinoptilolite, for ammonium concentration ranging from 11.12 to 115.16 mg NH(4)-N L(-1) in leachate solution, was about 1.74 mg NH(4)-Ng(-1); the time to adsorption equilibrium was 2.5 h in leachate solution and 1.5 h more than for in NH(4)Cl synthetic solution; ammonium adsorption increased with decreasing clinoptilolite particle size; the ammonia removal capacity of clinoptilolite increased with increasing initial ammonia concentration. It is believed that as adsorption agent for NH(4)-N removal from sludge leachate, natural Chinese clinoptilolite can be feasible.     

Equilibrium, kinetic and sorber design studies on the adsorption of Aniline blue dye by sodium tetraborate-modified Kaolinite clay adsorbent

Raw Kaolinite clay obtained Ubulu-Ukwu, Delta State of Nigeria and its sodium tetraborate (NTB)-modified analogue was used to adsorb Aniline blue dye. Fourier transformed infrared spectra of NTB-modified Kaolinite suggests that modification was effective on the surface of the Kaolinite clay with the strong presence of inner -OH functional group. The modification of Kaolinite clay raised its adsorption capacity from 1666 to 2000 mg/kg. Modeling adsorption data obtained from both unmodified and NTB-modified Kaolinite clay reveals that the adsorption of Aniline blue dye on unmodified Kaolinite clay is on heterogeneous adsorption sites because it followed strongly the Freundlich isotherm equation model while adsorption data from NTB-modified Kaolinite clay followed strongly the Langmuir isotherm equation model which suggest that Aniline blue dye was adsorb homogeneous adsorption sites on the NTB-modified adsorbent surface. There was an observed increase in the amount of Aniline blue adsorbed as initial dye concentration was increased from 10 to 30 mg/L. It was observed that kinetic data obtained generally gave better robust fit to the second-order kinetic model (SOM). The initial sorption rate was found to increased with increasing initial dye concentration (from 10 to 20 mg/L) for data obtained from 909 to 1111 mg kg(-1)min(-1) for unmodified and 3325-5000 mg kg(-1) min(-1) for NTB-modified adsorbents. Thereafter there was a decrease in initial sorption rate with further increase in dye concentration. The linearity of the plots of the pseudo-second-order model with very high-correlation coefficients indicates that chemisorption is involved in the adsorption process. From the design of a single-batch adsorber it is predicted that the NTB-modified Kaolinite clay adsorbent will require 50% less of the adsorbent to treat certain volumes of wastewater containing 30 mg/L of Aniline blue dye when it is compared with the unmodified adsorbent. This will be cost effective in the use of NTB-modified adsorbent for the adsorption of Aniline blue dye from water and wastewater.     

The adsorption kinetics and removal of cationic dye, Toluidine Blue O, from aqueous solution with Turkish zeolite

Clinoptilolite, a natural zeolite, was investigated as an inexpensive and effective adsorbent for the adsorption of Toluidine Blue O (TBO) from its aqueous solution. The effect of parameters such as the initial concentration of TBO, the solution of pH, contact time, temperature and particle size on the TBO adsorption was examined. The adsorption rate data were analysed according to the first and second-order kinetic models. Kinetic studies show that adsorption of TBO on clinoptilolite was fitted to the second-order adsorption model with two-step diffusion process. The activation energies for TBO adsorption on clinoptilolite for the first and second diffusion processes were 8.72 kJ mol(-1) and 19.02 kJ mol(-1), respectively. The adsorption isotherm was well fitted to both the Langmuir and Freundlich models. The maximum adsorption capacity of clinoptilolite for TBO was 2.1x10(-4) mol g(-1) at solution pH of 11.0.     

Adsorption of As(V) on surfactant-modified natural zeolites

Natural mordenite (NM), natural clinoptilolite (NC), HDTMA-modified natural mordenite (SMNM) and HDTMA-modified natural clinoptilolite (SMNC) have been proposed for the removal of As(V) from aqueous solution (HDTMA=hexadecyltrimethylammonium bromide). Influence of time on arsenic sorption efficiency of different sorbents reveals that NM, NC, SMNM and SMNC require about 20, 10, 110 and 20h, respectively to reach at state of equilibrium. Pseudo-first-order model was applied to evaluate the As(V) sorption kinetics on SMNM and SMNC within the reaction time of 0.5h. The pseudo-first-order rate constants, k are 1.06 and 0.52h(-1) for 1 and 0.5g of SMNM, respectively. The observed k values 1.28 and 0.70h(-1) for 1 and 0.5g of SMNC, respectively are slightly high compared to SMNM. Surfactant surface coverage plays an important role and a significant increase in arsenate sorption capacity could be achieved as the HDTMA loading level on zeolite exceeds monolayer coverage. At a surfactant partial bilayer coverage, As(V) sorption capacity of 97.33 and 45.33mmolkg(-1) derived from Langmuir isotherm for SMNM and SMNC, respectively are significantly high compared to 17.33 and 9.33mmolkg(-1) corresponding to NM and NC. The As(V) uptake was also quantitatively evaluated using the Freundlich and Dubinin-Kaganer-Radushkevich (DKR) isotherm models. Both SMNM and SMNC removed arsenic effectively over the initial pH range 6-10. Desorption performance of SMNM and SMNC were 66.41% and 70.04%, respectively on 0.1M NaOH regeneration solution.     

On the zinc sorption by the Serbian natural clinoptilolite and the disinfecting ability and phosphate affinity of the exhausted sorbent

The Serbian natural zeolite is moderately effective in removing the zinc(II) ions from aqueous solutions. At 298 K the sorption capacity varies from 13 to 26% for the initial Zn(II) solution concentration of 100 and 600 mg Zndm(-3), respectively. The sorption isotherm at 298-338 K is best represented by the Langmuir model and the sorption kinetics by the pseudo-second-order model. The sorption involves a combination of film diffusion, intra-particle diffusion, and a chemical cation-exchange between the Na(+) ions of clinoptilolite and Zn(2+) ions. The sorption was found to be endothermic and spontaneous in the 298-338 K range. The exhausted sorbent can remove phosphate ions and it exhibits an excellent antibacterial activity towards Acinetobacter junii. By dehydration at about 500 °C it transforms to a ZnO-containing product featuring nano-sized wurtzite ZnO particles widespread over the clinoptilolite surface.     

Temperature-jump investigation of alkyl chain length effects on sorption/desorption kinetics at reversed-phase chromatographic interfaces

The influence of the alkyl chain length on the kinetics of solute retention at reversed-phase chromatographic surfaces is examined. A Joule-discharge temperature-jump relaxation experiment was used to monitor reversible sorption/desorption kinetics at C4- and C8-modified silica/solution interfaces. Biexponential sorption/desorption relaxation kinetics were observed for a charged fluorescent probe, 1-anilino-8-naphthalenesulfonate (ANS), on both C4- and C8-silica surfaces. Both relaxation rates on C4 surfaces were sufficiently slow to be measured and increased linearly with solute concentration. One of the relaxations on a C8 surface is too fast to be resolved from the heating rate, similar to behavior of the solute on a longer chain C18-silica. These observations suggest that sorption kinetics on the intermediate chain length surfaace, C4-silica, are different from kinetics on longer chain length surfaces, C8- and C18-silica. From a fit of the data to a two-step kinetic model, the rates of both adsorption and partition of the ionic probe on the C4 chain are estimated; both rates exhibit significant influence over the equilibrium constant. The relaxation rate of a neutral probe, N-phenyl-1-naphthylamine, is also measured; the results indicate a fast (diffusion-controlled) adsorption step, followed by a detectable barrier to partition that is similar to the partition barrier for ANS on the C4-silica surface. These results show that the alkyl chain length of modified silica strongly influences retention kinetics.     

沸石粉体对胆固醇型人体胆结石体外吸附研究

为研究沸石粉体对胆固醇型人体胆结石体外吸附的可能性,采用SEM观察了胆固醇型人体胆结石的表面形貌;利用IR对其化学组成进行了分析,并根据天然斜发沸石所具有的较强吸附性能,分别研究了天然沸石粉体和盐酸活化沸石粉体对胆固醇型人体胆结石的体外吸附行为。结果表明:在体外环境下两种沸石对胆固醇型人体胆结石均有一定的吸附能力,但后者吸附效果较前者差,其吸附机理有待进一步深入研究。     

Removal of malachite green by using an invasive marine alga Caulerpa racemosa var. cylindracea

The biosorption of a cationic dye, malachite green oxalate (MG) from aqueous solution onto an invasive marine alga Caulerpa racemosa var. cylindracea (CRC) was investigated at different temperatures (298, 308 and 318 K). The dye adsorption onto CRC was confirmed by FTIR analysis. Equilibrium data were analyzed using Freundlich, Langmuir and Dubinin-Radushkevich (DR) equations. All of the isotherm parameters were calculated. The Freundlich model gave a better conformity than Langmuir equation. The mean free energy values (E) from DR isotherm were also estimated. In order to clarify the sorption kinetic, the fit of pseudo-first-order kinetic model, second-order kinetic model and intraparticle diffusion model were investigated. It was obtained that the biosorption process followed the pseudo-second-order rate kinetics. From thermodynamic studies the free energy changes were found to be -7.078, -9.848 and -10.864 kJ mol(-1) for 298, 308 and 318 K, respectively. This implied the spontaneous nature of biosorption and the type of adsorption as physisorption. Activation energy value for MG sorption (E(a)) was found to be 37.14 kJ mol(-1). It could be also derived that this result supported physisorption as a type of adsorption.     

Clinoptilolite/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>: a magnetic sorbent for removing <Superscript>90</Superscript>Sr from aqueous media

The ability of a magnetic sorbent prepared by modification of clinoptilolite with magnetite to take up ⁹⁰Sr was studied. ⁹⁰Sr is sorbed most efficiently at pH in the range 6–9. At the sorbent dosage of 5 g dm^–3 and sorption time of 24 h, the degree of ⁹⁰Sr sorption from aqueous solution is as high as 99.8%.     

Utilization of barley straws as biosorbents for Cu2+ and Pb2+ ions

The potential to remove Cu(2+) and Pb(2+) ion from aqueous solutions through biosorption using barley straw (BS) was investigated in batch experiments. The main parameters influencing Cu(2+) and Pb(2+) ion sorption on BS were: initial metal ion concentration, amount of adsorbent, contact time and pH value of solution. The influences of initial Cu(2+) and Pb(2+) ion concentration (0.1-1mM), pH (2-9), contact time (10-240 min) and adsorbent amount (0.1-1.0 g) have been reported. Equilibrium isotherms have been measured and modelled. The percent adsorption of Cu(2+) and Pb(2+) ions increased with an increase in pH and dosage of treated BS. The biosorptive capacity of the BS was dependent on the pH of Cu(2+) and Pb(2+) ion solution. Adsorption of Cu(2+) and Pb(2+) ion was in all cases pH dependent showing a maximum at equilibrium pH value at 6.0. The equilibrium sorption capacities of Cu(2+) and Pb(2+) after 2h were 4.64 mg/g and 23.20mg/g for BS, respectively. The adsorption data fit well with the Langmuir isotherm model and the experimental result inferred that complexation on surface, adsorption (chemisorption) and ion exchange is one of the major adsorption mechanisms for binding Cu(2+) and Pb(2+) ion to the sorbents.     

Adsorption of chlorinated hydrocarbon vapors onto soil in the presence of water

Chlorinated solvents partition readily into the vapor-phase in unsaturated soils. Sorption from the vapor-phase affects both transport and recovery. The Brunauer-Emmett-Teller (BET) isotherm has been used to model adsorption of chlorinated solvent vapors; however, the BET equation is not accurate above reduced vapor pressures (p/p(sat)) of 0.35. New measurements of chlorinated alkane sorption have been used with a modified BET equation (MBET) to model the adsorption isotherms for five solvents. The MBET equation was found to fit experimental data accurately, especially at high reduced vapor pressures. The capacity of sandy loam soil to adsorb organic vapors decreased with increasing water content, probably due to less soil surface available for sorption. This effect is most evident at reduced vapor pressures greater than 0.5. Adsorption is related to distribution of excess surface energy, the number of molecular layers of water sorbed at the surface, and solute polarity. Results suggest that water films contain areas of high interfacial energy that interact with solute molecules via induced electrostatic forces.     

The removal of Basic Blue 3 from aqueous solutions by chitosan-based adsorbent: batch studies

Chitosan-based adsorbent (CHITOD material) is used for the removal of Basic Blue 3 (BB 3) from aqueous solutions. The adsorption of BB 3 on CHITOD material was studied as a function of time, sorbent mass and concentration. The influence of these parameters on the adsorption capacity was evaluated using the batch method. Results of adsorption experiments and kinetic data showed that (i) the CHITOD adsorbent exhibited high sorption capacities toward BB 3; (ii) the Langmuir equation represented the best fit of experimental data; (iii) the dye sorption on material was exothermic and spontaneous in nature; (iv) the kinetic measurements showed that the process was rapid; (v) the adsorption kinetics followed a pseudo-second order model; and (vi) the sorption was dependent on the presence of sulfonate groups. Non-linear method was also found to be more appropriate method for estimating the isotherm and kinetic parameters.     

Treatment of wastewater containing toxic chromium using new activated carbon developed from date palm seed

The use of a new activated carbon developed from date palm seed wastes, generated in the jam industry, for removing toxic chromium from aqueous solution has been investigated. The activated carbon has been achieved from date palm seed by dehydrating methods using concentrated sulfuric acid. The batch experiments were conducted to determine the adsorption capacity of the biomass. The effect of initial metal concentration (25-125mgl(-1)), pH, contact time, and concentration of date palm seed carbon have been studied at room temperature. A strong dependence of the adsorption capacity on pH was observed, the capacity increase as pH value decrease and the optimum pH value is pH 1.0. Kinetics and adsorption equilibrium were studied at different sorbent doses. The adsorption process was fast and the equilibrium was reached within 180min. The maximum removal was 100% for 75mgl(-1) of Cr(+ concentration on 4gl(-1) carbon concentration and the maximum adsorption capacity was 120.48mgg(-1). The kinetic data were analyzed using various kinetic models - pseudo-first order equation, pseudo-second order equation, Elovich equation and intraparticle diffusion equation - and the equilibrium data were tested using several isotherm models, Langmuir, Freundlich, Koble-Corrigan, Redlich-Peterson, Tempkin, Dubinin-Radushkevich and Generalized isotherm equations. The Elovich equation and pseudo-second order equation provide the greatest accuracy for the kinetic data and Koble-Corrigan and Langmuir models the closest fit for the equilibrium data. Activation energy of sorption has also been evaluated as 0.115 and 0.229kJmol(-1).     

Adsorption kinetics and modeling of gadolinium and cobalt ions sorption by an ion-exchange resin

ABSTRACT

In this work, the removal of gadolinium and cobalt ions using Dowex HCR-S/S resin was studied. Batch-mode kinetic and equilibrium studies have been carried out. The effect of solution pH, shaking time, initial metal ion concentrations, resin dosage and temperature has been investigated. Equilibrium data were analyzed by sorption isotherm models. The results of sorption experiments indicate that the monolayer capacities of Gd(III) and Co(II) at equilibrium are 66.0 and 69.4 mg/g, respectively. The results of kinetic models showed that the pseudo-second-order kinetic model was found to correlate with the experimental data well. It was found that the amount of ions sorbed onto the resin increased with increasing temperature; this indicates the endothermic nature of the sorption process. It was concluded that resin has an efficient sorption capacity compared to many sorbents.     

Sorption behavior of cesium on various soils under different pH levels

In the present study we investigated the sorption behavior of Cs in four different soils (sandyloam, loam, clayloam and clay) by using batch experiment. Cs sorption characteristics of the studied soils were examined at 4 mgL(-1) Cs concentration, at various pH levels, at room temperature and with 0.01 M CaCl(2) as a background electrolyte. Among different soils the decrease of k(d) (distribution coefficient) of cesium, at all pH levels, followed the sequence sandyloam > loam > clayloam > clay, indicating that the particle size fractions and especially the clay content plays predominant role on sorption of Cs. The effect of pH on cesium sorption displays a similar pattern for all soils, depending on soil type. At acid pH levels less cesium was sorbed, due to a greater competition with other cations for available sorption sites. The maximum sorption of Cs was observed at pH 8, where the negative charge density on the surface of the absorbents was the highest. For all soils was observed significantly lower Cs sorption at pH 10.     

p-Nitrophenol, phenol and aniline sorption by organo-clays

The aims of this study were to make use of organo-clays (i.e., Cloisite-10A, Cloisite-15A, Cloisite-30B and Cloisite-93A), to remove p-nitrophenol, phenol and aniline of organic pollutants. The organo-clays were characterized by X-ray diffraction (XRD). Sorption isotherm, kinetic and pH effect of p-nitrophenol, phenol and aniline sorbed by four organo-clays were evaluated. The d-spacings (001) of the XRD peak of Cloisite-10A, Cloisite-15A, Cloisite-30B and Cloisite-93A are 1.98, 2.76, 1.93 and 2.64 nm, respectively. The d(001)-spacings of XRD indicated that these p-nitropheno, phenol and aniline could penetrate into the interlayer of clays and expand the d(001)-spacings. The linear sorption isotherm of constant partition was employed to describe the sorption isotherms of phenols sorbed by organo-clays through hydrophobic-hydrophobic chemical reactions. The parabolic diffusion and power-function of kinetic models were employed to describe properly the kinetic experiments. The rate limiting step of the p-nitrophenol sorption reactions on organo-clays were diffusion-controlled processes (i.e., 15A, 30B, 93A) and chemical-controlled process for 10A organo-clays. The pre-exponential factor of the p-nitrophenol sorbed by four organo-clays showed the trend as follows: 10A> 30B> 93A> 15A. The efficiency of these organo-clays in removing phenol compounds in water treatments merit further study.     

Sorption of Cd(II) onto kaolin as a soil component and desorption of Cd(II) from kaolin using rhamnolipid biosurfactant

In this study, a microbial surfactant, rhamnolipid, was investigated for its potential to enhance recovery of Cd(II) from kaolin, a representative soil component. The study was divided into two parts. In the first part, the sorption of Cd(II) ions to kaolin was investigated as a function of pH and initial Cd(II) ion concentration. Kaolin was also shown to be a good sorbent for treatment of Cd(II) ions from waste waters. The equilibrium sorption capacity for Cd(II) ions was measured and extrapolated using the Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan sorption models. The best correlation between experimental and model predicted equilibrium uptake was obtained using the Kolbe-Corrigan sorption model. The values of parameters of the Koble-Corrigan model were determined as A=11.13 (mmol(1-b)kg(-1)L(b)); B=0.39 (L(b)mmol(-b)); b=0.48. In the second part, the desorption of Cd(II) from kaolin was investigated as a function of pH, rhamnolipid concentration, and the amount of sorbed Cd(II) by kaolin. The highest Cd(II) desorption efficiency by rhamnolipid biosurfactant from kaolin was obtained at pH 6.8, at an initial Cd(II) ion concentration of 0.87 mM (4.42 mmol Cd(II)/kg kaolin) and at a rhamnolipid concentration of 80 mM and found to be 71.9% of the sorbed Cd(II).     

Sorption of malachite green on chitosan bead

Chitosan bead was synthesized for the removal of a cationic dye malachite green (MG) from aqueous solution. The effects of temperature (303, 313 and 323 K), pH of the solution (2-11) on MG removal was investigated. Preliminary kinetic experiment was carried out up to 480 min. The sorption equilibrium was reached within 5 h (300 min). In order to determine the adsorption capacity, the sorption data were analyzed using linear form of Langmuir and Freundlich equation. Langmuir equation showed higher conformity than Freundlich equation. Ninety-nine percent removal of MG was reached at the optimum pH value of 8. From kinetic experiments, it was obtained that sorption process followed the pseudo-second-order kinetic model. This study showed that chitosan beads can be excellent adsorbents at high pH values. Activation energy value for sorption process was found to be 85.6 kJ mol(-1). This indicates that sorption process can be assumed as chemical process. Due to negative values of Gibbs free energy, sorption process can be considered as a spontaneous. In order to determine the interactions between MG and chitosan bead, FTIR analysis was also conducted.