Removal of Cu(II) and Pb(II) by Pithophora oedogonia: sorption, desorption and repeated use of the biomass

Maximum sorption of Cu(II) and Pb(II) by dried filamentous green alga Pithophora oedogonia occurred at pH 4.5 and 5.0, respectively. Chemical pretreatment could not appreciably enhance the metal sorption ability of the biomass. HCl and EDTA desorbed 92-96% of the sorbed metal from the metal-loaded biomass. Sorption and desorption of both the test metals were very rapid attaining an equilibrium within 15 min. The time course data of both the processes fitted well to the pseudo-first and the pseudo-second-order Lagergren kinetic models with r2> or =0.979. The isotherm equilibrium of Cu(II) and Pb(II) followed the Redlich-Peterson and Sips model very well with r2> or =0.991. The sorption of Cu(II) and Pb(II) at varying biomass doses could be well defined by linear and hyperbolic decrease, respectively. The regenerated biomass of Pithophora has better reusability for Pb(II) than for Cu(II). A good mechanical strength of Pithophora biomass was apparent as only 10-15% loss of biomass occurred at the end of the fifth cycle.     

Stationary-phase contribution of 1-propanol organic modifier to changes in sorption of 1-hexanol on an ODS-bonded phase

Using the reversed-phase bonded-phase HPLC packing Partisil-10 ODS-3, sorption isotherms have been measured for the alcohols 1-propanol (PrOH) and 1-hexanol (HexOH), and as well, a simultaneous sorption curve for the two alcohols has been measured from solutions containing a low and constant concentration of HexOH as sample with increasing concentrations of PrOH as organic modifier. The mobile-phase effect of PrOH is quantified by solution-phase activity coefficients obtained either from vapor/solution equilibrium measurements or from cloud point measurements. Since sorbed alcohols are located at the ODS/solution interface, the stationary-phase effect of PrOH is modeled in terms of three processes: (i) competition for space; (ii) decrease of space required per mole with increasing concentration of sorbed PrOH; and (iii) change of free energy of sorption with increasing concentration of sorbed PrOH. The model yields excellent fits to the isotherms and to the simultaneous sorption curve. Comparison of the model-fitting parameters for the simultaneous sorption curve with those for the PrOH isotherm confirms that the stationary-phase effect of PrOH on HexOH is due exclusively to processes i and ii. Sorbed PrOH causes rearrangement of the C18 chains of the ODS phase. For volume percent PrOH less than 15% in the mobile phase, the effect of PrOH on sample sorption is nearly exclusively in the stationary phase. Between 15 and 30%, both mobile- and stationary-phase effects are important.     

Effect of Stationary-Phase Sorption of Organic Modifier from a Water-Rich Mobile Phase on Solute Retention by an ODS Bonded Phase

Sorption isotherms for 1-butanol (BuOH) and eucalyptol (Eu) on Partisil 10 ODS-3 are plotted as concentration sorbed versus activity in aqueous solution. The former follows the Langmuir equation and the latter follows the equation for an "associative bilayer isotherm with limited solubility in the aqueous phase". Two series of simultaneous sorption experiments of BuOH and Eu were also performed. One series involved measuring the influence of BuOH, as an organic modifier solvent in water, on the sorption of Eu as solute. In the second series, the roles of BuOH and Eu were reversed. These studies show that when sorption is treated as partitioning between two bulk liquid phases, the stationary phase behaves as an ideal solution which is composed of C(18) chains, sorbed organic modifier, and sorbed solute. Combined with the Langmuir isotherm behavior of BuOH, this ideal solution behavior supports the view that BuOH is sorbed at the stationary-phase/mobile-phase interface, with its hydrocarbon tail in the stationary phase.     

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.     

Removal of phenol and 4-chlorophenol by surfactant-modified natural zeolite

In this study the adsorption characteristics of phenol and 4-chlorophenol by surfactant-modified zeolite was investigated. Batch studies were performed to evaluate the effects of various experimental parameters such as contact time, adsorbent dose, initial concentration, and temperature on the removal of phenol and 4-chlorophenol. The sorption kinetics was tested for intraparticle diffusion, Elovich, and pseudo-second order reaction and rate constants of kinetic models were calculated. Equilibrium isotherms for the adsorption of phenol were analyzed by Freundlich, Langmuir, and Tempkin isotherm models. Freundlich isotherm was found to best represent the data for phenol and 4-chlorophenol adsorption.     

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.     

非苯乙烯型超高交联树脂的修饰及对酚类化合物的吸附

分别通过4,4'-二氯甲基联苯与1,4'-二氟甲基苯的傅克烷基化聚合和胺化反应,制得一类比表面积可达1138 m2/g的胺基吸附树脂新材料.研究表明,这类非苯乙烯型胺基树脂对苯酚、对硝基苯酚的饱和吸附容量分别可达140 mg/g和331 mg/g,明显优于国内外用于酚类吸附的AmberliteXAD-4、H103等吸附...     

Adsorption behaviors of some phenolic compounds onto high specific area activated carbon cloth

Adsorption of phenol, hydroquinone, m-cresol, p-cresol and p-nitrophenol from aqueous solutions onto high specific area activated carbon cloth has been studied. The effect of ionization on adsorption of these ionizable phenolic compounds was examined by studying the adsorption from acidic, basic and natural pH solutions. Kinetics of adsorption was followed by in situ UV spectroscopy over a period of 90 min. First-order rate law was found to be valid for the kinetics of adsorption processes and the rate constants were determined. The highest rate constants were obtained for the adsorption from solutions at the natural pH. The lowest rate constants were observed in basic solutions. The rate constants decreased in the order p-nitrophenol approximately m-cresol>p-cresol>hydroquinone approximately phenol. Adsorption isotherms were derived at 30 degrees C and the isotherm data were treated according to Langmuir, Freundlich and Tempkin isotherm equations. The goodness of fit of experimental data to these isotherm equations was tested and the parameters of equations were determined. The possible interactions of compounds with the carbon surface were discussed considering the charge of the surface and the possible ionization of compounds at acidic, basic and natural pH conditions.     

Equilibrium and kinetic studies of methyl violet sorption by agricultural waste

In this work, sunflower (Helianthus annuus L.) seed hull (SSH), an agricultural waste, was evaluated for its ability to remove methyl violet (MV) from aqueous solutions. Sorption isotherm of MV onto the SSH was determined at 30 degrees C with the initial concentrations of MV in the range of 25-300 mg/L. The equilibrium data were analyzed using the Langmuir, Freundlich and Temkin isotherm models. The equilibrium process was described well by the Freundlich isotherm model. The maximum SSH sorption capacity was found to be 92.59 mg/L at 30 degrees C. The kinetic data were studied in terms of the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The pseudo-second-order model best described the sorption process. A single-stage batch-adsorber design of the adsorption of MV onto SSH was studied based on the Freundlich isotherm equation. The results indicated that sunflower seed hull was an attractive candidate for removing methyl violet from aqueous solution.     

Application of modified nanoporous materials in ascorbic acid adsorption

In this study, three types of mesoporous materials Santa Barbara no. 15 (SBA-15), carbon mesostructured by KAIST (CMK-3), and modified carbon mesostructured by KAIST (modified CMK-3) were prepared and their capability as sorbents for vitamin C (ascorbic acid) adsorption from aqueous solutions was compared with each other. Cetyltrimethylammonium bromide (CTAB) was used for surface modification of CMK-3. The structures of different adsorbents were characterized by X-ray diffraction (XRD) and N₂ adsorption measurements, and the functionalization of CMK-3 was proved by XRD technique. The adsorption isotherms, sorption kinetics as well as the effects of some parameters such as pH value of the vitamin solution, adsorption time, and the initial vitamin concentration on the adsorption capacity of the analyte on CTAB/CMK-3 were investigated. It was found that the ultimate capacity of the adsorbents varied in the order CTAB/CMK-3?>?CMK-3?>?SBA-15. Langmuir and Freundlich isotherm models have been used to fit equilibrium data for CTAB/CMK-3. The equilibrium data were best represented by the Langmuir isotherm. Kinetic studies were performed and it was determined that the sorption kinetics of vitamin C was truly described by a pseudo-second-order kinetic model.     

Clinoptilolite in study of lindane and aldrin sorption processes from water solution

The scope of this study was adsorption of lindane and aldrin from water solution onto clinoptilolite rock with the following desorption using n-hexane. Both kinetic and equilibrium tests were conducted. During kinetic experiment the most part of aldrin and a half part of lindane were sorbed during the first hours. The sorption equilibria with removal of 95% of aldrin amount and about 68% of lindane amount have been set in for 48 h. The pseudo-second-order kinetics model gives somewhat better fit to the both pesticides' sorption data that may testify to the complicated and heterogeneous nature of interaction between active zeolite surface and the pesticides polar-dipole centers. OH(-)-groups and the coordinated exchangeable cations are probably the main active positions for the pesticide sorption on the clinoptilolite surface. Equilibrium experiment results show that adsorption isotherms for the low concentrations of lindane and aldrin (10-200 and 3-100 microg/L, respectively) fit well to the Freundlich and the Liner models. Only 10% of lindane sorbed and about 60% of aldrin sorbed were desorbed from the clinoptilolite using n-hexane under static conditions.     

Equilibrium, kinetics and mechanism modeling and simulation of basic and acid dyes sorption onto jute fiber carbon: Eosin yellow, malachite green and crystal violet single component systems

Batch experiments were carried out for the sorption of eosin yellow, malachite green and crystal violet onto jute fiber carbon (JFC). The operating variables studied are the initial dye concentration, initial solution pH, adsorbent dosage and contact time. Experimental equilibrium data were fitted to Freundlich, Langmuir and Redlich-Peterson isotherm by non-linear regression method. Langmuir isotherm was found to be the optimum isotherm for eosin yellow/JFC system and Freundlich isotherm was found to be the optimum isotherm for malachite green/JFC and crystal violet/JFC system at equilibrium conditions. The sorption capacities of eosin yellow, malachite green and crystal violet onto JFC according to Langmuir isotherm were found to 31.49 mg/g, 136.58 mg/g, 27.99 mg/g, respectively. A single stage batch adsorber was designed for the adsorption of eosin yellow, malachite green and crystal violet onto JFC based on the optimum isotherm. A pseudo second order kinetic model well represented the kinetic uptake of dyes studied onto JFC. The pseudo second order kinetic model successfully simulated the kinetics of dye uptake process. The dye sorption process involves both surface and pore diffusion with predominance of surface diffusion at earlier stages. A Boyd plot confirms the external mass transfer as the rate limiting step in the dye sorption process. The influence of initial dye concentration on the dye sorption process was represented in the form of dimensionless mass transfer numbers (Sh/Sc(0.33)) and was found to be agreeing with the expression:     

A comparative study for the sorption of Cd(II) by soils with different clay contents and mineralogy and the recovery of Cd(II) using rhamnolipid biosurfactant

Recent research has demonstrated that biosurfactants, especially rhamnolipids, can enhance recovery of soil-bound metals. To propose the success of remediation process of soils by rhamnolipids, both sorption and desorption characteristics of soils having different clay mineralogy should be known exactly. To assess sorption of Cd(II), batch equilibrium experiments were performed using three soils characterized with different proportions of clay minerals from Eski?ehir region of Turkey. Soil pH, initial metal concentration and clay mineralogy affected the sorption process. For comparisons between soils, the sorption process was characterized using the Langmuir, Freundlich, Redlich-Peterson, Koble-Corrigan sorption models. The Freundlich model showed the best fit for the Cd(II) sorption data by the soils, while the Langmuir-type models generally failed to describe the sorption data. Soils with higher clay content characterized by having smectite as a dominant component had the greatest sorption capacity and intensity estimated by the KF and n parameters of the Freundlich model. The soil C has the highest sorption efficiency of 83.9%, followed by soils B and A with sorption efficiencies of 76.7% and 57.9%, respectively. After the soils were loaded by different doses of Cd(II), batch washing experiments were used to evaluate the feasibility of using rhamnolipid biosurfactant for the recovery of Cd(II) from the soils. The Cd(II) recovery of the soils were investigated as a function of pH, amount of Cd(II) loaded to the soils, and rhamnolipid concentration. Cd(II) recovery efficiencies from the soils using rhamnolipid biosurfactant decreased in the order of soil A>soil B>soil C. This order was the reverse of the Cd(II) sorption efficiency order on the soils. When 80 mM rhamnolipid was used, the recovery efficiencies of Cd(II) from the soils A, B, and C was found to be 52.9%, 47.7%, 45.5% of the sorbed Cd(II), respectively. Rhamnolipid sorption capacity of the soils in the presence of Cd(II) ions decreased in the order of soil A>soil B>soil C.     

Uptake of permanganate from aqueous environment by surfactant modified montmorillonite batch and fixed bed studies

Organo-clay was prepared by incorporating different amounts (in terms of CEC, ranging from 134?C840 mg of quaternary ammonium cation (QACs) such as hexadecytrimethylammonium bromide ([C₁₉H₄₂N]Br) into the montmorillonite clay. Prepared organo-clays are characterized by CHN analyser and XRD to measure the amount of elemental content and interlayer spacing of surfactant modified clay. The batch experiments of sorption of permanganate from aqueous media by organo-clays was studied at different acidic strengths (pH 1?C7). The experimental results show that the rate and amount of adsorption of permanganate was higher at lower pH compared to raw montmorillonite. Laboratory fixed bed experiments were conducted to evaluate the breakthrough time and nature of breakthrough curves. The shape of the breakthrough curves shows that the initial cationic surfactant loadings at 1??0 CEC of the clay is enough to enter the permanganate ions in to the interlamellar region of the surfactant modified smectile clays. These fixed bed studies were also applied to quantify the effect of bed-depth and breakthrough time during the uptake of permanganate. Calculation of thermodynamic parameters shows that the sorption of permanganate is spontaneous and follows the first order kinetics.     

改性膨润土的制备及其对苯胺的吸附性能

采用十六烷基三甲基溴化铵和壳聚糖季铵盐协同对钠基膨润土进行改性,制备了一种新型的吸附剂。研究了改性膨润土吸附苯胺的机理及其主要影响因素。实验结果表明,改性膨润土对苯胺的吸附几乎不受吸附温度和溶液酸碱性影响;并在较短的时间内到达吸附平衡。外加无机盐可促进改性土对苯胺的吸附,吸附过程遵循准二阶动力学模型。改性土适合处理高浓度苯胺溶液。当苯胺质量浓度为3 000mg/L时,其吸附容量达29.7mg/g。改性土对苯胺的吸附符合Freundlich等温吸附模式,吸附机制主要是分配作用。     

The influence of DTABr surfactant on the electrokinetic and rheological properties of soda-activated bentonite dispersions

The influence of the cationic surfactant dodecyltrimethylammonium bromide (DTABr) on the electrokinetic and rheological properties of a soda-activated bentonite was investigated. The electrokinetic and rheological measurements of the surfactant-bentonite (2 wt.%) system were performed at three pH values of 4, 8 and 12. The electrokinetic measurement results show that the DTABr was adsorbed on the bentonite mostly at pH 4 and 8, whereas X-ray diffraction (XRD) studies revealed that the DTABr surfactant enters the interlamellar space of the clay mineral at pH 8 and 12. Rheological data showed that the flow behavior changed with the surfactant concentration. The basal d₍₀₀₁₎-spacings of DTABr-treated bentonite samples revealed expandability, from 14.8 to 16.8 Å. XRD results indicate a monolayer arrangement of the DTABr molecules parallel to the silicate layer.     

Arsenic sorption onto natural hematite, magnetite, and goethite

In this work the sorption of As(III) and As(V) on different natural iron oxides (hematite, magnetite, and goethite) has been studied as a function of different parameters. The sorption kinetics for the three iron oxides shows that equilibrium is reached in less than 2 days and the kinetics of sorption seems to be faster for goethite and magnetite than for hematite. The variation of the arsenic sorbed on the three different sorbents as a function of the equilibrium arsenic concentration in solution has been fitted with a non-competitive Langmuir isotherm. The main trend observed in the variation of the arsenic sorbed with pH is the decrease of the sorption on the three sorbents at alkaline pH values, which agrees with results found in the literature. Highest As(III) sorption was observed on hematite surface in all the pH range compared to goethite and magnetite. Natural minerals studied in this work had similar sorption capacities for arsenic than synthetic sorbents.     

Removal of phenol from aqueous solutions by adsorption onto activated carbon prepared from biomass material

Activated carbon derived from rattan sawdust (ACR) was evaluated for its ability to remove phenol from an aqueous solution in a batch process. Equilibrium studies were conducted in the range of 25–200 mg/L initial phenol concentrations, 3–10 solution pH and at temperature of 30 °C. The experimental data were analyzed by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. Equilibrium data fitted well to the Langmuir model with a maximum adsorption capacity of 149.25 mg/g. The dimensionless separation factor R_L revealed the favorable nature of the isotherm of the phenol-activated carbon system. The pseudo-second-order kinetic model best described the adsorption process. The results proved that the prepared activated carbon was an effective adsorbent for removal of phenol from aqueous solution.     

Mechanism of p-nitrophenol adsorption from aqueous solution by HDTMA+-pillared montmorillonite--implications for water purification

HDTMA+-pillared montmorillonites were obtained by pillaring different amounts of the surfactant hexadecyltrimethylammonium bromide (HDTMAB) into sodium montmorillonite (Na-Mt) in an aqueous solution. The optimum conditions and batch kinetics of sorption of p-nitrophenol from aqueous solutions are reported. The solution pH had a very important effect on the sorption of p-nitrophenol. The maximum p-nitrophenol absorption/adsorption occurs when solution pH (7.15-7.35) is approximately equal to the pKa (7.16) of the p-nitrophenol ion deprotonation reaction. X-ray diffraction analysis showed that surfactant cations had been pillared into the interlayer and the p-nitrophenol affected the arrangement of surfactant. With the increased concentration of surfactant cations, the arrangement of HDTMA+ within the clay interlayer changes and the sorption of p-nitrophenol increases. HDTMA+-pillared montmorillonites are more effective than Na-Mt for the adsorption of p-nitrophenol from aqueous solutions. The Langmuir, Freundlich and dual-mode sorption were tested to fit the sorption isotherms.