Removal of anionic surfactants from aqueous solutions by adsorption onto high area activated carbon cloth studied by in situ UV spectroscopy

The removal of anionic surfactants, benzene sulfonate (BS), p-toluene sulfonate (TS), 4-octylbenzene sulfonate (OBS) and 4-dodecylbenzene sulfonate (DBS) from water and 0.01 M H(2)SO(4) solutions by adsorption onto high area activated carbon cloth (ACC) were studied by in situ UV-spectroscopic technique. The various properties of the ACC were given and the in situ UV-spectroscopic technique was described. Both kinetic and isotherm data were obtained for the adsorption of surfactants. Kinetic data were treated according to intraparticle diffusion, pseudo-first-order, pseudo-second-order and Elovich models. They were found to fit the pseudo-second-order model best. Isotherm data were treated according to well-known Langmuir and Freundlich models. The regression analysis of the data showed that Freundlich model represents the isotherm data of the surfactants better. The rate and extent of adsorption of surfactants were found to increase in the order BS相似文献   

Kinetic and equilibrium studies on the removal of acid dyes from aqueous solutions by adsorption onto activated carbon cloth

Removal of acid dyes Acid Blue 45, Acid Blue 92, Acid Blue 120 and Acid Blue 129 from aqueous solutions by adsorption onto high area activated carbon cloth (ACC) was investigated. Kinetics of adsorption was followed by in situ UV-spectroscopy and the data were treated according to pseudo-first-order, pseudo-second-order and intraparticle diffusion models. It was found that the adsorption process of these dyes onto ACC follows the pseudo-second-order model. Adsorption isotherms were derived at 25 degrees C on the basis of batch analysis. Isotherm data were treated according to Langmuir and Freundlich models. The fits of experimental data to these equations were examined.     

Enhanced adsorption of phenol from water by ammonia-treated activated carbon

Influence of treatment with gaseous ammonia on adsorption properties toward phenol from water was examined for commercially available CWZ-series activated carbons. The treatment was carried out at elevated temperatures ranged from 400 degrees C to 800 degrees C for 2 h. In comparison with untreated material, activated carbons modified with ammonia demonstrated enhanced adsorption of phenol from water. The enhancement depended on the treatment temperature and porous structure of studied activated carbons. Fourier transform infrared spectroscopy (FTIR) measurements confirmed presence of N-containing species in ammonia-treated activated carbons. Optimal conditions of the modification with ammonia were determined. Influence of the N-containing groups and porous structure of activated carbons on adsorption of phenol is discussed.     

KOH活化碳气凝胶对水中亚甲基蓝的吸附性能研究

以间苯二酚和甲醛为原料水热制备有机气凝胶,在碳化过程中使用KOH作活化剂制备出孔结构丰富的碳气凝胶。采用扫描电镜(SEM)、X射线衍射(XRD)及N2吸脱附法等手段对材料的结构及形貌表征,考察了活化剂用量、染料初始浓度、接触时间等因素对亚甲基蓝在碳气凝胶上吸附的影响,并进行了吸附类型和吸附动力学研究。结果表明:活化剂的加入使碳气凝胶材料的孔结构更加丰富,当活化剂与有机气凝胶的质量比达到2∶1时,其吸附性能最佳。碳气凝胶去除亚甲基蓝的吸附行为符合二级动力学模型。吸附类型为Langmuir吸附模型。     

Analysis of adsorption characteristics of 2,4-dichlorophenol from aqueous solutions by activated carbon fiber

In this study experiments were conducted to investigate the adsorption of 2,4-dichlorophenol (2,4-DCP) by activated carbon fiber (ACF) activated by static air. With the results of batch experiments at various temperatures, the adsorption isotherms, kinetics and thermodynamics of this adsorption process were evaluated. Four adsorption isotherm models, Langmuir, Freundlich, Redlich-Peterson and Toth equations, were used to fit the experimental data and the results reveal that the adsorption isotherm models fitted the data in the order of: Langmuir>Redlich-Peterson>Toth>Freundlich isotherms. A pseudo second-order adsorption model was better to describe the adsorption data than the pseudo first-order model and the Bangham model at the temperatures tested. The activation energy was calculated to be 40.90 kJ/mol, while the thermodynamic parameters DeltaH and DeltaS were estimated to be -5.82 kJ/mol and 0.07 kJ/(molK), respectively.     

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.     

Activated carbon/iron oxide composites for the removal of atrazine from aqueous medium

The adsorption features of activated carbon and the oxidation properties of iron oxides were combined in a composite to produce new materials for atrazine removal from aqueous medium. Activated carbon/iron oxide composites were prepared at 1/1 and 5/1 mass ratios and characterized with powder X-ray diffractometry (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nitrogen adsorption measurements. The adsorption and oxidation processes were evaluated in batch experiments, in order to monitor the atrazine removal capacity of these composites. The main iron oxide actually present in the composites was goethite (alpha-FeOOH). Impregnation with iron oxide reduced the surface area by its deposition in the activated carbon pores. However, a higher iron concentration promoted a higher oxidation rate, indicating that the efficiency of the oxidation reaction is related with the iron content and not with the pre-concentration of the contaminant on the carbon surface through adsorption process.     

Adsorption isotherm and kinetic modeling of 2,4-D pesticide on activated carbon derived from date stones

In this work, the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) on activated carbon derived from date stones (DSAC) was studied with respect to pH and initial 2,4-D concentration. The experimental data were analyzed by the Freundlich isotherm, the Langmuir isotherm, and the Temkin isotherm. Equilibrium data fitted well with the Langmuir model with maximum adsorption capacity of 238.10 mg/g. Pseudo-first and pseudo-second-order kinetics models were tested with the experimental data, and pseudo-first-order kinetics was the best for the adsorption of 2,4-D by DSAC with coefficients of correlation R(2)>or=0.986 for all initial 2,4-D concentrations studied. The results indicated that the DSAC is very effective for the adsorption of 2,4-D from aqueous solutions.     

Diclofenac removal from water with ozone and activated carbon

Diclofenac (DCF) has been treated in water with ozone in the presence of various activated carbons. Activated carbon-free ozonation or single ozonation leads to a complete degradation of DCF in less than 15 min while in the presence of activated carbons higher degradation rates of TOC and DCF are noticeably achieved. Among the activated carbons used, P110 Hydraffin was found the most suitable for the catalytic ozonation of DCF. The influence of pH was also investigated. In the case of the single ozonation the increasing pH slightly increases the TOC removal rate. This effect, however, was not so clear in the presence of activated carbons where the influence of the adsorption process must be considered. Ecotoxicity experiments were performed, pointing out that single ozonation reduces the toxicity of the contaminated water but catalytic ozonation improved those results. As far as kinetics is concerned, DCF is removed with ozone in a fast kinetic regime and activated carbon merely acts as a simple adsorbent. However, for TOC removal the ozonation kinetic regime becomes slow. In the absence of the adsorbent, the apparent rate constant of the mineralization process was determined at different pH values. On the other hand, determination of the rate constant of the catalytic reaction over the activated carbon was not possible due to the effect of mass transfer resistances that controlled the process rate at the conditions investigated.     

Trivalent chromium removal from wastewater using low cost activated carbon derived from agricultural waste material and activated carbon fabric cloth

An efficient adsorption process is developed for the decontamination of trivalent chromium from tannery effluents. A low cost activated carbon (ATFAC) was prepared from coconut shell fibers (an agricultural waste), characterized and utilized for Cr(III) removal from water/wastewater. A commercially available activated carbon fabric cloth (ACF) was also studied for comparative evaluation. All the equilibrium and kinetic studies were conducted at different temperatures, particle size, pHs, and adsorbent doses in batch mode. The Langmuir and Freundlich isotherm models were applied. The Langmuir model best fit the equilibrium isotherm data. The maximum adsorption capacities of ATFAC and ACF at 25 degrees C are 12.2 and 39.56 mg/g, respectively. Cr(III) adsorption increased with an increase in temperature (10 degrees C: ATFAC--10.97 mg/g, ACF--36.05 mg/g; 40 degrees C: ATFAC--16.10 mg/g, ACF--40.29 mg/g). The kinetic studies were conducted to delineate the effect of temperature, initial adsorbate concentration, particle size of the adsorbent, and solid to liquid ratio. The adsorption of Cr(III) follows the pseudo-second-order rate kinetics. From kinetic studies various rate and thermodynamic parameters such as effective diffusion coefficient, activation energy and entropy of activation were evaluated. The sorption capacity of activated carbon (ATFAC) and activated carbon fabric cloth is comparable to many other adsorbents/carbons/biosorbents utilized for the removal of trivalent chromium from water/wastewater.     

Recycling of agricultural solid waste, coir pith: removal of anions, heavy metals, organics and dyes from water by adsorption onto ZnCl2 activated coir pith carbon

The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl(2) activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl(2) activated coir pith carbon is effective for the removal of toxic pollutants from water.     

Effect of compost age and composition on the atrazine removal from solution

Compost samples from two composting facilities, the Urbana (Illinois) Landscape Recycling Center (ULRC) and Illinois State University (ISU), were selected to examine the effect of compost age on atrazine removal from solution. The ULRC samples were made from yard waste without an additional nitrogen source. The ISU samples were made from yard waste or sawdust with the addition of manure. The 6-month-old ULRC compost had the greater capacity to remove atrazine from solution, which we attributed to its greater organic carbon content. The addition of nitrate into ULRC compost could influence the extent of atrazine removal, but did not have a significant impact on atrazine removal when applied to ISU compost, probably because manure was added to the yard waste to produce the compost. For both ULRC and ISU samples, the presence of sodium azide inhibited atrazine removal, suggesting that microbial activity contributed to the atrazine removal. Metabolic analysis demonstrated that hydroxyatrazine was the major identified metabolite that accumulated in solution before significant ring mineralization could occur. When compared with the ISU compost, the ULRC compost sample had a greater capacity to remove atrazine from solution during the 120 days of study because of the larger humic acid content. The experimental results suggested that less-mature compost may be better suited for environmental applications such as removing atrazine from tile-drainage waters.     

Hydrophobic carbon nanotubes for removal of oils and organics from water

In this work, we synthesized p-phenylenediamine modified carbon nanotubes (P-CNTs) by diazotization reaction. The resulting material shows a BET surface area of 285 m² g^?1 and a total volume of 0.65 cm³ g^?1 with abundant mesopores. Also, the P-CNTs exhibit good surface hydrophobicity with water contact angle of 140.8°, which should be attributed to the cooperation of both surface roughness and hydrophobic chemical compositions (aromatic rings linkages) of P-CNTs. Taking advantages of the intrinsic porosity and surface hydrophobicity, the resulting P-CNTs exhibit a notably selective absorbing ability and good recyclability for removal of organics and oils from water, which makes them the promising candidates for liquid–liquid separation and waste oil treatment.     

Arsenic removal from real-life groundwater by adsorption on laterite soil

The adsorption characteristics of arsenic on laterite soil, a low-cost natural adsorbent, were studied in the laboratory scale using real-life sample. The studies were conducted by both batch and continuous mode. Laterite soil was found to be an efficient adsorbent for arsenic removal from the groundwater collected from arsenic affected area. The initial concentration of arsenic in the sample was 0.33 ppm. Under optimized conditions the laterite soil could remove up to 98% of total arsenic. The optimum adsorbent dose was 20 g/l and the equilibrium time was 30 min. Isotherm studies showed that the process is favorable and spontaneous. The kinetics showed that the removal of arsenic by laterite soil is a pseudo-second-order reaction. In the column study the flow rate was maintained at 1.49 m3/(m2 h). Using 10 cm column depth, the breakthrough and exhaust time found were 6.75 h and 19.0 h, respectively. Height of adsorption zone was 9.85 cm, the rate at which the adsorption zone was moving through the bed was 0.80 cm/h, and the percentage of the total column saturated at breakthrough was 47.12%. The value of adsorption rate coefficient (K) and the adsorption capacity coefficient (N) were 1.21 l/(mgh) and 69.22 mg/l, respectively. Aqueous NaOH (1 M) could regenerate the adsorbent, and the regenerated adsorbent showed higher efficiency.     

Adsorption of aromatic organic acids onto high area activated carbon cloth in relation to wastewater purification

Adsorption of aromatic organic acids: benzoic acid (BA), salicylic acid (SA), p-aminobenzoic acid (pABA) and nicotinic acid (NA), onto high area activated carbon cloth from solutions in 0.4 M H(2)SO(4), in water at natural pH, in 0.1 M NaOH and also from solutions having pH 7.0 were studied by in situ UV-spectroscopic technique. The first-order rate law was found to be applicable for the kinetic data of adsorption. The rates and extents of adsorption of the organic acids were the highest from water or 0.4 M H(2)SO(4) solutions and the lowest from 0.1 M NaOH solution. The order of rates and extents of adsorption of the four organic acids in each of the four solutions (0.4 M H(2)SO(4), water, solution of pH 7.0 and 0.1 M NaOH) was determined as SA>BA>NA approximately pABA. These observed orders were explained in terms of electrostatic, dispersion and hydrogen bonding interactions between the surface and the adsorbate species, taking the charge of the carbon surface and the adsorbate in each solution into account. Adsorption of BA in molecular form or in benzoate form was analyzed by treating the solution as a mixture of two components and applying Lambert-Beer law to two-component system. The adsorption isotherm data of the systems studied were derived at 30 degrees C and fitted to Langmuir and Freundlich equations.     

NiOx modified cellulose cloth for the removal of U(VI) from water

In this present work, NiO_x nanoparticles were coated over cotton cloth for U⁶⁺ removal under various environmentally relevant conditions. Characterization of the NiO_x-coated cotton cloth showed a nanoflower-structured morphology over the cotton fabric, with poly-crystalline α-3Ni(OH)₂·2H₂O and microcrystalline cellulose on the surface. XRF analysis of the cloth revealed the presence of 93% of Ni, while XPS analysis indicated that the Ni present on the cloth was in the form of Ni²⁺2p_3/2 and Ni²⁺2p_1/2. The NiO_x-coated cotton cloth exhibited excellent U⁶⁺ immobilization with 93.5% removal within 6 min. The sorption capacity was ascertained to be 12.05 mg/g, and equilibrium studies indicated favorable monolayer adsorption. Solution pH had a significant effect on U⁶⁺ sorption on NiO_x-coated cotton cloth, with maximum immobilization occurring at pH 6. Sorption kinetics was best explained using pseudo-second order kinetics indicating chemisorption-based process. Post-sorption XPS of U⁶⁺sorbed NiO_x modified cotton cloth revealed only U⁶⁺ with no reduced forms, suggesting a pure adsorption-based immobilization mechanism. The superior performance even amongst the competing ions^-demonstrated that the NiO_x-coated cotton cloth is a low-cost, effective material for U⁶⁺ removal.     

Dye removal from wastewater using activated carbon developed from sawdust: adsorption equilibrium and kinetics

Mahogany sawdust was used to develop an effective carbon adsorbent. This adsorbent was employed for the removal of direct dyes from spent textile dyeing wastewater. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Langmuir model. The rates of adsorption were found to conform to the pseudo-second-order kinetics with good correlation. The equilibrium adsorption capacity of the sawdust carbon was determined with the Langmuir equation as well as the pseudo-second-order rate equation and found to be >300 mg dye per gram of the adsorbent. The most ideal pH for adsorption of direct dyes onto sawdust carbon was found to be 3 and below. The results indicate that the Mahogany sawdust carbon could be employed as a low cost alternative to commercial activated carbon in the removal of dyes from wastewater.     

Studies on the removal of arsenic (III) from water by a novel hybrid material

The present work provides a method for removal of the arsenic (III) from water. An ion-exchanger hybrid material zirconium (IV) oxide-ethanolamine (ZrO-EA) is synthesized and characterized which is subsequently used for the removal of selective arsenic (III) from water containing 10,50,100 mg/L of arsenic (III) solution. The probable practical application for arsenic removal from water by this material has also been studied. The various parameters affecting the removal process like initial concentration of As (III), adsorbent dose, contact time, temperature, ionic strength, and pH are investigated. From the data of results, it is indicated that, the adsorbent dose of 0.7 mg/L, contact time 50 min after which the adsorption process comes to equilibrium, temperature (25 ± 2), solution pH (5-7), which are the optimum conditions for adsorption. The typical adsorption isotherms are calculated to know the suitability of the process. The column studies showed 98% recovery of arsenic from water especially at low concentration of arsenic in water samples.     

The effect of acid treatment of carbon cloth on the adsorption of nitrite and nitrate ions

The effects of functional groups on the adsorption efficiency of nitrate and nitrite from water by carbon cloth were investigated. The carbon cloth was treated by sulfuric acid and used for the adsorption of nitrate and nitrite from water samples at nearly neutral solutions. The concentrations of ions in the solution were monitored using in situ UV spectroscopy. Acid treatment caused a significant increase in the adsorption rate of ions and the adsorption capacity of the adsorbent.