A low-cost adsorbent was prepared from sludge and straw by pyrolysis in a dried state with the surface area of the adsorbent of 829.49 m2·g?1,micropore volume of 0.176 cm2·g?1 and average pore radius of 5.0 ...A low-cost adsorbent was prepared from sludge and straw by pyrolysis in a dried state with the surface area of the adsorbent of 829.49 m2·g?1,micropore volume of 0.176 cm2·g?1 and average pore radius of 5.0 nm.The kinetic,equilibrium isotherm and thermodynamic characteristics of trisodium 1-(1-naphthylazo)-2-hydroxynaphthalene-4′,6,8-trisulphonate(acid scarlet 3R)onto the adsorbent from sludge and straw were investigated.The results indicated that the pseudo second order adsorption was the predominant adsorption mechanism of acid scarlet 3R.Thus,the adsorption phenomenon was suggested as a chemical process.The adsorption data were fitted better with Langmuir model than Freundlich model,indicating that the adsorption of acid scarlet 3R belonged to the monolayer adsorption and mainly occurred in micropores.展开更多
A low-cost adsorbent modified kaolin clay(MKC) was synthesized and utilized for Cr(VI) removal from aqueous solution. Adsorption experiments were carried out as a function of adsorbent dosage, solution pH, Cr(VI) mass...A low-cost adsorbent modified kaolin clay(MKC) was synthesized and utilized for Cr(VI) removal from aqueous solution. Adsorption experiments were carried out as a function of adsorbent dosage, solution pH, Cr(VI) mass concentration, contact time, electrolyte, and temperature. It is found that the adsorption efficiency is high within a wide pH range of 2.5-11.5, and equilibrium is achieved within 180 min. Increases in temperature and electrolyte concentration decrease the adsorption. The adsorption follows the pseudo-second-order kinetic model. The Langmuir isotherm shows better fit than Freundlich isotherm. The maximum uptake capacities calculated from the Langmuir model are 15.82, 15.55 and 15.22 mg/g at 298, 308 and 318 K, respectively. Thermodynamic parameters reveals the spontaneous and exothermic nature of the adsorption. The FTIR study indicates that hydroxyl groups, NH4+ ions and NO3- ions on MKC surface play a key role in Cr(VI) adsorption. The Cr(VI) desorbability of 86.53% is achieved at a Na2CO3 solution. The results show that MKC is suitable as a low-cost adsorbent for Cr(VI) removal which has higher adsorption capacity and faster adsorption rate at pH close to that where pollutants are usually found in the environment.展开更多
基金Supported by the Shanxi Science and Technology Agency Research Project(20100321085)the Scientific Research Foun-dation of the Shanxi Education Department(20111029)
文摘A low-cost adsorbent was prepared from sludge and straw by pyrolysis in a dried state with the surface area of the adsorbent of 829.49 m2·g?1,micropore volume of 0.176 cm2·g?1 and average pore radius of 5.0 nm.The kinetic,equilibrium isotherm and thermodynamic characteristics of trisodium 1-(1-naphthylazo)-2-hydroxynaphthalene-4′,6,8-trisulphonate(acid scarlet 3R)onto the adsorbent from sludge and straw were investigated.The results indicated that the pseudo second order adsorption was the predominant adsorption mechanism of acid scarlet 3R.Thus,the adsorption phenomenon was suggested as a chemical process.The adsorption data were fitted better with Langmuir model than Freundlich model,indicating that the adsorption of acid scarlet 3R belonged to the monolayer adsorption and mainly occurred in micropores.
基金Project(2012BAJ24B03)supported by the National Science and Technology Support Program of China
文摘A low-cost adsorbent modified kaolin clay(MKC) was synthesized and utilized for Cr(VI) removal from aqueous solution. Adsorption experiments were carried out as a function of adsorbent dosage, solution pH, Cr(VI) mass concentration, contact time, electrolyte, and temperature. It is found that the adsorption efficiency is high within a wide pH range of 2.5-11.5, and equilibrium is achieved within 180 min. Increases in temperature and electrolyte concentration decrease the adsorption. The adsorption follows the pseudo-second-order kinetic model. The Langmuir isotherm shows better fit than Freundlich isotherm. The maximum uptake capacities calculated from the Langmuir model are 15.82, 15.55 and 15.22 mg/g at 298, 308 and 318 K, respectively. Thermodynamic parameters reveals the spontaneous and exothermic nature of the adsorption. The FTIR study indicates that hydroxyl groups, NH4+ ions and NO3- ions on MKC surface play a key role in Cr(VI) adsorption. The Cr(VI) desorbability of 86.53% is achieved at a Na2CO3 solution. The results show that MKC is suitable as a low-cost adsorbent for Cr(VI) removal which has higher adsorption capacity and faster adsorption rate at pH close to that where pollutants are usually found in the environment.
