Authors: Kang Sup Chung, Mi Ae Kim, Hwan Lee, Yong Jae Suh, Dae Sup Kil, B.C. Dave, Jae Chun Lee
Abstract: Ion-sieve type manganese oxide spinels for the selective adsorption of lithium(Li) from
seawater were prepared and their properties were examined. LiM0.5Mn1.5O4 (M=Mg, Zn) precursors,
in which part of manganese(Mn) was substituted with magnesium(Mg) or zinc(Zn), were synthesized
through the solid-state reaction. The adsorbents, HM0.5Mn1.5O4 (M=Mg, Zn) were derived from
LiM0.5Mn1.5O4 (M=Mg, Zn) by acid treatment. The optimum acid treatment was obtained at
hydrochloric acid concentration of 0.5M and 0.3M for LiMg0.5Mn1.5O4 and LiZn0.5Mn1.5O4
precursors, respectively. Both cases required thrice-conducted acid treatments for the best results.
The adsorption of Li by HMg0.5Mn1.5O4 and HZn0.5Mn1.5O4 adsorbents followed the Freundlich
equation and the maximum adsorption of Li in artificial seawater was 30.3 mg/g and 33.1 mg/g,
respectively. The adsorption efficiency of Li by HMg0.5Mn1.5O4 and HZn0.5Mn1.5O4 adsorbents in
artificial seawater, in which Li concentration was adjusted to 0.2 mg/L, was as high as 88% and 89%.
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Authors: Zhang Weng, Z.Q. Jing, Yu Kong, Wei Shen
Abstract: This study investigated the adsorption of congo red by activated carbon-attapulgite composite adsorbent (ACA) and zeolite-attapulgite composite adsorbent (ZA) from aqueous solution. All of these two adsorbents have mesopores and macropores structure different from general activated carbon adsorbent with micropores distribution through analysis of mercury porosimeter .The research focused on the effects of adsorption capacity in four aspects: contact time, solution pH, temperature and initial dye concentration. The results indicated that ACA had higher adsorption rate in the first 30 min contact time and ZA had higher removal percentage because of the difference on the pore size and total pore area. There was little difference on removal percentage of ACA and ZA when pH changing from 1 to 13 and the adsorption rate exceeded 94% in all kinds of pH condition. The removal efficiency of congo red on ACA and ZA increased from 92% to 95% with increase of temperature from 293K to323K. The reduction rate of congo red decreased with an increase in the initial congo red concentration for ACA and ZA.These results suggest that all of the two adsorbents is a potential low-cost adsorbent for the dye removal from industrial wastewater.
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Authors: Hong Qin Xue, Zhao Qian Jing, Zheng Wang
Abstract: The adsorption technique using fly ash composite material has been applied for the removal
of Cr(VI) from aqueous samples. Batch experiments have been carried out for the adsorption of Cr(VI)
onto fly ash composite material. The effects of various process parameters, namely, pH, adsorbent
dosage, initial Cr(VI) concentration and contact time has been studied in batch systems. Maximum
metal removal ratio was observed at pH 5.0~5.5, and the sorption reaction was an endothermic process.
The results revealed that the hexavalent chromium is considerably adsorbed on this adsorbent and it
could be an economical method for the removal of hexavalent chromium from aqueous systems.
143
Authors: Zai Fu Yang, Xiao Jing Yang, Li Hong Sun, Lian Lian Xu
Abstract: ABSTRACT: Cation adsorbent was prepared from the Solidago Canadensis（which are abandoned agricultural land of alien invasive plants）by Sulfuric acid esterification modified , isoamyl alcohol as reaction medium. Design L934 orthogonal experiment, the Solidago canadensis cation exchange adsorbent, the optimal preparation conditions. Experimental results show that at 15°C, concentrated sulfuric acid and amyl alcohol volume ratio of 5:6 obtained under conditions of Solidago canadensis cation exchange adsorbent for Pb(II) exchange best. The experimental results of Pb(II) adsorption onto the Solidago Canadensis based cation adsorbent showed that the best conditions are: the initial pH 5, the concentration of Pb(II) 300mg/L，the dosage of cation adsorbent 1.2mg/L and adsorption time 3h. The adsorption data were analyzed by using pseudo-first-order and pseudo-second-order kinetic models were found to follow the pseudo-second-order kinetic model.
75
Authors: Yu Wang, Xiao Qing Dong, Bao Hua Zhou, Zhi Bing Xu
Abstract: The defluoridation capacity of phosphate rock in the presence of oxalic acid was investigated using batch experiments. Defluoridation capacity of phosphate rock was enhanced in the presence of oxalic acid, removing fluoride from 22.46% up to 57.98% with 2.5 mmol/L oxalic acid. The contact time and pH for maximum fluoride uptake were found 2 h and 5, respectively. Maximum adsorption capacity (0.36 mg/g) of fluoride on phosphate rock was observed at 50 mg/L initial fluoride concentration using 2 g adsorbent dose.
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