米糠对水中特定有机物的去除效率：动力学和热力学研究
Efficiency of rice bran for the removal of selected organics from water: kinetic and thermodynamic investigations.
作者信息
Akhtar Mubeena, Bhanger M I, Iqbal Shahid, Hasany S Moosa
机构信息
National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Pakistan.
出版信息
J Agric Food Chem. 2005 Nov 2;53(22):8655-62. doi: 10.1021/jf058060h.
The sorption efficiency of indigenous rice (Oryza sativa) bran for the removal of organics, that is, benzene, toluene, ethylbenzene, and cumene (BTEC), from aqueous solutions has been studied. The sorption of BTEC by rice bran is observed over a wide pH range of 1-10, indicating its high applicability to remove these organics from various industrial effluents. Rice bran effectively adsorbs BTEC of 10 microg mL(-1) sorbate concentration from water at temperatures of 283-323 +/- 2 K. The effect of pH, agitation time between solid and liquid phases, sorbent dose, its particle size, and temperature on the sorption of BTEC onto rice bran has been studied. The pore area and average pore diameter of rice bran by BET method are found to be 19 +/- 0.7 m(2) g(-1) and 52.8 +/- 1.3 nm. The rice bran exhibits appreciable sorption of the order of 85 +/- 3.5, 91 +/- 1.8, 94 +/- 1.4, and 96 +/- 1.2% for 10 microg mL(-1) concentration of benzene, toluene, ethylbenzene, and cumene, respectively, in 60 min of agitation time using 0.1 g of rice bran at pH 6 and 303 K. The sorption data follow Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) models. Sorption capacities have been computed for BTEC by Freundlich (32 +/- 3, 61 +/- 14, 123 +/- 28, and 142 +/- 37 m mol g(-1)), Langmuir (6.6 +/- 0.1, 7.5 +/- 0.13, 9.5 +/- 0.22, and 9.4 +/- 0.18 m mol g(-1)), and D-R isotherms (11 +/- 0.5, 16 +/- 1.3, 30 +/- 2.2, and 33 +/- 2.5 m mol g(-1)), respectively. The Lagergren equation is employed for the kinetics of the sorption of BTEC onto rice bran and first-order rate constants (0.03 +/- 0.002, 0.04 +/- 0.003, 0.04 +/- 0.003, and 0.05 +/- 0.004 min(-1)) have been computed for BTEC at their concentration of 100 mug mL(-1) at 303 K. Studies on the variation of sorption with temperatures (283-323 K) at 100 mug mL(-1) sorbate concentration gave thermodynamic constants DeltaH (kJ mol(-1)), DeltaG (kJ mol(-1)), and DeltaS (J mol(-1) K(-1)). The results indicate that the sorption of organics onto rice bran is exothermic and spontaneous in nature under the optimized experimental conditions selected. This sorbent has been used successfully to accumulate and then to determine benzene, toluene, and ethylbenzene in wastewater sample.
研究了本地米糠对水溶液中有机物，即苯、甲苯、乙苯和异丙苯（BTEC）的吸附效率。在1 - 10的宽pH范围内观察到米糠对BTEC的吸附，这表明其在从各种工业废水中去除这些有机物方面具有很高的适用性。米糠在283 - 323±2 K的温度下能有效吸附水中浓度为10μg mL(-1)的BTEC。研究了pH、固液相搅拌时间、吸附剂剂量、其粒径和温度对BTEC在米糠上吸附的影响。通过BET法测得米糠的孔面积和平均孔径分别为19±0.7 m(2) g(-1)和52.8±1.3 nm。在pH为6、温度为303 K、使用0.1 g米糠搅拌60 min的条件下，米糠对浓度为10μg mL(-1)的苯、甲苯、乙苯和异丙苯的吸附量分别达到85±3.5%、91±1.8%、94±1.4%和96±1.2%。吸附数据符合Freundlich、Langmuir和Dubinin - Radushkevich（D - R）模型。通过Freundlich（32±3、61±14、123±28和142±37 m mol g(-1)）、Langmuir（6.6±0.1、7.5±0.13、9.5±0.22和9.4±0.18 m mol g(-1)）以及D - R等温线（11±0.5、16±1.3、30±2.2和33±2.5 m mol g(-1)）分别计算了BTEC的吸附容量。采用Lagergren方程研究BTEC在米糠上吸附的动力学，在303 K下，对于浓度为100μg mL(-1)的BTEC计算出一级速率常数（0.03±0.002、0.04±0.003、0.04±0.003和0.05±0.004 min(-1)）。在吸附质浓度为100μg mL(-1)时，研究了温度（283 - 323 K）变化对吸附的影响，得到了热力学常数ΔH（kJ mol(-1)）、ΔG（kJ mol(-1)）和ΔS（J mol(-1) K(-1)）。结果表明，在所选的优化实验条件下，有机物在米糠上的吸附是放热且自发的。这种吸附剂已成功用于富集并测定废水样品中的苯、甲苯和乙苯。
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