不同铝源羟基氧化铝除氟性能及机理研究

Defluorination performance of Al OOH with different aluminum sources and mechanism thereof

采用共沉淀法,以Al2(SO4)3·18H2O和Al Cl3·6H2O为铝源,分别制备了2种用于除氟的羟基氧化铝吸附剂。通过吸附试验,从吸附速率、p H值影响、吸附等温线3方面评价吸附剂的吸附性能。借助红外光谱(FTIR)和能谱(EDX)2种手段,对吸附剂进行表征,进而探讨吸附机理。结果表明,以Al2(SO4)3·18H2O为铝源制备的吸附剂,在投加量为0.4 g/L,F-的质量浓度为8 mg/L,温度为25℃,溶液p H值为7时,吸附量为37 mg/g,具有良好的除氟效果,其吸附规律符合Langmuir等温方程,动力学符合准二级动力学方程,最大吸附量为138.60 mg/g,明显高于以Al Cl3·6H2O为铝源所制备的吸附剂的最大吸附量96.62 mg/g。Al2(SO4)3·18H2O制备的吸附剂中包含的SO42-能够与F-发生置换,且SO42-的存在稳定了反应过程中溶液p H值的变化,有利于氟的吸附。因此使用经济性更好的Al2(SO4)3·18H2O制备吸附剂,比Al Cl3·6H2O所制备的吸附剂具有更好的应用前景。

With Al2 （SO4）3-18H2O and AlCl3·6H2O as aluminum sources, two kinds of A1OOH were pre- pared by co-precipitation method and were used as adsorbents to remove F-. According to the test results, the adsorption performance of the said two adsorbents on F- were evaluated from aspects of adsorption rate, pH value influence and adsorption isotherm. The adsorbents were characterized by FFIR and EDX, and then, the adsorp- tion mechanism was discussed. The results showed that, under the condition that the adsorbent dosage was 0.4 g/ L, the mass concentration of F- was 8 mg/L, the temperature was 25℃. the solution pH value was 7, the adsor- bent prepared with Al2（SO4）3·18H2O as the aluminum source had a good defluorination effect with adsorbing ca- pacity of 37 mg/g. Besides, its adsorption pattern fit Langmuir isotherm equation, and the adsorption kinetics fit pseudo-second order kinetic equation, the maximal adsorbing capacity was 138.60mg/g, which was obviously superior to that of the adsorbent prepared with AlCl3·6H2O （96.62mg/g）. The SO42- in the adsorbent prepared with AlE（SO4）3·18H=O could be replaced by F-, and it stabilized the pH value of the solution during the reaction pro- cess, which was also beneficial to fluoride adsorption. Therefore, Compared to adsorbent prepared by AlCl3·6H2O, using adsorbent prepared by Al2（SO4）3·18H2O to remove fluoride was more economical, and its application prospect was also better.