摘要:
研究区两类主要农业土壤在实验温度和吸附平衡液浓度相同时,酸性淋溶土(红壤、黄红壤)SO42-吸附量均高于近中性水成土 (水稻土、潮土),与土壤游离Fe,Al含最呈显著正相关,吸附过程均符合Freundlich和Ternkin方程描述规律:低温(10℃)时吸附量均高于常温 (25℃),表明吸附系放热反应,有利于冬,春酸雨频仍季节土壤对SO42-的固定,研究表明土壤吸附过程由快速反应(0—4h)和慢速反应(4—48h)两部份组成,且符合反映吸附机制较复杂的多级动力学反应规律,0.01mol/l Ca(NO3)2和1.0mol/l NaCl对土壤吸附态SO42-的解吸率较高,表明SO42-主要被土壤吸附于带正电荷的氧化物胶体表面,离子交换可逆吸附机制似占较大优势。
Abstract:
At experimental temperature (10℃ or 25℃ ) and concentration of SO42- in sorption-equilibrated solution,the amounts of SO42- adsorbed by acidic soil group (red soil, yellow-red soil)was larger than that adsorbed by nearly neutral soil group (paddy soil, hydro-flu vent soil), it was found to be well correlated with the content of active free Fe, Al oxide in the above soils. It was shown that the sorption data could fit both the Freundlich and Temkin isotherm equations closely.The adsorption process of sulfate was demonstrated as an exothermic reaction and could be described by the mul tiple-order kinetic equation.It was found that the desorption rates of adsorbed SO42- by 0.01mol/1 Ca(NO3)2 and 1.0mol/l NaCl were very high, it would be extrapolated that sulfate anion as a counterion was sorbed on the colloid surface which brought positive charge,i.e. Fe(Al) oxide. The adsorption mechanism seemed to be a reversible ion exchange reaction,thus the adsorbed SO42-could be mostly desor-bed by the neutral salt.
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