改性凹凸棒土的优化定向制备及对腐殖酸的吸附效果

以天然凹凸棒土为原料,以去除以腐殖酸为代表的天然有机物为目的,研究酸活化、热处理和十八烷基三甲基氯化铵(OTAC)有机改性3种改性方法,进行定向筛选。进一步比较3种方法联合改性凹土后对腐殖酸的吸附效果,确定最优定向改性方法。结果表明,先酸处理后OTAC改性凹土对腐殖酸的吸附效果最好,改性凹土投药量为0.7 g/L时,腐殖酸的去除率可达97%。利用正交实验确定凹土改性的最佳工艺条件、钠化时间和有机改性剂的用量对改性凹土吸附腐殖酸的能力影响显著。改性的最佳工艺条件为:酸浓度3 mol/L,氯化钠浓度0.5 mol/L,钠化时间2 h,改性剂用量为凹土质量的3%,微波改性时间为9 min。单独投加改性凹土时pH值对腐殖酸的吸附效果有重要影响。该方法制备的改性凹土在水处理工艺有良好的应用前景。

Optimized preparation of directional modified attapulgite and its application to absorb humic acid

This study aimed to remove natural organic matter such as humic acid through the modification and use of raw attapulgite to study three modification methods including acid activation, heat treatment, and octadecyl trimethyl ammonium chloride (OTAC) organic modification. The best modification method was chosen by comparing the effects of three combined modifications on attapulgite. The results showed that the OTAC modification pretreated by acid had the best adsorbing effect on humic acid. The removal efficiency of humic acid could reach 97% when the dosage of modified attapulgite was 0.7 g/L. The length of sodium treatment and the dosage of organic modifier showed significant effects on modifying the attapulgite's ability to adsorb humic acid when using orthogonal experiment analysis to confirm optimum conditions of attapulgite modification. The optimum conditions of modification were as follows: 3 mol/L of the acid concentration, 0.5 mol/L of the sodium chloride concentration, 2 hours of the sodium treatment, 3% of the natural attapulgite's quantity as the quantity of the modifier, and 9 minutes of the microwave modified time. The pH value had a significant effect on adsorbing humic acid when adding modified attapulgite alone. Therefore, the method described above offers broad development and application potential in the water treatment process.