质子化壳聚糖的除磷性能

Dephosphorization effect of protonated chitosan

壳聚糖是一类无毒无害的天然高分子絮凝剂,为了提高壳聚糖在污水处理中的除磷性能,采用硫酸溶液对壳聚糖进行质子化改性;考察了质子化度(硫酸溶液pH值)、吸附时间以及原水pH值对除磷效率的影响。研究结果表明,质子化度越大,总磷去除效率越高;在吸附时间为40～50 min的范围内,总磷去除率最大;原水pH值对质子化壳聚糖的总磷去除效率有明显影响,在质子化度较低时(硫酸溶液pH值≥3),随着原水pH值的增加,总磷去除率降低,在质子化度较高时(硫酸溶液pH值=2),在原水pH=6时,总磷去除率最大;质子化壳聚糖的吸附过程较好地遵循Lagergren准二级动力学模型和Langmuir吸附等温方程,吸附热力学参数ΔH<0,ΔG<0,ΔS<0,吸附过程表现为放热、自发的单分子层化学吸附过程。

Chitosan is a natural macromolecule innoxious flocculant. Chitosan was protonated by sulfuric acid solution to enhance dephosphorization effect in wastewater treatment. The effect of protonation degree （pH value in sulfuric acid solution） , adsorption time and pH value in raw water on dephosphorizing efficiency was researched. The results showed that bigger protonation degree can result in higher total phosphate removal rate （TPRR） ; TPRR was highest at 40 -50 rain of adsorption time; pH value in raw water had obviously effect on TPRR of protonated ehitosan. TPRR decreased with pH value of raw water increasing when protonation degree was lower （pH ≥3 in sulfuric acid solution） ; TPRR was highest at pH = 6 in raw water when protonation degree was bigger （pH = 2 in sulfu- ric acid solution）. The absorption process of protonated chitosan better fitted to pseudo - second order Lagergren equation and Langmuir absorption equation. Thermodynamics parameters of adsorption were △H 〈 0, △G 〈 0, and △S 〈 0, adsorption behavior was exothermic, spontaneous and single molecular layer chemical adsorption process.