聚天冬氨酸/木质纤维素水凝胶的制备及吸附性能

采用水溶液聚合法合成聚天冬氨酸(PASP)/木质纤维素(LNC)水凝胶;考察了预处理时间、预处理温度、KMnO4浓度、戊二醛用量、PASP的用量、反应时间以及反应温度对PASP/LNC水凝胶吸附Pb~(2+)、Cd~(2+)性能的影响;运用Langmuir吸附等温线计算PASP/LNC水凝胶最大吸附量;使用HNO3对PASP/LNC水凝胶进行脱附再生实验;采用SEM和FTIR对水凝胶的结构进行表征。吸附结果表明:预处理时间15min,预处理温度50℃、KMnO4浓度0.06mol·L~(-1)、戊二醛用量1.00g、PASP用量11g、反应时间3.5h且反应温度70℃时,对Pb~(2+)、Cd~(2+)的平衡吸附容量分别为980.39mg·g~(-1)、813.01mg·g~(-1)。吸附/脱附循环实验表明:循环吸附脱附4次后PASP/LNC水凝胶吸附量仍较高,PASP/LNC水凝胶是一种可循环利用的吸附剂。表征结果表明:PASP/LNC水凝胶的表面有大小不等的孔隙,PASP的—COOH与LNC的O—H发生缩聚反应,形成具有三维网络结构的水凝胶。

Preparation and absorption properties of polyaspartic acid/lignocellulose hydrogels

Polyaspartic acid(PASP)/lignocellulose (LNC) hydrogels were synthesized through aqueous polymerization method; the effects of pretreatment time, pretreatment temperature, KMnO₄ concentration, glutaraldehyde amount, PASP amount, reaction time and reaction temperature on adsorption property of PASP/LNC hydrogels for Pb²⁺, Cd²⁺ were evaluated; the maximum adsorption capacity of PASP/LNC hydrogels was calculated by Langmuir adsorption isotherm; HNO₃ was used to perform desorption and regeneration experiments of PASP/LNC hydrogels; the structure of the hydrogels was characterized by SEM and FTIR. The adsorption result shows that when the pretreatment time is 15 min, the pretreatment temperature is 50 ℃, the KMnO₄ concentration is 0.06 mol·L^-1, the glutaraldehyde amount is 1.00 g, the PASP amount is 11 g, the reaction time is 3.5 h and the reaction temperature is 70 ℃, the equilibrium adsorption capality for Pb²⁺, Cd²⁺ could reach 980.39 mg·g^-1, 813.01 mg·g^-1. The adsorption/desorption cycling experiment indicates that the adsorption capality of PASP/LNC hydrogels is ideal after four cycles of adsorption/desorption, so PASP/LNC hydrogels are confirmed as a adsorbent for recycling. The characterization results show that the surface of PASP/LNC hydrogels has gap of varying sizes, polycondensation reaction is developed between -COOH of PASP and O-H of LNC, which forms hydrogels of three-dimensional network structure.