微波活化-水解-接枝制煤矸石淀粉基絮凝剂

摘要

Composite flocculants were prepared by an activating-hydrolysis-graft method with microwave as the only heat source, and coal gangue and starch were used as the raw materials. The results show that the turbidity decreasing and COD removal rates of the prepared flocculants (gangue based PAFC-corn (or potato) starch) are higher than commercial PAM in the treatment of water from Shuicheng River or coal-washing wastewater, while the cost is less than 1/6 of the commercial PAM. 70 mesh GAC and 200 mesh gangue powder were mixed with a mass ratio of 2:1 and activated with 800 W microwave power for 30 min, and the relative Al/Fe leaching rate is 1.62. The GAC after two treatment cycles has a methylene blue adsorption value of 40.77 mg⋅g-1 higher than that of new carbon, and the relative Al/Fe leaching rate is 2.017. After hydrolyzing in 320 W microwave power for 18 min, the basicity of the gangue based PAFC is 68.9%and meets GB 15892-2003. The grafting rate is 71% after mixing the gangue-based PAFC and corn starch (1:0.06) for 16 min in 400 W microwave power, which is close to the limiting grafting rate of 74%. The failure temperature points always exist in E-Wan furnace for the grafting, which are 96.8℃, 98.6℃ and 97.8℃ for corn, potato and cassava starch, respectively. The grafting rate is 79%of that of the microwave grafting.%以煤矸石与淀粉为原料，以微波为唯一热源，经过活化、水解、接枝，制备了三种新型的煤矸石基PAFC-淀粉复合絮凝剂。自制煤矸石基PAFC-玉米(马铃薯)淀粉絮凝剂对水城河水、洗煤废水的浊度去除率与COD去除率均高于市售PAM，且成本不高于市售PAM的1/6。实验结果表明：将70目活性炭与150.0 g 200目煤矸粉以2.0：1的质量配比充分混合后在800 W功率下活化30 min，铝铁相对浸出率可达1.62；活性炭经2次循环后亚甲蓝吸附值比新炭提高40.77 mg⋅g-1，铝铁相对浸出率也同时达到峰值2.107，表明该过程为协同活化；将浸出液在320 W微波场中水解18 min，所制煤矸石基PAFC的盐基度为68.9%，达到GB 15892-2003标准；在1：0.06的最佳质量配比下，固体煤矸石基PAFC与玉米淀粉在400W微波场中接枝16 min时的接枝率为71%，接近极限接枝率74%。玉米淀粉、马铃薯淀粉与木薯淀粉在电子万用炉上与煤矸石基PAFC接枝均存在与功率无关的“失效温度点”，分别为96.8、98.6、97.8℃，且接枝速度仅为微波接枝速度的79%。