聚合铁钛混凝剂对印染废水的处理

Treating dyeing wastewater with a kind of polyferric titanium sulfate

采用钛铁矿为主要原料,以硫酸溶出部分铁和钛,并调节Ti/Fe比、碱化度制备高效的新型含钛聚合硫酸铁混凝剂(T-PSF),将其用于分散兰和活性黄2种模拟印染废水的脱色处理并研究其混凝去除机理。实验结果表明,在Ti/Fe为1∶6和碱化度为2.0时,制备出的T-PSF混凝效果最好。T-PSF对分散兰的去除率为94.3%,比FeCl_3的去除率提高53.8%;对活性黄的去除率为34.0%,比FeCl_3提高12.7%。T-PSF处理分散兰和活性黄的最佳投加量均为0.3 mmol·L^(-1),最佳水样初始pH分别为6和8。絮体粒径及结构分析结果表明,T-PSF处理分散兰过程中形成的絮体粒径较FeCl_3大,处理活性黄过程中所形成的絮体粒径较FeCl_3小,但絮体结构均比FeCl_3更密实。结合T-PSF的表征、Zeta电位及絮体特性分析表明,在分散染料去除过程中,T-PSF产生的多羟基钛铁聚合物的电中和及吸附架桥起主要作用;对于活性染料的去除,主要机制为T-PSF水解产生的带正电的多羟基钛铁聚合物的吸附络合作用。

In this study,a new polyferric-titanium sulfate coagulant(T-PSF)was prepared through dissolving a part of iron and titanium from ilmenite with sulfuric acid and adjusting Ti/Fe ratio and basicity.The T-PSF was used to treat two kinds of simulated dye wastewater(disperse blue and reactive yellow),and its coagulation mechanisms were also discussed.The results showed that T-PSF had a good coagulation performance with the Ti/Fe ratio of 1∶6 and basicity of 2.0.The removal efficiencies of disperse blue and reactive yellow by T-PSF coagulation were 94.3%and 34.0%,which were 53.8%and 12.7%higher than those by FeCl3 coagulation,respectively.For disperse blue and reactive yellow removal,the optimal T-PSF dosages were 0.3 mmol·L-1 and the optimum pHs were 6 and 8,respectively.In compared with flocs during FeCl3 coagulating dyes,larger and more compact ones occurred during T-PSF coagulating disperse blue,while smaller and more compact one occurred during T-PSF coagulating reactive yellow.In combination with T-PSF characterization,Zeta potential and other properties of flocs,charge neutralization and bridging of polyhydroxy-ferrotitanium polymers through T-PSF hydrolysis were identified as playing a key role in disperse dyes removal,while the adsorption and complexation of positively charged polyhydroxy-ferrotitanium polymers through T-PSF hydrolysis were identified as playing a key role in reactive dyes removal.