双氰胺甲醛型改性脱色絮凝剂的合成、表征及脱色性能

为提高双氰胺甲醛型脱色絮凝剂的脱色性能,以尿素、三聚氰胺为交联剂,以双氰胺、甲醛为原料制备了改性脱色絮凝剂,并用其处理模拟染料废水.研究了不同染料的初始浓度、p H值、投加量、无机盐以及与聚合氯化铝(PAC)复配使用等条件对脱色率的影响.实验结果证明改性的脱色剂具有较好的脱色性能.相同投加量条件下,未改性脱色剂的最大脱色率为89.7%,而改性脱色剂的脱色率能达到94.6%.红外光谱图表明染料分子和脱色剂发生了相互作用.单因素试验研究表明单独使用改性脱色剂时,最佳投加量为120 mg·L~(-1),单独使用PAC时,最佳投加量为60 mg·L~(-1).正交试验法确定了最优适用条件为:改性脱色剂加入量70 mg·L~(-1),聚铝加入量为50 mg·L~(-1),改性脱色剂和PAC的复配使污水处理成本下降约20%.脱色剂的改性和改性脱色剂与PAC的复配显著提高了脱色剂的耐盐性.

Preparation, characterization and flocculating performance of the modified dicyandiamide and formaldehyde decolorization flocculant

To improve the decolorization performance, a modified flocculant was synthesized by using dicyandiamide and formaldehyde as materials and urea and melamine as the crosslinking agent. The modified decolorization flocculant was used in the simulated textile wastewater treatment experiment. The effect of concentration of different dyes, pH, dosage of flocculant, inorganic salt, and the addition of polymeric aluminium chloride (PAC) on the flocculation ability were systematically investigated. The results show that the modified decolorization flocculant exhibited excellent performance on the treatment of simulated textile wastewater. With the same dosage, the decolorization efficiency of the modified flocculant could reach 94.6%, which was higher than 89.7% of efficiency of the unmodified flocculant. Infrared spectrum also shows that there was an interaction between the modified decolorization flocculant and the dye. Results of The single factor experiments indicate that the optimum dosage of the modified decolorization flocculant and PAC was 120 mg·L^-1 and 60 mg·L^-1 respectively, when they were used alone. However, when the modified decolorization flocculant was combined with the PAC, the optimum conditions were obtained by the orthogonal experiment method, with under 70 mg·L^-1of the modified decolorization flocculant and 50 mg·L^-1 of the PAC. These modification and combination significantly increased the salt tolerance of the decolorization flocculant and decreased the wastewater treatment cost by 20%.