生物絮凝剂及磁絮凝技术在制革废水铬处理中的应用

发布时间：2018-03-26 19:07

  本文选题：高铬浓度废水　切入点：磁粉　出处：《陕西科技大学》2017年硕士论文

【摘要】：针对制革中存在的高铬铬鞣废液,本文以磁粉加速氢氧化铬胶体沉降的加碱磁絮凝技术进行处理,再通过酸法溶解氢氧化铬胶体,分离磁粉,并将溶解的氢氧化铬胶体制成铬粉,实现高铬浓度废液中的铬的循环使用。在加碱磁絮凝处理实验中,以铬的去除率和氢氧化铬沉降速率为指标,考察了碱用量、时间、温度、磁粉用量对含铬废水絮凝的影响,结果表明:按n(OH-):n(Cr~(3+))=4:1的摩尔比投加氢氧化钠后,常温水解30min,铬离子的水解基本完成,上层清液总铬含量在30mg/L以下,且当磁粉与铬(以Cr_2O_3计)质量比为1:1时,沉降效果最佳。对于絮凝后所得含磁氢氧化铬,本论文通过加浓硫酸溶解氢氧化铬后再过滤未溶解磁粉得到含铬溶液,去除铬溶液的水分即可得到自制铬粉。对自制铬粉工艺进行优化后所得铬粉,在氯化钠、硫酸钠、铬含量、碱度、有机物含量等指标上与工业铬粉有所差异。在鞣制时适当增加自制铬粉的用量,可使其鞣革收缩温度达到工业铬粉的效果,自制铬粉鞣革坯颜色较浅,皮身扁薄。针对中和、复鞣、染色、加脂等工序产生的废水含Cr~(3+)较低、及其成分复杂、难以处理的特点,利用已有的从秸秆中通过微生物发酵制得的生物絮凝剂对模拟含铬溶液中Cr~(3+)进行脱除。结果表明:当温度为30℃,pH为7.5,反应总时间为40min时,生物絮凝剂的脱铬效果较好,可实现模拟含铬溶液中Cr~(3+)浓度低于1.5mg/L的标准。但生物絮凝剂的脱铬性能受聚丙烯酸复鞣剂、加脂剂、染料等因素影响,故利用铬革屑吸附除杂,再用生物絮凝剂处理。对生物絮凝剂的结构及其脱铬原理分析如下:(1)生物絮凝剂比表面积较小,吸附能力有限;(2)红外光谱、紫外光谱、酸碱滴定法表明生物絮凝剂含有较多羧基,约为8mmol/g,使其在碱性水溶液中的溶解性较好,对阳离子性的铬配合物絮凝作用较强;(3)碱性条件下,生物絮凝剂分子链上的羧酸类基团电离度较大,亲水性较强,铬配合物的水解、配聚作用较强,从而产生吸附、架桥等絮凝作用,有利于铬的脱除。
[Abstract]:In view of the high chromium chrome tanning waste liquor in tannery, the magnetic powder was treated with alkali magnetic flocculation technology to accelerate the colloidal deposition of chromium hydroxide, and then the chromic hydroxide colloid was dissolved by acid method to separate the magnetic powder. Chromium powder was prepared from the colloidal chromium hydroxide solution to realize the recycling of chromium in the waste liquid with high chromium concentration. In the experiment of adding alkali magnetic flocculation, the removal rate of chromium and the settling rate of chromium hydroxide were used as indexes, and the amount of alkali, time and temperature were investigated. The effect of the amount of magnetic powder on the flocculation of chromium-containing wastewater was studied. The results showed that the hydrolysis of chromium ions was basically completed at room temperature after adding sodium hydroxide at the molar ratio of 4: 1 of n(OH-):n(Cr~(3, and the total chromium content of the supernatant was below 30mg/L. When the mass ratio of magnetic powder to chromium (calculated as Cr_2O_3) is 1:1, the settling effect is the best. For the magnetic chromium hydroxide after flocculation, the chromium-containing solution is obtained by adding concentrated sulfuric acid to dissolve chromium hydroxide and then filtering the insoluble magnetic powder. Self-made chromium powder can be obtained by removing water from chromium solution. After optimizing the process of self-made chromium powder, chromium powder can be obtained in sodium chloride, sodium sulfate, chromium content, alkalinity, etc. The content of organic matter is different from that of industrial chromium powder. The shrinkage temperature of tanning leather can reach the effect of industrial chromium powder when the dosage of self-made chrome powder is increased when tanning, the color of chrome powder tanned by self-made chrome powder is lighter, and the leather is flat and thin. In view of neutralization, the tanning temperature of tanning leather can reach the effect of industrial chromium powder. The wastewater produced by retanning, dyeing and fatliquoring processes contains low Cr~(3), and its components are complex and difficult to deal with. The bioflocculants prepared by microbial fermentation from straw were used to remove Cr~(3 from the simulated chromium-containing solution. The results showed that when the temperature was 30 鈩，

本文编号：1669184