从铬鞣废液中提取氧化铬绿的研究

【作者】 樊卫华；

【导师】 汤克勇； 屈凌波；

【作者基本信息】 郑州大学 ， 分析化学， 2002， 硕士

【摘要】 制革工业铬鞣废液中铬的回收与利用，是目前国内外制革行业中较难解决的课题之一。 铬鞣废液中含有大量的三价铬离子和六价铬离子，若以Cr₂O₃计，铬含量高达3000-6000mg/l。这样高浓度的含铬废液的排放，不仅严重污染环境，严重影响人类的健康，而且极大地浪费了优良的铬资源。 对铬鞣废液中三价铬的处理和回收，主要有循环利用法、吸附回收法、化学絮凝沉淀法、加碱沉淀法等。前三种方法在实际应用过程中，均存在有一定的缺陷和不足。加碱沉淀法可以有效地除去水中的铬，但也存在着所得Cr（OH）₃的二次污染问题。本文研究了加碱沉淀法的实验条件，找到了最佳的加碱沉淀方案。结果为：加碱沉淀法回收的处理和回收效果受沉淀剂、pH值和温度等因素的影响，用NaOH做沉淀剂，pH值宜控制在8.5附近，温度控制在40℃左右，则沉淀为絮状，且水质好，铬鞣废液中三价铬的去除率可高达99.9％。 本文在研究高温下煅烧Cr（OH）₃制取氧化铬绿的最佳条件方面也做了系统的研究，探索了制备高纯度Cr₂O₃的温度和时间对结果的影响：在1200℃煅烧7个小时，即可得到纯度为98.6％的Cr₂O₃，达到国家石油化学工业部化学纯标准（98.5％）；在1300℃煅烧7个小时，可得纯度为99.0％的Cr₂O₃，达到国家石油化学工业部分析纯（99.0％）标准。 本研究项目的成功与应用，可望解决铬鞣废液中铬的污染和铬资源的巨大浪费问题，又为我国这个贫铬国家找到了一个制取Cr₂O₃的新途径。此法的优点是回收三价铬离子较完全，沉淀、过滤、煅烧、测试等后处理的条件要求不高，便于推广，相信会在制革工业界有较好的应用前景。更多还原

【Abstract】 Wasted chrome tanning liquors in tanneries are processed for the abstraction of chromium from it. How to use the chromium in it is one of the great problems faced the leather industry all over the world. There is plenty of chromium in it. The amount of chromium may be 3000-6000mg/l as the count of Cr2O3. The wasted chrome tanning liquors not only pollute the environment, but also does harm to human being’s existence. In the meantime, a large amount of chromium resource is wasted.Several such useful techniques to process wasted chrome tanning liquors in tanneries as recycling, adsorbing, precipitating with flocculating agent, and precipitating with alkali are introduced. The first three means have many defects in the application, the last one has stopped only at the stage of getting Cr(OH)s.In the paper, experiments have been done to study the method of precipitating with alkali. If NaOH is used as precipitating reagents, pH value should be controlled at about 8,5, and precipitating temperature should be controlled at 40. At this time, Cr(OH)3 is a flocculent precipitation, the water processed reaches high quality, and the de-chroming rate of wasted chrome tanning liquors may be up to 99.9% in the proper condition. How to get Cr2O3 from Cr(OH)3 is studied and the best reaction condition is obtained at last. The conclusions show that the experiment may be affected by the reaction time and reaction temperature. If Cr(OH)3 is scorified at the temperature 1200 for seven hours , the purity of product may be 98.61%.By the way, the standard of chemical purity set by the National Chemical Industry Ministry is 98.5%; if Cr(OH)3 is scarified at the temperature of 1300癈 for seven hours, the purity of product can be 99.0%, and reach the standard of analytical purity(99.0%).By this method, both the problem of the pollution of wasted chrome tanning liquors and waste of resource are resolved. A new way of making CO is found in our country with rare chromium resources. The advantage of this method is perfect and the process is easy. Therefore, the method is easy for application. The perspective of it is wonderful, as is worthwhile of being believed.更多还原