固相条件下研磨屑解毒六价铬机理及动力学规律研究

Mechanism and Kinetics of Detoxification of Cr(VI)by Abrasive Chips in Solid State

通过改变铬渣的粒径大小,在固相条件下将含铬废渣中的六价铬解毒后稳定化处置。研究了不同温度、pH、铬渣目数、含水率和初始浓度对研磨屑还原六价铬的反应动力学影响,通过实验验证:在pH=2~5,研磨屑与六价铬反应符合准一级动力学规律。pH为2时,速率常数是pH为3、4的1.63、2.47倍;铬渣粒径对反应体系的影响较为明显,R2大于0.98;目数为150目时,还原反应速率常数分别是目数为10、50目的12.1、4.8倍;在初始pH相同的条件下,体系含水率越高,还原剂研磨屑与含铬废渣粉末混合越均匀,固相反应速率常数越大;不同六价铬初始浓度的反应体系中,在铬粉目数相同的前提下,反应速率随六价铬初始浓度的增大而减小;在pH=3、含水率45%的条件下,反应速率常数随温度的升高而增大;温度为35℃时,反应速率常数分别是20℃、5℃的1.68、5.11倍。通过阿伦尼乌斯公式,建立六价铬固相还原反应体系中,反应速率常数随温度变化的函数关系方程。

The objective of experiments were determined that Chromium waste residue could be handled by changing size of Chromium slag in solid phase condition.The study of work was to indicate the effect of different temperature,pH,size of Chromium slag,water content and initial Cr(VI)concentration onkinetics of Cr(VI)reduction,results were indicated that iron filing and hexavalent Chromium was the pseudo-first-order kinetics reaction at pH 2.0~5.0.At pH 2,the kobs was 1.63,2.47 times the pH of 3 and 4.The influence of Chromium slag particle size was obvious in the reaction system,basically con⁃forming to the pseudo-first-order kinetics reaction,R2 more than 0.98,size of Chromium slag of 150 was 12.1,4.8 times the size of Chromium slag of 10 and 50.At the same initial pH,the water content of the system was more higher,iron filing and hexavalent Chromium was more evenly mixed,result of the kobs increasing.At the same size of Chromium slag,the rate con⁃stants of Cr(VI)reduction was gradually decreased with increasing initial concentration ratio of Cr(VI).In the condition of pH 3,water content 45%,the rate constants of Cr(VI)reduction was gradually increased with increasing temperature.In⁃creasing temperature could increase the kobs,and the kobs increased by 0.68 and 4.11 times when temperature was adjust⁃ed from 5℃to 20℃and 35℃.Arrhenius formula was used to develop the kinetics equation of the rate constants and temper⁃ature.