Abstract: Biodegradation extent of several ordinary alkyl xanthate collectors was determined according to the testing standard for biodegradability of surfactants ( GB/T15818-2006) , and the kinetic model of biodegradation was also discussed. Meanwhile, the impact of molecular structure on biodegradability was studied as well. The results indicates that under the laboratory conditions, the biodegradation extent of ethyl xanthate, isopropyl xanthate, n-butyl xanthate, isobutyl xanthate, n-amyl xanthate can reach at 96. 36% , 81. 76%, 73. 74%, 63. 37%, 60. 30% in 8 days, respectively. All of their aerobic biodegradation follows the first order enzyme reaction kinetics equation. The biodegradation and rate constant of alkyl xanthates with different structure are comparatively different, the rate constant of collectors follows the order of k_ethyl >k_butyl > k_amyl > k_isopropyl > k_isobutyl . With an increase in length of carbon chain and number of alkyl lateral chain, the biodegradability of the collectors decreases, while the disappearing time (DT-90) and half-life time ( t_1/2 ) of the collectors increase. Comparing to the alkyl chain length, the branch has a more significant effect on the degradability of alkyl xanthates. Through the preliminary study of the biodegradation mechanism of xanthates, it is found that CS₂, ROCSSH and thiocarbonate are the main products of biodegradation of xanthates and a small amount of oil-like dixanthogen droplets are also produced.

Key words: alkyl xanthates, biodegradation extent, degradation kinetics, mechanism

摘要： 根据表面活性剂的生物降解度评价标准(GB/T15818?2006)试验方法, 对几种常见的烃基黄药捕收剂的生物降解度进行了测定, 并探讨了生物降解动力学模型, 考察了分子结构对生物降解度的影响。研究结果表明: 在实验条件下, 乙基黄药、正丁基黄药、正戊基黄药、异丙基黄药、异丁基黄药在第 8 天的生物降解度分别为 96. 36%, 81. 76% ,73. 74% , 63.37%, 60.30%, 它们的好氧生物降解过程都符合一级酶反应动力学。不同烃基黄药的降解度和降解速率随结构的变化较大, 其降解速率大小顺序为: k_乙基 >k_正丁基 > k_正戊基 > k_异丙基 > k_异丁基, 其生物降解度则随化合物中碳链长度和烷基支链数的增加而减小, 其消失时间DT-90 和半衰期( t_l/2 ) 则随之而增大。相对碳链长度来说, 分支度对烃基黄药的生物降解度的影响更为显著。通过对黄药生物降解机理初步探讨发现: 烃基黄药生物降解的主要产物为 CS₂ , ROCSSH 和单硫代碳酸盐, 同时有少量油状液滴双黄药生成。

关键词: 烃基黄药, 生物降解度, 降解动力学, 机理