固定化漆酶对水中邻苯二胺的去除研究

Research on the removal of o-phenylenediamine in water by immobilized laccase

以壳聚糖为载体,戊二醛为交联剂,采用交联法与吸附法相结合的方法对漆酶进行固定化,研究固定化漆酶在水处理中的应用,并进行了酶促反应的动力学和热力学分析,探讨了戊二醛质量浓度、交联时间、固定化时间以及漆酶质量浓度对固定化漆酶活性的影响。结果表明,漆酶固定化的最佳条件如下:戊二醛质量分数为5%,交联时间为8 h,固定化时间为6.5 h,酶质量浓度为20g/L。此条件下得到的固定化漆酶的比活力达到15 015.4U/g。利用制得的固定化漆酶对水中邻苯二胺进行处理。在最适温度50℃,最适pH=6条件下,利用12000U的固定化漆酶催化处理100mL质量浓度为200mg/L的邻苯二胺溶液,反应6 h后邻苯二胺的去除率达到94.8%。连续5次重复使用固定化漆酶处理邻苯二胺,6 h降解率均在60%以上。用自来水代替蒸馏水配制邻苯二胺溶液时,底物的去除率为55.1%,去除效果明显降低。固定化漆酶处理邻苯二胺反应属于一级反应,反应活化能约为44.1 kJ。

Wastewater treatment by using laccase-immobilized chitosan with glutaraldehyde as crosslinking agent was studied.The kinetics and thermodynamic analysis of enzymatic reaction were carried out.The effects of factors such as concentration of glutaraldehyde,crosslinking time,concentration of laccase and immobilizing time on the activity of immobilized laccase were investigated.The immobilization of laccase was optimized in conditions which could be specified as： 5% of glutaraldehyde concentration,8 h of crosslinking time, 20 g/L of laccase concentration and 6.5 h of immobilizing time.In the combined optimal conditions,laccase showed most promising immobilization where the activity of immobilized laccase was 15 015.4 U per gram carrier.In the second stage of research,the removal of o-phenylenediamine in aqueous solution by laccase immobilized on chitosan was studied.Factors such as pH value,temperature and adsorption on carrier that could influence the reaction were discussed in detail. The results indicated that the optimal pH for o-phenylenediamine removal by immobilized laccase was 6 while the optimum temperature for o-phenylenediamine removal by immobilized laccase was 50 ℃.The adsorption of o-phenylenediamine on carrier has a minor effect on the reaction and removal rate of o-phenylenediamine. The decrease of o-phenylenediamine level was resulted from the catalyzing capability of laccase in oxidation reaction.On the optimum condition,the removal rate of o-phenylenediamine can reach 94.8% when 100 mL of 200 mg/L o-phenylenediamine solution was oxidized by the aid of immobilized laccase which having activity of 12 000 U.The repeated continuous oxidation test of o-phenylenediamine carried out in the static system of immobilized laccase showed that the removal efficiency of immobilized laccase has maintained over 60% after 5 cycles of operation.Thus the catalytic efficiency of laccase was greatly improved when immobilized on chitosan.For the test of o-phenylenediamine removal in which tap water instead of distilled water was used as solvent,the removal rate of substrate by immobilized laccase was 55.1% showing obvious decrease of removal efficiency.The reaction of o-phenylenediamine degradation catalyzed by immobilized laccase was revealed to follow first-order reaction and the reaction activation energy was about 44.1 kJ.