改性蒙脱土固定化辣根过氧化物酶对2,4,6-三氯苯酚的催化去除及其影响因素研究

Removal and influences of 2,4,6-trichlorophenol catalyzed by horseradish peroxidase immobilized on modified montmorillonite

以黄腐酸改性的蒙脱土为模板固定辣根过氧化物酶(Horseradish peroxidase,HRP)研究其催化去除水中2,4,6-三氯苯酚(2,4,6-trichlorophenol,2,4,6-TCP)的效果及其影响因素,并与自由酶催化反应做对比研究了不同催化时间、pH值、温度和固定化HRP浓度对催化反应的影响,以及对固定化HRP催化降解2,4,6-TCP进行了动力学分析,考察了固定化HRP的重复使用性和储存稳定性.结果表明:黄腐酸活化的蒙脱土固定的HRP具有很高的生物活性,固定后的HRP活性高达112 U·g-1;固定化HRP催化降解100μmol·L-12,4,6-TCP,20 min后对2,4,6-TCP的去除率已达到96%,催化降解速率高于自由酶;HRP经过黄腐酸改性的蒙脱土固定化后,催化降解2,4,6-TCP的最优pH值为6;固定化后的HRP其催化反应的适宜温度范围(10~50℃)比自由酶(30~50℃)更宽泛.改性蒙脱土载体固定HRP对2,4,6-TCP的去除作用主要是由固定化HRP的催化作用引起的,吸附去除率贡献仅达到0.77%,氧化去除率仅为2.81%.固定化HRP催化2,4,6-TCP的Linerweaver-Burk反应动力学参数中最大反应速率Vmax=7.14×10-4mol·L-1·min-1,米氏常数Km=1.56×10-3mol·L-1.在储存稳定性方面,固定化HRP的储存稳定性极高,50 d后依然可以保留80%的活性.

Horseradish peroxidase( HRP) was immobilized on montmorillonite modified by fulvic acid for 2,4,6-trichlorophenol( 2,4,6-TCP) removal in aqueous solution. The effects of several factors,such as reaction time,pH,temperature and concentration of immobilized HRP on 2,4,6-TCP removal were discussed in detail in comparison with those of free HRP. The degradation kinetics of 2,4,6-TCP catalyzed by immobilized HRP,reusability and storage stability of immobilized HRP were also investigated. The results indicated that HRP immobilized by montmorillonite activated with fulvic acid possessed high biological activity and could reach up to 112 U·g-1. The removal efficiency of 2,4,6-TCP( 100 μm) reached 96% after 20 minutes,and the catalytic degradation rate of immobilized HRP was higher than that of free enzyme. The optimized pH of immobilized HRP was 6 for the removal of2,4,6-TCP. The suitable temperature range( 10 ~ 50 ℃) of immobilized HRP in the catalytic degradation of 2,4,6-TCP was broader than that of free enzyme( 30 ~ 50 ℃). Removal of 2,4,6-TCP by HRP immobilized on montmorillonite was mainly caused by the reactivity of immobilized HRP,with the adsorption removal of only 0. 77% and oxidation removal of 2. 81%. The kinetic parameters of 2,4,6-TCP catalyzed by immobilized HRP were Vmax= 7. 14×10-4mol·L-1·min-1and Km= 1. 56 × 10-3mol·L-1. The storage stability of immobilized HRP was high,with 80% of the reactivity of immobilized HRP retained after 50 days.