Horseraqdish Peroxidase Immobilized On Attapulgite Clay For Phenol Wastewater

Horseradish peroxidase can catalyze the oxidation of hydrogen peroxide and phenolic compounds to produce free radicals which can occurs polymerization to produce polymeric compounds, so that phenols can be removed from water. In this paper, attapulgite clay as raw materials, attapulgite clay carrier was prepared to immobilize horseradish peroxidase. The immobilized enzyme was used in the removal of phenols in wastewater. And it's proved that good results were achieved. In the thesis a systemic research is to be carried out in these aspests:the preparation of attapulgite clay carrier, the modification of attapulgite clay carrier, the optimal immobilization conditions for horseradish peroxidase, optimal reaction conditions choosing for immobilized enzyme in the removal of phenols from wastewater. Main research work are as follows:(1) The attapulgite clay carrier preparation conditions were identificated. Sodium silicate and starch were added in attapulgite clay with sodium silicate as binder starch as pore forming material. Granulation was calcined to prepare attapulgite clay carrier. With dissipation rate as indicator, the attapulgite clay carrier preparation conditions were determined. The result showed that the amount of sodium silicate was 9%; the amount of starch addition was 20%; calcination temperature was 550℃; calcining time was 1h.(2) The surface of attapulgite clay carrier was modified by KH-570. With immobilization yield of horseradish peroxidase as indicator, the modified concentration of the KH-570 was investigated. The result showed that the optimal modified concentration was 0.6%, the modification of attapulgite clay carrier can clearly enhanced the immobilization yield of horseradish peroxidase.(3) Horseradish peroxidase was immobilized on the modified attapulgite clay carrier. With immobilization yield of horseradish peroxidase as indicator,the optimal immobilized conditions was investigated. The result showed that the amount of carrier was 1mg/U; the immobiliation pH was 5.0; the immobilization time was 1.5h.(4) The immobilized enzyme was used in treatment of phenolic wastewater. The enzymatic reaction time, increase the amount of enzyme, phenol concentration, H2O2 addition were investigated by the impact of enzyme treatment.The result showed that the optimal reaction time was 1.5h; enzyme concentration 4.1U/mL; the optimal phenol concentration of 100mg/L; the optimal molar ratio of H2O2 and phenol is 1:1. Under the optimal condition, the recycling of the immobilized enzyme was investigated. the removal efficiency of phenol can reach 62.3% affter immobilized enzyme was used six times.