| Polycyclic aromatic hydrocarbons(PAHs) are one of the main chemical contaminants in aquatic environment. It attracts great attention because of its wide range of sources and toxic damage. At present, there are some methods for PAHs treatment, such as physical adsorption, extraction, separation, chemical oxidation and biological degradation. However, these methods have more or less defects in the aspects of cost control, processing time period and the threat of repollution, which makes the treatment of sudden PAHs pollution unsatisfactory.Bioenzymes have a significant advantage in dealing with sudden PAHs contamination because of its the high catalytic efficiency, mild reaction conditions, adjustable reaction conditions, short processing cycle, convenient storage, rapid transport and can be quickly put into use at the first time. All of these reasons for free enzymes : relatively high price, difficult recovery, was unable to avoid the secondary pollution, which greatly limit the free enzyme in clearing PAHs contamination in natural waters applications.Compared with the free enzyme, immobilized enzyme has some advantages such as reduce the cost of the enzyme, better stability, easy separation from the reaction system,so it become the new darling of the modern industrial enzymology application. At present, immobilized peroxidase, a higher catalytic efficiency enzyme, hydrogen peroxide is used as a substrate,is the main application to reduce PAHs. However the H2O2 has a strong oxidation, which can cause water harm, when it directly add to the water.In this paper, α-Amylase,GOD and Hb was immobilized on the amino-modified silica-coated superparamagnetic nanoparticles,which prepared magnetic actuation three enzymes reactors. Controled of the proportion of each enzyme and its orientations for efficient conversion the intermediate and low leakage. Under the premise of aquatic biosecurity, to solute PAHs contamination effectively. This immobilized enzyme can be release, recover and actuation with alternation magnetic field.The key of this paper is the intermediate products, glucose and H2O2, efficientive conversion. By adjusting the proportion of three enzymes and spatial positional relationship in the reactor, under the premise to improve the catalytic ability of the reactor, reduce intermediate product leakage. Prepared magnetic actuation three enzymes reactors at the molar ratio of α-Amylase, GOD, Hb is 55:40:45. Without external magnetic, 6mg/ml preparation into the reaction for 3 hours, the rate of starch hydrolysis is more than 81%,then ABTS removal rate is more than 67%,which exhibits the best catalytic performance and the lowest intermediate leakage capability:monolayer magnetic actuation three enzymes reaction system, the leakage of intermediate product of glucose concentrations below 80mg/L and H2O2 concentration below 0.5mg/L; compared to monolayer, double layers magnetic actuation three enzymes reactor has a lower probability of intermediate leakage which the leakage of glucose and H2O2 were 20% and 35% of the monolayer system respectively. Presence of magnetic field, the activity of Hb in the reactor showed a significant enhancement, and the three enzyme reactor showed a better PAHS removal rate and lower intermediate product leakage. Besides that,the immobilized enzyme was stabilized with the silica-coated magnetic nanoparticles.After eight times reuse, the immobilized enzyme occurred better recovery and stability of activity. The immobilized enzyme has been kept at 4 two months, no significant change has been detected.℃... |
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