Immobilization Of Cutinase On Polyethylenimine Modified Nanoporous Gold And Its Adsorption And Degradation Of Phthalic Acid Esters

Due to the development of human society, more and more persistent organicpollutants was released into the environment, phthalates persistent organic pollutantsis particularly problematic. Phthalates is an environmental endocrine disruptors whichinterfere with animal and human endocrine function, affect the biological hormonesynthesis, secretion, transport, binding, metabolism, reproduction, development andsexual behaviour. After entering the human and animal body, they will cause multipleorgan damage and serious harm to the health of the organism, even causeinter-generational impact by the placenta and lactating, besides, it might causecarcinogenesis and teratogenic effect.Phthalates is hard biological degradation organic compounds in natural state, therates of hydrolysis and photolysis are very slow, and have a longer half-life ofhydrolysis and photolysis. In recent years, how to provide a fast and efficient but alsolow cost method to deal with phthalates contaminants has become the focus of currentresearch content. Combined adsorption with biodegradation to deal with thephthalates organic pollutant was very effectively. Phthalate, di (2-ethylhexyl) ester(DEHP) is the world’s largest amount of phthalate plasticizers which is harmful tohuman health, this experiment used DEHP as the representative to study theadsorption degradation characteristics.Cutinase can hydrolyze soluble ester, insoluble triglycerides and polyester, canalso effectively degrade DEHP, and its degradation products are non-toxic, but thedegradation performance of free cutinase is restricted. Nanoporous gold is a newnano-porous metallic materials, which attracts more and more attention, due to itshigh porosity, large surface area, good conductivity, strong adsorption, light weightand easy to flexible control its structure etc. It was widely used in the field ofmacromolecular catalysis, adsorption and separation and biological fixation.Therefore, this study utilized polyethylenimine-modified nanoporous goldimmobilized cutinase, in order to improve the adsorption degradation of DEHP. Fieldemission scanning electron microscopy was used to carry out the adsorbentcharacterization of polyethylenimine-modified nanoporous gold immobilized cutinase,it was found that there was a uniform distribution of nano-porous structure, thecutinase was uniformly fixed on polyethylenimine-modified nanoporous gold surface. Effectively solved the problems that the free cutinase activity was not sufficientlystable under the operating conditions; cutinase is very sensitive to the environment; itis difficult to be recovered from the water system and separated from the substrate andproduct; the material cannot be reused. Fourier transform infrared spectroscopy andXRD-ray diffraction characterization were used to confirme cutinase was successfullyimmobilized on polyethyleneimine modified nanoporous gold surface andimmobilization process did not change the structural characteristics of the cutinaseand nanoporous gold.Further analysised the factors affecting the adsorption and degradation efficiencyis needed, such as adsorption time, pH, temperature, adsorbent dosage and complexpollution in the presence of heavy metals, the adsorption and degradation of DEHPconditions by polyethyleneimine immobilized nanoporous gold adsorbent cutinasewere optimized to determine the optimum adsorption degradation conditions, improvethe processing efficiency of DEHP. The results showed that the optimum adsorptionconditions was at pH8.0and at temperature60℃, the optimum adsorption time was12h, the optimum adsorbent dosage was10mg/L. Under optimum adsorption conditions, when the DEHP concentration for30mg/L, the adsorption capacity was128.6mg/g, which is much higher than that of the conventional biological adsorbent andsimple adsorbent material. Additionally， it could deal with low concentration ofDEHP and low concentration of heavy metals combined pollution. Besides,immobilized adsorbent material could be reuse more than once, the adsorption ratewas about85%after repeated5times, and still remained at about80%aft er8timesrepeated use.