Study On Immobilization Of White Rot Fungi And Its Adsorption Performance On Dye Wastewater

With the increasingly severe environmental problems,water pollution has become a major global issue.Among them,dye wastewater accounts for 20% of the total global wastewater discharge,and these dye wastewater entering water bodies can cause serious harm to the ecological environment system and human health.Microbial immobilization technology is a wastewater treatment technology with fast treatment speed and high removal rate.In this thesis,the preparation of modified diatomite immobilized white rot fungus(De-HA/CTS-WRF)composite material and its adsorption performance for methylene blue(MB)were studied,and the adsorption behavior of the composite material for MB on a fixed bed adsorption column was discussed.At the same time,the preparation of ZIF-8 immobilized white rot fungus(ZIF-8-WRF)composite material and its adsorption performance for methyl violet(CV)were studied,The adsorption behavior of the composite material on a fixed bed adsorption column for CV was discussed.The main research content and results of this article are as follows:(1)Preparation and Adsorption Properties of De-HA/CTS-WRF CompositesA De-HA/CTS-WRF composite material was obtained by immobilizing white rot fungus on diatomite modified with chitosan and humic acid by cross-linking method.The characterization analysis shows that the composite material has a porous structure,contains a variety of functional groups that can be used to adsorb dyes,and exhibits electronegativity.The optimal adsorption conditions for MB by De-HA/CTS-WRF are 0.04 g composite material,4h adsorption time,and p H value of 6.Moreover,the adsorption behavior of De-HA/CTS-WRF on MB conforms to the Freundlich isotherm adsorption model,and the kinetic adsorption process conforms to the quasi second order kinetic model.This indicates that the adsorption process of De-HA/CTS-WRF on MB is a multilayer adsorption mainly dominated by chemical adsorption,which is a spontaneous exothermic process.The fixed bed adsorption experiment results show that the adsorption behavior of De-HA/CTS-WRF fixed bed in the initial stage conforms to the Adams Bohart model,and the adsorption behavior of the entire process conforms to the Yoon Nelson model.Both models can better describe the process of De-HA/CTS-WRF fixed bed adsorption of MB.(2)Preparation and Adsorption Properties of ZIF-8-WRF CompositesThe white rot fungus was immobilized on ZIF-8 by crosslinking method to obtain a ZIF-8-WRF composite material.The characterization experiments show that the ZIF-8-WRF composite has a porous structure,a large specific surface area,rich functional groups,and electronegativity.The optimal adsorption conditions for CV by ZIF-8-WRF were 0.02 g of composite adsorbent and 6 h of adsorption time.The adsorption process was not significantly affected by p H value.Moreover,the adsorption behavior of ZIF-8-WRF on CV conforms to the Langmuir isothermal adsorption model,and the kinetic adsorption process conforms to the quasi second order kinetic model,indicating that the adsorption process of ZIF-8-WRF on CV is a single layer adsorption mainly dominated by chemical adsorption,which is a spontaneous exothermic process.The experimental results of adsorption on ZIF-8-WRF fixed bed showed that the adsorption behavior of ZIF-8-WRF fixed bed at the initial stage conformed to the Adams Bohart model,and the adsorption behavior of the entire process conformed to the Yoon Nelson model.Both models can better describe the adsorption process of CV on ZIF-8-WRF fixed bed.