Isolation And Screening Of Arsenic Removal Fungi And Preliminary Study On Arsenic Removal Mechanismon

Arsenic is widely distributed in nature,and the toxicity of arsenide is extremely strong.The arsenic pollution in water in China is seriously,and the incidents of arsenic poisoning frequently occur.The arsenic pollution in water has seriously threatened human health.The microbial method has become one of the potential technologies for the restoration of heavy metal pollution because of its advantages such as abundant and readily available strains,no secondary pollution,and low cost.In this paper,the arsenic-contaminated sediment in Datunhai,Honghe Prefecture,Yunnan Province is used as a sample,and a fungus with high removal rate of As³⁺in solution is isolated and selected.Morphological observation and ITS gene identification are performed to confirm that it is Penicillium chrysogenum.Single-factor experiment and response surface method were used to optimize the removal conditions of As³⁺,and the adsorption kinetics was studied under the optimal conditions.The mechanism of As³⁺removal was studied by means of scanning electron microscope and infrared spectrum analysis.The main research results obtained are as follows:?1?A single factor experiment was carried out on the strain to explore the removal rate of three conditions for the treatment time,pH value and the dosage of the bacteria.The results showed that the best removal effect was achieved at the time of 90min,the pH value of 5,and the dosage of 2 g/L respectively.?2?On the basis of single factor test,the optimal conditions were optimized by the response surface method.The optimal conditions were obtained:the time was 96min,the pH value was 5,the volume of the strain was 2.1g/L.The removal rate under this condition was 34.3%and the predicted value 35.01%was close.At the same time,the optimal conditions obtained by the response surface were consistent with the single factor experimental results.It shows that the response surface method has high accuracy in experimental optimization design.?3?Scanning electron microscopy and infrared spectroscopy were used to analyze the changes of bacterial surface and functional groups before and after removal of As³⁺.The results showed that the cell morphology was severely collapsing after As³⁺removal,which might be the result of As³⁺toxicity to the cell cells and the complexation and ion exchange between As³⁺and some groups on the cell wall.Infrared spectrum analysis showed that the O-H,N-H,C-N,C-H,C-O,and C-Br groups on the cell wall participate in the removal of As³⁺.?4?Adsorption kinetics showed that the adsorption process of As³⁺by Penicillium chrysanthemum could be simulated by the quasi-second-order kinetic model.Isothermal adsorption experiments show that the adsorption process conforms to the Langmuir isotherm equation,which shows that the adsorption process is monolayer adsorption.