Study On Biosensing And Oxidative Degradation Of Bisphenol A In Water Based On Biochar As Catalytic Material

In recent years,the scientific community and the public focus on a new type of environmental pollutants which can simulate or resist the action of endogenous hormones.For this reason,these chemicals are known as"endocrine disruptors",including phthalates,plasticizers,surfactants,PCBs,dioxins,alkylbenzene（APS）,bisphenol A（BPA）,bromate flame retardants,polycyclic aromatic hydrocarbons（PAHs）and some pesticides.Bisphenol A（BPA）,its trademark,has been found in groundwater,surface water and wastewater at elevated levels,posing a significant threat to the environment and human health.Therefore,it is very important to detect and degrade bisphenol A in water.Biochar（BC）is a porous material produced by pyrolysis of biomass under anoxic condition.It has many pores,large surface area,environmentally friendly,low toxicity and rich functional groups.It has a broad application prospect in the field of enzyme immobilization and advanced oxidative degradation.In this study,based on the biochar with high conductivity and high catalytic activity,the biological detection system and oxidative degradation system of BPA were constructed.The research work carried out is as follows:（1）Pyrolysis of biomass at 900°C yielded highly conductive biochar materials,and nanoscale biochar particles（BCNPs）were obtained by centrifugation.The surface was subjected to weak oxidation and magnetic particle modification（Mag-BCNPs-COOH）,then the tyrosinase was loaded onto the surface of biochar（TYR/Mag-BCNPs-COOH）by covalent,cross-linking and precipitation methods,and the magnetic glassy carbon electrode（MGCE）was modified with this complex used as a sensing element to construct an electrochemical biosensor.It was found that the composite has good electrochemical activity,and the multilayer fixed composite（ML-TYR/Mag-BCNPs-COOH）had a much higher current response to BPA than a single layer（SL-TYR/Mag-BCNPs-COOH）.Under optimized conditions,BPA could be detected with high sensitivity between 0.01-1.01μM,and the detection limit is 2.78 nM.The biosensor shown good reusability,reproducibility,stability and anti-interference performance,and had achieved a reliable recovery rate in actual water sample detection.（2）The biochar catalytic materials（BC700,BC800,BC900）with different characteristics were obtained by controlling pyrolysis temperature,and their ability to activate PMS for the degradation of bisphenol A was studied.Due to the larger surface area and pore volume of BC900,more activation sites were provided for PMS activation.When the dosage of BC900 was 0.5 g/L and the concentration of PMS was 1.0 g/L,20 mg/L BPA can be degraded efficiently（60 min,100%）.The main oxidation species were singlet oxygen（¹O₂）and superoxide radical(O₂^-·).The experimental results shown that the persistent free radicals played a limited catalytic role,and the content of dissolved oxygen and the electron holes formed in the reaction played a certain role in promoting the efficient degradation of BPA.The electrochemical analysis showed that BC900 had superior electron transfer capability,and its activation efficiency for PMS was much higher than BC700 and BC800.And BC900/PMS system was capable of degrading BPA under a wide pH（1-11）and the presence of high concentration of anions and natural organic matter.The system showed a good degradation performance in the real environmental water,and it could be used in polluted water with phenol,Rhodamine B,methyl orange.Its degradation activity could be recovered to over 89%by reheating.