Fabrication Of Pomelo Peel Biochar Supported MoS₂ Composite Material And Its Photodegradation For Organic Pollutants

Water is the origin of life.The direct discharge of toxic and harmful organic wastewater without treatment will lead to water pollution and have a negative impact on the environment on which we live.Photocatalytic oxidation technology has the advantages of high efficiency,energy saving,environmental protection,simple operation and so on.It is a kind of water pollution treatment process with broad application prospects.In the process of photocatalytic degradation,the selection of photocatalytic materials is very important.Molybdenum disulfide（MoS₂）is a substance that can absorb ultraviolet and visible light.When the absorbed energy is greater than its band gap energy,it will produce photogenerated electrons and holes,and then produce active substances to degrade pollutants.However,the aggregation and inefficient electron mobility of MoS₂ nanoparticles limit their application in photocatalytic degradation of pollutants.In order to improve the photocatalytic performance of MoS₂,the surface modification technology of biochar supported MoS₂ is an effective way.The white flocculation layer of pomelo peel is a kind of agricultural waste with high yield,good network structure and many functional groups.Therefore,the white flocculation layer of pomelo peel was used as raw material to prepare biochar（BC）,and BC was used as the matrix for loading nano-flower-like MoS₂ microspheres.A series of MoS₂-BC nanocomposites were prepared by adjusting the mass ratio of BC and MoS₂,which were used to efficiently remove ciprofloxacin（CIP）and Rhodamine B（Rh B）from water.When the mass ratio of BC to MoS₂ was 3:35,the prepared MoS₂-BC_3/35 composite had the best photocatalytic performance.When the dosage of MoS₂-BC_3/35 was 0.2 g/L and the initial concentration of CIP was 10 mg/L,the removal rate of CIP was 92.01%after90 min of illumination.In addition,the photocatalytic degradation efficiency of MoS₂-BC_3/35 for Rh B could reach 97.98%after 60 min(MoS₂-BC_3/35=0.2 g/L,Rh B=10mg/L),which indicated that MoS₂-BC_3/35 could effectively remove antibiotics and dyes.The characterization analysis showed that the photocatalytic performance of MoS₂modified by BC had been significantly improved,which was attributed to the fact that BC inhibited the agglomeration of MoS₂ nanoparticles and reduced the recombination rate of electron-hole pairs.In addition,the band gap of MoS₂-BC_3/35 was narrow（1.60e V）,and superoxide radicals（·O₂^-）,holes（h⁺）and hydroxyl radicals（·OH）were produced after illumination to degrade organic pollutants.According to the radical quenching experiment and electron spin resonance（ESR）,·O₂^-played a major role during the photocatalytic reaction,because the conduction band potential of MoS₂-BC_3/35（-0.81 e V）was lower than the potential of O₂/·O₂^-（-0.33 e V）.In contrast,h⁺and·OH had less influence on the photodegradation reaction system.In general,BC prepared by white flocculation layer of pomelo peel was a good carrier of MoS₂,which could avoid the accumulation of MoS₂,promote the separation of photogenerated carriers,inhibit the recombination of electrons and holes,thus improving the photocatalytic performance of MoS₂.Therefore,MoS₂-BC_3/35 is a promising photocatalyst owing to its eco-friendliness,high-efficiency and easy-preparation.