Preparation Of Natural Ilmenite/Biochar Composites And Their Removal Research For Oxyfluorfen In Water

Ofloxacin（OFL）is the typical representative of quinolone antibiotics,which is widely used in the prevention of diseases in humans and animals.Due to its difficult biodegradability,ofloxacin is currently detected in oceans,lakes and rivers around the world,posing serious threat to human health and the ecological environment.Biochar made from agricultural waste is widely used for the removal of oxfloxacin from water due to its low cost and simple preparation,which is mainly used in the adsorption and activation.However,the single oxygen-containing functional group on the surface of biochar limits its adsorption capacity,while the easy inactivation and reusability of active sites on the surface of biochar also limit its application in activation.Therefore,it is crucial to modify biochar to enhance its adsorption or activation capacity.In this paper,the natural ilmenite with photoactivation potential and corn stover are used as raw materials to prepare new green and environmentally friendly composite materials,in order to enhance the adsorption performance of the composite and further develop its photoactivation capacity.This will provide theoretical guidance for the effective removal of antibiotics from water and provide new ideas for the resource utilization of agricultural waste and the application of natural ilmenite in water pollution engineering.The main research and findings were as follows:（1）A natural ilmenite/biocarbon composite（IB）with good adsorption properties was prepared by high-temperature oxygen-limited pyrolysis and used for the removal ofloxacin from water.The results of characterization analysis showed that IB had more abundant surface functional groups and surface active sites compared with biochar（BC）.The experimental results indicated that the adsorption process of IB on ofloxacin was a chemisorption process,which was spontaneous entropic heat absorption process.Among the different scaled composites prepared,IB5 had the most excellent adsorption capacity and stability,and the removal rate of OFL was 1.6times higher than that of BC.IB5 had excellent interference resistance which could remove more than 90%of OFL in the p H range of 2.0-10.0.At the same time,it was difficult to influence the adsorption capacity of IB5 by SO₄^2-、Cl^-、NO₃^-and other ions in the solution.The mechanistic study indicated that the adsorption process of IB was a synergistic result of hydrogen bonding andπ-πinteractions.（2）To gain insight on the application potential of IB,the ability of IB in photocatalytic activation of peroxymonosulfate（PMS）systems was discovered by adjusting the ratio of natural ilmenite and biochar.Degradation experiments showed that IB had excellent photocatalysis-PMS activation,with the best performing material（IB2,dosed at 1.0 g/L）achieving 95.67%degradation after 40 min reaction with OFL（20 mg/L）under visible light irradiation and PMS concentration of 0.5 m M.It was found that the IB2 photocatalytically activated PMS degradation of OFL was dominated by the radical pathway and had a synergistic degradation process of non-radical pathway at the same time.The impact experiments demonstrated that IB2had good stability in the p H range of 2.0-10.0 and also had good resistance to inorganic components(SO₄^2-、Cl^-、NO₃^-)and organic components（humic acid,HA）in solution.Meanwhile,IB2 could degrade many types of pollutants.（3）Sodium alginate（SA）was selected as the cross-linking agent,and the best reactivity of powdered IB2 was used as the raw material to prepare composite gel spheres（SA@IB2）.The performance of SA@IB2 for photocatalytic activation of PMS for OFL degradation was investigated by static and dynamic aqueous（continuous flow）experiments.The experimental results showed that the best degradation was achieved when the SA@IB2 was dosed at 15 g/L and the PMS concentration was 0.6 m M,which could degrade 97.12%of OFL（20 mg/L）after 60min of reaction.Repeatability experiments showed that the increase in the number of cycles would lead to the clogging of pores on the surface of SA@IB2,which affected the adsorption capacity and reaction rate.Further extension of the reaction time of SA@IB2 to 100 min still showed more than 95%degradation of OFL（20 mg/L）.In addition,SA@IB2 had good interference resistance and application potential,so that the inorganic or organic components in the actual water（tap water and Yellow River water）had weak influence on the degradation of OFL.