Removal Characteristics Of Tetracycline And Ciprofloxacin In The Wastewater By Ni-doped BiVO₄

Because antibiotics in the waste water has the character of wide origin,serious harm,not easy to be degraded,complicate composition,it is environmental friendly and cheap in cost to removal antibiotics by adsorption or catalytic oxidation methods.BiVO₄ and Ni-BiVO₄ were synthesized by microwave radiation with water,and XRD,FTIR,BET,PL,FESEM and DRS were used to characterize the films.A research was carried out on adsorptive and photocatalytic performance of tetracycline and ciprofloxacin which were common in antibiotics waste water by BiVO₄ and Ni-BiVO₄,mainly including removal influence factors,analyzing adsorption model,analyzing Ni-BiVO₄ before and after the removal of antibiotics to explore the structure activity relationship between structure of Ni-BiVO₄ and the performance of the removal of antibiotics,and to determine the main mechanism the removal of antibiotics,The main research results of this paper are as follows:?1?BiVO₄ and Ni-BiVO₄ were successfully synthesized by microwave-hydrothermal method.It was found that the analysis of characterization exhibited that two materials both have the features of BiVO₄:monoclinic crystal diffraction peak,specific surface was increased from 6.39 m2·g-1 to 12.49 m2·g-1,both pore volume and pore diameter were increased,most pore were pore diameter;IR absorption peaks stayed the same,fluorescence emission peak stayed the same and fluorescence intensity decreased illustrating that recombination rate of electrons and holes decreased,the shape of BiVO₄ changed from elliptic balls to bar and particle size bigger was bigger,and the content of Ni was 5.08 wt%.?2?During the choosing experiment of removing tetracycline and ciprofloxacin,compared with the unmodified BiVO₄,Ni-BiVO₄ had advantage in adsorbing tetracycline and ciprofloxacin,but the catalytic effect was so weak,which illustrated that a strong adsorption may effect promotion of the efficiency of photocatalysis.The conclusion is shown that the main removing effect of tetracycline and ciprofloxacin came from adsorption.?3?During the adsorption process of antibiotics by Ni-BiVO₄,adsorption efficiency was first up and then came to a balance with increase of adsorption dosage,and the best removal rate were 89%and 82%.While initial antibiotics concentration rising,adsorption efficiency decrease continuously;Adsorption efficiency increased first and then decreased under initial solution tetracycline pH 2?13 and reached to the highest under solution tetracycline pH4?7,while that for ciprofloxacin reached to the highest under solution ciprofloxacin pH5?8;Cu²⁺,at the lower concentration stimulated,but,at the higher concentration,inhibited the adsorption of antibiotics,and showed a stronger inhibition to ciprofloxacin.?4?The adsorption process of antibiotics by Ni-BiVO₄ followed the Langmuir adsorption model indicating that it is a monolayer adsorption reaction.The adsorption antibiotics on Ni-BiVO₄.was in accordanced with the pseudo-second-order model showing adsorption was first a fast reaction and then came to a balance;The main sorption mechanisms contain Van der Wals forces,?-? electron coupling and microporous fixation.?5?The results revealed that Ni-BiVO₄ adsorb capability higher than BiVO₄ which had not been modified.It is necessary to obtain more efficient materials by enhancing the photocatalytic activity to further achieve the goal of completely degrading antibiotics.It provides options for developing new preparation technology of modified BiVO₄ and the removal of antibiotics.