Preparation Of BiOCl Ultrathin Nanosheets Composite Photocatalysts And The Research On Performance Over Photocatalytic Degradation Of Tetracycline Hydrochloride

The incremental accumulation of antibiotic residues in water exacerbated the environmental degradation.Therefore,it is urgent to develop a practical method to effectively remove antibiotics in the environment.Photocatalytic technology has large advantages of non-toxic,steady behaviours and cheep cost,which can be well devoted into the degradation of organic matters under sunlight irradiation.Among various photocatalysts,BiOCl has been attracted over the peculiar layered distribution and field effect.However,the narrow in spectral absorption and the high recombination rate among charge carriers limit the practical application of BiOCl,which need to be modified in the further research.In this paper,the thickness of BiOCl crystal was droped into ultrathin scale,which improved the vacancy defects in concentration.Meanwhile,the introduction of trigonal selenium can not only enhance the optical absorption of photocatalysts in visible-light region,but also promote the separation of phto-generated carriers by steering holes migration in a special direction.Subsequently,we introduced the biochar derived from bamboo leaves as the substrate of BiOCl ultrathin nanosheets,which improved the adsorbability of the whole system as well as the electron mobility of BiOCl.Finally,the introduction of rare earth metal ions Er³⁺into the C/BiOCl materials realized the architecture of up-conversion with photocatalytic materials,which lifted the utilization of optical energy in long-wave region.The following summarized the works in this paper:1.The selenized cadmium quantum dots as the precursors of t-Se nanorods were prepared by the method of water bath,and the quantum dots were then dissociating and germinating on the surface of BiOCl ultrathin nanosheets to form t-Se/BiOCl photocatalyst by a solvent thermal method.The composites were evaluated through several measuring instruments,and the photocatalytic investigation of tetracycline hydrochloride with the illumination of visible light was then carried out.The results showed that the defect state was formed in BiOCl due to its ultrathin thickness,which promoted the formation of heterojunction with t-Se.And this composite has efficient performance in photocatalytic degradation.Moreover,the optimal visible-light photodegradation rate of tetracycline hydrochloride reached 85.7%in 90 minutes as the mass fraction of t-Se nanorods at 20%.2.The bamboo leaves were prepared into biochar with rich pore structure by pyrolysis.The mannitol was then used as solvent to prepare the precursor of BiOCl,the x wt%?x=10,15,20?of biochar were mixed with BiOCl precursor,and C/BiOCl composite photocatalysts were obtained by solvent thermal process.These materials were assessed via multiple test devices and the photocatalytic investigation of tetracycline hydrochloride was also carried out via the illumination of visible light.The results showed that while the introduction of green biochar in BiOCl system,the maximum absorption capacities of all composites were more than 9.36 mg/g in 60minutes under dark condition.In fact,as a good electron acceptor,biochar realized the valid transfer of photogenerated electrons.More importantly,the optimal visible-light photodegradation rate of tetracycline hydrochloride reached 71.8%in 90 minutes as the mass fraction of biochar at 15%.3.The up-conversion C/Er³⁺:BiOCl composites were synthesized by solvent thermal process.The C/Er³⁺:BiOCl photocatalysts were then characterized by means of various instruments to further investigate the photocatalytic mechanism.The results showed that BiOCl was a favorable doped matrix for the rare earth metal ions,and the up-conversion fluorescence structure can be fabricated between BiOCl and Er³⁺.With the effective absorbtion of long-wave photons,Er³⁺was stimulated to make energy transition and converted low-energy incident photons into high-energy emission photons,which liberated the short-wave light capability of BiOCl.Moreover,the synergistic effect with biochar promoted the enhancement of photocatalytic activity.And the maxium photodegradation rate of tetracycline hydrochloride in 90 minutes was successfully raised to 89.2%under visible-light irraditation when doping amount of Er³⁺was 3 mol%.Furthermore,its rate can also reach 44.3%with the light illumination of wave lengths over 600 nm in 90 minutes.