| BiOCl,a new type of indirect band gap semiconductor,with the unique open layered structure,is considered to be a promising photocatalytic material,which has attracted more and more attention.At present,most of the researches on BiOCl photocatalysts focus on nano-scale powder catalysts,that are easy to agglomerate and deposit,and difficult to recycle.These problems greatly limit the practical application of Bi OCl photocatalysts.To solve the above problems,Ni?OH?2 doped activated carbon?Ni?OH?2@ACSs?were successfully prepared on the basis of optimizing the preparation conditions of the activated carbon?ACSs?,then we coat BiOCl onto the Ni?OH?2@ACSs by impregnation method to gain the Ni?OH?2@ACSs/BiOCl composite photocatalyst.The effects of the Ni?OH?2@ACSs/BiOCl preparation process on the photocatalytic activity are as follows.1.Preparation and Characterization of Phenolic Resin-based Activated Carbon Spheres?ACSs??1?The phenolic resin-based activated carbon spheres were prepared from 3-methylphenol and formaldehyde by suspension polymerization method.The effects of technical parameters including 3-methylphenol formaldehyde ratio,amount of HMTA,the catalyst type and stirring rate on particle size distribution were investigated deeply.By optimizing the process parameters,the proportion of phenolic resin balls with particle size?0.9mm can reach 89%.?2?The optimum preparation process of phenolic resin-based activated carbon ball is as follows: the molar ratio of m-cresol to formaldehyde is 1:1.3,the catalyst triethylamine is 1.5 mL,the dispersant polyving alcohol?PVA?and the curing agent hexamethylene tetramine?HMTA?is 1.5 g and 2.0 g,respectively.The reaction temperature is 98±1?,the stirring speed and reaction time are 500 r/min and 4 h,respectively.?3?The phenolic resin ball obtained by the above method was subjected to a carbonization-activation treatment to obtain a phenolic resin-based activated carbon spheres?ACSs?.BET surface area is 935 g/m2,the total pore volume is 0.412 g/m3,and the percentage of mesopores is 6.6%.2.Preparation and Photocatalytic Activity of Ni?OH?2@ACSs/BiOCl?1?During the preparation process of phenolic resins,we added x g?x=0,0.5,1.0,...,3.0?Ni?NO3?2·5H2O into the reaction system to get Ni-phenolic resins.After carbonization and activation process,we gained a series of activated carbon spheres that contain different qualities Ni?OH?2,denoted as x-Ni?OH?2@ACSs.By coating BiOCl onto the x-Ni?OH?2-doped activated carbon spheres?x-Ni?OH?2@ACSs?in impregnation method,we obtained x-Ni?OH?2@ACSs/BiOCl composite photocatalyst.?2?X-ray photoelectron spectroscopy?XPS?and Fourier transform infrared spectroscopy?FTIR?characterization indicate that Ni?OH?2 was successfully doped into the active carbon spheres.The BET calculations show that the addition of Ni?OH?2 makes the percent of mesopores increased.When x increases from 1.0 to 1.5,the mesopore rate increases from 24% to 39%.X-ray diffraction?XRD?and Scanning electron microscope?SEM?reveal that the BiOCl crystal has a well crystal structure with rod-like structure on the surface of activated carbon.?3?The photocatalytic activity of the x-Ni?OH?2@ACSs/Bi OCl composite catalyst was measured by degradation of resorcinol?RC?and methylene blue?MB?under simulated sunlight.It is found that the photocatalytic activity of x-Ni?OH?2@ACSs/BiOCl is significantly higher than that of ACSs/BiOCl,and among them the photocatalytic activity of 1.5-Ni?OH?2@ACSs/BiOCl is the best.After 50 min and 150 min,both phenol?RC?and methylene blue?MB?are completely degraded.We also studied the optimum conditions for degradation of 100 mL resorcinol: the amount of 1.5-Ni?OH?2@ACSs/BiOCl is 0.2 g and the initial concentration of resorcinol is 10 mg/L.?4?The experimental results show that the active species in the degradation reaction of resorcinol?RC?and methylene blue?MB?are h+ and ·O2-,and ·O2-is more active.The reasons for the increase of the photocatalytic activity by adding Ni?OH?2 are as follows: on one hand,the addition of Ni?OH?2 can adjust the pore size of the activated carbon spheres and increase the mesoporosity,so as to improve the adsorption of macromolecular organic pollutants.On the other hand,Ni?OH?2 can consume photogenerated holes in the photocatalytic reaction,inhibit the photo-generated electron-hole recombination,and generate more active species·O2-while Ni?OH?2 is oxidized to NiOOH to participate in the degradation of organic pollutants,and finally improving the photocatalytic activity. |
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