可见光下竹叶生物炭掺杂BiOBr_(x)Cl_(1-x)光催化降解罗丹明B

Photocatalytic degradation of rhodamine B by bamboo leaf biochar doped with BiOBr_(x)Cl_(1-x) under visible light

利用共沉淀法合成不同Br、Cl比例的BiOBr_(x)Cl_(1-x),并掺杂不同质量的竹叶生物炭制备复合光催化剂.利用扫描电子显微镜、X射线衍射仪、傅里叶变换红外光谱仪、紫外-可见漫反射和Zeta电位对材料进行表征.结果表明,100 mg竹叶生物炭掺杂BiOBr_(0.2)Cl_(0.8)的光催化效果最佳,光催化100 min可降解96.1%的罗丹明B溶液(RhB,10 mg·L^(-1)),光照120 min后RhB的矿化率达到59.6%.探究了催化剂投加量和溶液pH等因素对复合光催化剂可见光下降解RhB的影响.自由基捕获实验和电子顺磁共振结果显示,在降解中起主要作用的活性物种为·O_(2)^(-)和h^(+).生物炭的掺杂能够减小光催化剂的禁带宽度,增加光吸收范围,构建电子传输通道,阻碍光生电子-空穴复合,进而提高光催化效率.

BiOBr_(x)Cl_(1-x)photocatalysts with different ratios of Br and Cl were synthesized by a coprecipitation method,which were mixed with bamboo leaf biochar with different mass to prepare composite photocatalyst.The materials were characterized by scanning electron microscope,X-ray diffractometer,Fourier transform infrared spectrometer,UV-visible diffuse-reflectance spectra and Zeta potential.The results indicated that 100 mg bamboo leaf biochar doped BiOBr_(0.2)Cl_(0.8)showed the best photocatalytic performance,which could degrade 96.1%of 10 mg·L^(-1)rhodamine B(RhB)solution in 100 min,and the mineralization rate of RhB reached 59.6%after 120 min illumination.The effects of catalyst dosage and pH of solution on the degradation of RhB under visible light were investigated.Based on the radical trapping experiment and electron paramagnetic resonance,it can be concluded that the main active species in the degradation process were·O_(2)^(-)and h^(+).The doping of biochar can reduce the band gap of photocatalyst,increase the light absorption range,construct an electron transmission channel and hinder the photo-generated electron-hole recombination,then improve the photocatalytic efficiency.