ABSTRACT
Textile industry dye effluent contains a mixture of different kinds of dyes. Many times, photocatalysis is targeted as a solution for the treatment of dye effluent from the textile industry. Many researches have been published related to the photocatalysis of single textile dyes but in the real-world scenario, effluent is a mixture of dyes. Magnesium oxide (MgO) is used as a photocatalyst to treat a mixture (binary solution) of Methylene blue (MB) and Methylene violet (MV) along with individual MB and MV dyes in this article. MgO shows remarkable photocatalytic activity at about 93 and 88% for MB and MV dye in binary solution within 135 min. Furthermore, to study the influence of process parameters, experiments are designed with the help of the central composite design (CCD), and Response surface methodology (RSM) is used to study the interactions between parameters. For this study, five parameters are selected i.e., Photocatalyst dosage, initial concentration of both dyes, time of exposure to the light source, and pH of the binary solution. The photocatalytic process is also optimized and finally optimization of process parameters is validated with an experiment. The result of the validation experiment is very close to the predicted photocatalytic activity.
ABSTRACT
The mechanochemical ball milling followed by heating at 650 °C for 5 h successfully produced the single-phase Bi2VO5.5 powder. Catalytic activity for methylene blue dye degradation was investigated. Raman spectroscopy and X-ray diffraction were used to confirm the phase formation. The sample's charge carrier transportation behavior was ascertained using time-dependent photocurrent analysis. The piezo-photocatalysis experiment yielded a 63% degradation efficiency for the ball-milled Bi2VO5.5 sample. The pseudo-first-order kinetics of the piezo-photocatalytic dye degradation are discerned, and the significant k value of 0.00529 min-1 is achieved. The scavenger test declares the h+ radical is the predominant active species during the piezo-photocatalysis experiment. Vigna radiata seeds were used in a phytotoxicity test to evaluate the germination index. The mechanochemical activation method facilitates reactions by lowering reaction temperature and time. The effect of improved piezo-photocatalytic efficiency on the ball-milled Bi2VO5.5 powder is an unexplored area, and we have attempted to investigate it. Here, ball-milled Bi2VO5.5 powder achieved improved dye degradation performance.
