Preparation Of CdS And Research On The Photocatalysis Of Organic Dyes

Some traditional and new rising methods of dye sewerage treatment were summarized.By comparing them,photocatalysis was proved to be a specially applicable and predominant method when decomposing the dyes.Nano-CdS is widly used and therefore is synthesized in many different ways.Among those ways,the sol-gel method is a simply operating way which can also be applicable in composing photocatalyst.Refered to the others' researches about the composing conditions,chose preliminarily the conditions which may have influence on the decomposing process.In addition,the exterior conditions which may affect the decomposing process were screened out by making analogy between CdS and other photocatalyst.Use CdCl₂ and Na₂S to synthesize CdS nanoparticles firstly,and then research on the process of photocatalytic decomposition of methylene blue.The results of vacancy study and dark study show that cadmiun sulphide is a very efficient photocatalyst.Study on the effection of calcine temperature,[S^2-]/[Cd²⁺],dosage of dispersant and compose temperature in preparation of nano-CdS.The results told the optimal conditions of composing the cadmiun sulphide in order to improve the efficiency.CdS was characterized by XRD,SEM,UV-Vis spectrum,BET and IR spectrum.Then research on the process of photocatalytic decomposition of methylene blue. Study.on the effection of time,dosage of photocatalyst,consistency of MB,pH,etc by changing the conditions.A durable-test showes that cadmiun sulphide is a very efficient photocatalyst and it is durable in repetition.Then test the CdS on the other dye,the result showes that CdS also has high activity when decomposing other typical dyes.The thesis took kinetics analysis of the process MB being decomposed on the basis of anterior experimental data.MB was absorbed on nano-CdS in dark reaction,the results were used to imitate the Langmuir and the Freundlich absorption type.The process of photocatalysis shows that photocatalysis is first order kinetics reaction.The velocity constant increases as the intensity of light increases and the two of them have a linearity relation.The Arrhenius activation energy is 19.13 kJ/mol,and the affection of temperature is inapparent.Took spectroscopic analysis during the process and scaned the final productions by IR spectrum,and then speculated on the approach how the dye molecule being decomposed,in the end the mechanism of photocatalysis was discussed.