Kinetic Study of Congo-Red Photo-Catalytic Degradation in Aqueous Media Using Zinc Oxide as Photo Catalyst Under Led Light

Abstract

The kinetic of photo catalytic degradation of Congo red dye using semiconductor in aqueous solution of ZnO has been studied. All photochemical experiments have been carried out in quartz photo cell 25ml capacity and the solvent used for all experiment was distilled water (D. W). The influence of temperature has been investigated as well. Spectrophotometric method was utilized for this work. Degradation kinetic has been done for absorption peak of Congo red at 497 nm and 344 nm. Different method was applied for this purpose, and the results show that the degradation of Congo red was first order at 497nm and zero order at 344 nm. The degradation of CR dye were increased by increasing temperature from 20 oC to 40 oC and then degreased at 50 oC and this is due to desorption that occur at the semiconductor surface while; in case of 10 oC the rate constant was higher than 20 oC. However, when changing the concentration the rate constant dose not changed regularly, this perhaps due to the fact that it does not follow the same order throughout the degradation process, and it does not obey Arrhenius law of activation energy.

Silver-Loaded Carbon and Phosphorous Co-Doped Boron Nitride Quantum Dots (Ag@CP-BNQDs) for Efficient Organic Waste Removal: Theoretical and Experimental Investigations

“…For this reason, the log–log graphical approach, as well as integral and deferential rate laws, have been used. The validity of the kinetic order can also be assessed using the correlation coefficient ( R 2 ) obtained from fitting curves, especially when R 2 is close to unity. ,, It shows that the degradation of tetracycline 375 nm is the second order with a R 2 value of 0.99 as shown in Figure B.…”

“…As indicated in Table , the influence of initial concentration on the rate constant, the rate constant of waste removal does not remain constant when the initial concentration is changed. The reason behind this is due to secondary photochemical processes that occur during photocatalytic degradation and also a change caused by the quenching process due to excimer formation, in which some intermediates absorb light and re-emit it as heat without initiating semiconductor photocatalysts, resulting in photons not reaching the photocatalyst’s surface. ,,,, …”

“…The reason behind this is due to secondary photochemical processes that occur during photocatalytic degradation and also a change caused by the quenching process due to excimer formation, in which some intermediates absorb light and re-emit it as heat without initiating semiconductor photocatalysts, resulting in photons not reaching the photocatalyst’s surface. 4 , 5 , 67 , 74 , 75 …”

“…Aromatic structures of most drugs, pesticides, and dyes are highly hazardous, carcinogenic, and mutagenic. , Photocatalytic degradation is one the methods for solving this issue, in which the photocatalyst absorbs electromagnetic radiation greater than or equal to the semiconductor’s band gap and excites electrons from the valance band to the conduction band. Thus, creating holes in the valence band (h+) and electrons in the conduction band, and as a result, reactive oxygen species (ROS), primarily hydroxyl radicals ( • OH) and superoxide radical anions (O 2 •– ), are formed at valance and conduction bands, respectively. − …”

Efficient photo-Fenton catalysis using magnetic iron nanoparticles decorated boron nitride quantum dots: theoretical and experimental investigations

“…Heterogeneous photocatalysis uses semiconductor oxides irradiated with UV, near-UV, or visible light at ambient temperature and pressure and in the presence of oxygen. 1,[5][6][7][8] Nano-sized photocatalysts, specically the zero-dimensional (0D) nanoparticles, exhibit enhanced photocatalysis efficiency compared to their bulk equivalents. This is caused by the presence of more active sites on the surface, enhanced electron-hole separation, a lower recombination rate, and broad absorption in the visible spectrum, which makes the photocatalyst harvest more energy.…”