Catalytic Oxidation of Nitrite to Nitrate in Aquas Solution by Carbonate-Activated Charcoal

Activated charcoals were prepared by activation with ۶۰۰ W microwave irradiation in combination with pretreatments of tamarind wood derived charcoal in boiling mixtures with NaOH (۱ g : ۰ g - ۱ g: ۰.۱۲ g). The samples were characterized by FTIR, XRD, SEM-EDS, and BET, and used for catalytic nitrite c oxidation under air atmosphere in the absence of light at ۳۰°C, pH ۶.۵, and ۱۲۰ rpm shanking for improved efficiency. The results show that the percent yields of tamarind wood derived activated charcoals (ACCs) were ۸۸.۵۱% - ۹۴.۶۶ %. The main carbonate compounds of ACCs are present in the materials after activation. Na+ ions and water molecules could be inserted into the graphitic layers during pretreatment and efficiently effected surface cracking of ACCs by ۶۰۰ W microwave irradiation. The surface cracklings and porosities of ACCs increased with increasing concentration of NaOH from ۱ M to ۳ M with optimum at ۲ M NaOH. The final products are mesopore materials containing macro and meso hole channels. It was found that the nitrite conversions exhibit high reaction rates and are completed within ۲۰ min. The reactions proceed via catalytic oxidations and their rates increase with increasing concentrations of NaOH activation, while nitrite conversions via the disproportionation reaction were inhibited.

کلیدواژه ها:

Microwave irradiation ، Sodium hydroxide ، Activated charcoal ، Catalytic oxidation ، Nitrite