RESUMO
Our recent Communication (S. R. Khan et al., Chem. Commun., 2022, 58, 2208) suggested that CO2 can be used as a potential oxidant under light irradiation without using any catalyst for the oxidation of aldehydes to acids at room temperature. The Comment based on the published literature on the catalytic oxidation of aromatic aldehydes by CO2 and thermodynamical data argued on the realism of the experimental data.
RESUMO
A novel visible light-driven catalyst-free oxidation of aldehydes using CO2 both in batch and flow photoreactors to get corresponding acids along with the formation of CO in the effluent gas is described.
RESUMO
A non-edible waste, from biodiesel processing industry is being turned to carbonaceous material (biochar) using slow pyrolysis. The material was found to be amorphous with hydroxyl, methyl, carbonyl and carboxyl functional groups onto the surface. The influencing parameters, namely adsorbate concentration (0.05-5 mg/l), biochar loading (0.02-0.4 g), pH(3-12) and particle sizes (0.03-0.13 mm) were studied to observe the effect on the sorption of simazine using biochar. A multivariate optimization using central composite design in response surface methodology was performed employing desirability function. The optimized biosorption efficiency (B%) and capacity qe was found to be 91.98 % and 0.83 mg/g respectively with the optimized parameters as 3.76 mg/l of adsorbate concentration, 0.12 g of biochar loading, pH of 5.26 and 0.0535 mm of particle size. The simazine adsorption phenomena were found to be multilayer heterogeneous sorption based on Langmuir and Freundlich models. The kinetics investigation shows that chemisorption was involved for the transfer of simazaine to the surface of biochar with three distinct intra particulate diffusional zones. An adsorption process requires activation energy of 11.27 kJ/mol and the negative magnitude of ΔH* indicates the exothermicity involved in the process.