Study of Pyrocatechol Absorption Efficiency from Aqueous Solutions using Pumice (Natural and Modified with Hydrochloric Acid)

Pyrocatechol in aquatic environment can be hazardous for living organisms and humans. Therefore, its elimination and prevention of its emission into the environment is very important. The purpose of this study was to evaluate the efficiency of pyrocatechol absorption from aqueous solutions using pumice (natural and modified with hydrochloric acid).
In this experimental study, pumice with Mesh 20-40 was used as adsorbent in 250 ml Erlyens as batch. The effects of the absorption parameters such as pH, contact time, adsorbent dosage, and the initial pyrocatechol concentration on adsorption were evaluated. Results were evaluated with Langmuir and Freundlich isoterms and first order and pseudo-second order kinetics.
Findings: The maximum absorption was obtained at the adsorption rate of over 90% for natural pumice and higher than 98% for pumice modified with hydrochloric acid, for 10 mg/l initial pyrocatechol concentration. The results showed that the adsorption by natural and modified pumice was increased with increasing contact time and adsorbent dose and reached equilibrium at 20 minutes. The adsorption of pyrocatechol by natural and modified pumice corresponded better with Langmuir isotherm model (for natural pumice R2 = 0.974 and for modified pumice R2 = 0.9988). In addition, the adsorption of pyrocatechol by natural and modified pumice clearly followed the pseudo-second order reaction (for natural pumice R2 = 0.9977 and for modified pumice R2 = 0.9788).
Pumice, due to its abundance, especially in Iranian mines, and low cost, can be used as adsorbent in pyrocatechol removal from wastewater. Therefore, pyrocatechol modification with chloric acid can be used as a suitable method for increased adsorption of pyrocatechol by pumice.