Toxicologie environnementale et analytique

Removal of Nitrate and Nitrite Anions from Wastewater Using Activated Carbon Derived from Rice Straw

Abstract

Hassan A Hanafi and Sami M Abdel Azeema

Rice straw (RS) has been activated using Na2CO3. Activated carbon samples (ARSC) were characterized using N2- adsorption, elemental analysis, surface fractional dimension and pore volume to support the adsorption of nitrate and nitrite ions. The effects of various parameters such as solution pH, adsorbent concentration, contact time, temperature and initial nitrate and nitrite concentrations were examined. Various kinetics models including the Pseudo-first-order, Pseudo-second-order and intra particle diffusion models have been applied to the experimental data to predict the adsorption mechanism. The thermodynamics constants of the adsorption process, viz. ΔHo, ΔGo and ΔSo were evaluated. The results showed that the adsorption of nitrate and nitrite ions onto activated carbon was exothermic and non-spontaneous. The adsorption data followed second-order kinetics supporting that chemisorption process was involved. The obtained results show that ARSC can be used as an effective and natural low-cost adsorbent for the removal of nitrate and nitrite anions from wastewater.