The peanut shell treated with 1-Chloro-2,3-epoxypropane and its application as an adsorbent in the removal of nitrate from water

Nitrate removal from aqueous solutions was studied using the modified peanut shell in batch experiments. The peanut shell was modified by 1-Chloro-2,3-epoxypropane in the presence of pyridine as an organic catalyst. The removal of nitrate ions was studied by changing experimental conditions such as the amount of sorbent, contact time, concentration, and temperature. It was observed that more than 90% of nitrate ions were removed in less than 15 min from the aqueous solution at 10 degrees C. The Langmuir isotherm was found to best fit the adsorption data with high measures of the correlation coefficients (r(2) > 0.99). Plus, the maximum adsorption capacity of 86.2 mg/g at 10 degrees C was calculated. The adsorption mechanism of nitrate was in a good agreement with the pseudo-second-order kinetic model. FTIR and SEM analysis were conducted to reveal the structural and morphological properties of the sorbent and it was indicated that the sorption mechanism is physical and also the modified peanut shell has possibly good surface characteristics to be employed as a low-cost sorbent. In the case of desorption, to study reusability of the sorbent, 6 runs of recycling experiments were carried out and the adsorption and desorption capacities remained nearly the same. The thermodynamic properties such as Delta G(ads) and Delta S-ads were also calculated and revealed the spontaneous nature of the process, besides an enthalpy calculation showed that the adsorption process is probably physisorption and decreasing temperature helps the procedure.