Novel bioadsorbents based on date pits for organophosphorus pesticide remediation from water

Abstract

The aim of the study was to examine the efficiency of date pits as an adsorbent to remove the organophosphate pesticide (profenofos) from water. A thermodynamic study was carried out to determine the homogeneity and spontaneous nature of the adsorbents. Three types of adsorbents, namely roasted date pits, activated date pits and nano-activated date pits were prepared from the date pits. Different physical and chemical characterizations were studied such as, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Brunauer-Emmett-Teller (BET) surface area, pore radius and pore volume. The surface area of the nano-activated date pit was the highest (485.4 m2/g). Moreover, the pore volume and pore radius were also the highest for the nano-activated date pits with values, 0.338 cm3/g and 17.8 Å, respectively. Therefore, nano-activated date pits have resulted in high removal percentage and removal capacity of profenofos from aqueous solution. Based on Langmuir adsorption isotherm model, the values of R2 was the highest for the nano-activated date pits. The adsorption maximum capacity (Qm) increased with temperature and was maximum for the nano-activated date pit following Langmuir adsorption isotherm model. Thermodynamic parameters showed a negative ΔGo for all three adsorbents and the values increased with temperature. The ΔHo value was positive for the three adsorbents and was the highest for roasted date pit (23.59 KJ/mol); resulting in an endothermic reaction. Whereas, the value of ΔSo was negative for the three adsorbents and was the highest for nano-activated date pits (-83.5 J/mol.K).