Commercial bentonite clay as low-cost and recyclable "natural" adsorbent for the Carbendazim removal/recover from water: Overview on the adsorption process and preliminary photodegradation considerations

This paper reports the use of commercial bentonite clay as cheap natural adsorbent for the Carbendazim removal from water. The very fast and quite complete removal (80 % of the pollutant) occurred in 15 min by using 1 g of adsorbent, with a bentonite adsorption capacity of 1.5 mg/g. Around 100 % of the Carbendazim removal can be reached extending the contact time to 60 min. Regarding the sustainability of the process, the recovery of both the emerging pollutant and adsorbent were successfully obtained, lowering the associated costs for a possible industrial scaling up. Indeed, several cycles of adsorption and desorption, in ethanol, on the same adsorbent were performed. The evaluation of various parameters affecting the adsorption process, such as the amount of the pollutant and clay, the pH, temperature, and the effect of salts in solutions, was considered. The adsorption process followed the pseudo-second order kinetic model and the Freundlich and Temkin adsorption isotherms well fitted the experimental data suggesting the heterogeneous character of the Carbendazim physical and chemical sorption on the clay. Preliminary in flux experiments were also presented and by using 2 g of adsorbent, the 100 % removal of the pollutant occurred in 2 s.