Lead sorption by Togo rock phosphate as a sustainable solution to metal water depollution

The excessive use of chemical inputs in agriculture for wastewater irrigation, both on the surface and the groundwater. These pollutants are from the organic or inorganic origin. The treatment of these wastewaters is therefore very important and this is a great concern to many sustainable development goals such as preservation of human health, environmental protection and access to drinking water and sanitation. In Togo, no study has been carried out on the sorption capacity of rock phosphate. This work will lay emphasis on the lead chemical pollutant elimination by sorption on a mineral sorbent, the rock phosphate of Togo. The physicochemical characterization of the material by techniques such as X-ray diffraction, IR spectroscopy, pH of zero charge, Brunauer–Emmett–Teller surfaces was performed. The majority phase is fluoroapatite and traces of clay minerals have been found. Its specific surface is 20.78 m2 g–1 and its pHPZC = 6.82. The batch method was used for the sorption study. Several experimentation parameters having an impact on the sorption process of the pollutant such as the pH of the solution, time of contact, the amount of sorbent and the initial concentration of the pollutant have been studied. The results of our study show that the maximum sorption capacity of lead is 166.67 mg g–1 over the rock phosphate of Togo. The best sorption is obtained for pH values ≤ pHPZC. The equilibrium time is 30 min. In view of these different results, rock phosphate constitutes an alternative to commercial sorbent that costs a lot in the water treatment.