Elimination of sulfates from wastewaters by natural aluminosilicate modified with uric acid

Natural aluminosilicate activated by a heat/acid treatment, followed by modification with uric acid was used to remove sulfates for treatment of wastewater effluent. Natural aluminosilicates were studied in every stage of the modification (namely activation, modification with uric acid, and after sulfates absorption) by scanning electron microscopy (SEM), spectroscopy X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), surface area (BET), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Z potential. More than 60% of the initial concentration of sulfates (500 mg/l) was removed with the natural aluminosilicate modified with uric acid. Absorption isotherms rendered a mechanism with contributions from both Langmuir and Freundlich mechanisms. This study opens the path for the use of natural and abundant local material to remove sulfates using a modifier already present in wastewater effluents as contaminant.