Pillared bentonite from Al-Fe-Cu polymeric precursor in solid state for the catalytic oxidation of amoxicillin

A Colombian bentonite is successfully pillared with Al, Al-Fe, Al-Cu and Al-Fe-Cu polyhydroxications in solid state. The effect of the Fe and Cu content on the physicochemical properties of the pillared bentonite was evaluated using characterization techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD) and textural analysis (nitrogen physisorption). The Box-Behnken statistical experiment design was used to determine the optimal parameters of the independent variables hydrogen peroxide (0.120–0.144 M), catalyst load (0.5–1.5 g/L) and type of catalyst (PILC FeCu1, FeCu5, FeCu10) in the catalytic oxidation (CWPO) of amoxicillin. The optimized conditions of hydrogen peroxide (0.137 M) and catalyst loading (0.7 g/L) were used to compare the catalytic performance of the catalysts with 1%, 5% and 10% Al-Fe, Al-Cu and Al-Fe-Cu reaching a removal between 91% and 100% of amoxicillin at T and ambient pressure. The rate constants determined allowed the identification of the best catalyst of each series to study the degree of mineralization and choose the best catalyst: the pillared clay with AlFeCu10, with a TOC removal of 24.6% after 2 h of reaction. After three cycles of reuse, the catalyst maintained its catalytic activity in removing amoxicillin without leaching any metal.