Removal of ibuprofen by sodium alginate-coated iron-carbon granules combined with the ultrasound and Fenton technologies: influencing factors and degradation intermediates.

This study focuses on the preparation of sodium alginate-coated iron-carbon granules (FeCGs) and their capacity to remove ibuprofen (IBU) by combining Fenton and ultrasound technologies. The preferred preparation conditions are as follows: 2% (w/v) sodium alginate, 10% (w/v) iron fillings and biochar, and used CaCl2 as the cross-linking agent. 74.72% of IBU was removed by ultrasound/FeCG under 10 g/L FeCG and 250 W ultrasound power. Fenton/FeCG could remove 92.41% of IBU under 10 g/L FeCG and 2 mM H2O2. Under the above experimental conditions, ultrasound/FeCG has higher reaction speed (9.44 × 10-3 min-1) than Fenton/FeCG (4.95 × 10-3 min-1). However, Fenton/FeCG could remove more TOC than ultrasound/FeCG. During the reaction using the Fenton/FeCG system, 11 degradation intermediates were detected, but only 7 intermediates were produced by the ultrasound/FeCG system. A common single-chain product C5H10O3 formed by IBU degradation was detected in the reaction products during Fenton/FeCG reaction, which benzene ring structure was destroyed; however, the minimum molecular weight of the product detected using the ultrasound/FeCG system was that of C8H10O; the benzene ring structure of IBU is not destroyed. This study provides guidance in the preparation of sodium alginate-coated FeCGs, evaluating the applicability of Fenton/FeCG and ultrasound/FeCG, which was meaningful for organic pollution wastewater treatment.