Submicrometric Iron Particles for the Removal of Pharmaceuticals from Water: Application to b-Lactam Antibiotics

Abstract

Sub-micrometric iron particles (Fe0) and amended Fe0(Cu0Fe0) were tested for the aqueous removal of b-lactam antibiotics. Comparative batch experiments were performed separately on aqueous solutions of dicloxacillin (DCX), cloxacillin (CLX) and oxacillin (OXA). Three different initial concentrations (1, 5 and 10 mg L-1) and four different iron loads (r = 10, 20, 40 and 53 g L-1) were tested. Furthermore, two different mixing regimes were tested: (i) non-disturbed conditions, and (ii) vortex mixing. This experimental design enabled the confirmation of the crucial role of in-situ formed iron corrosion products (Fe oxides) on the removal process. The dynamic process of Fe oxides formation induces adsorption and enmeshment (sequestration or co-precipitation) of dissolved antibiotics. Results clearly delineated the superiority of Cu0Fe0bimetallics compared to Fe0. For example, after 4 h of contact with iron particles at r = 40 g L-1, OXA, CLX and DCX (10 mg L-1each) disappeared to an extent of 31, 46 and 71%. However, quantitative antibiotic removal (~90%) was noticed when Cu0Fe0bimetallic was used at lesser load (r = 20 g L-1)under vortex mixing. On the other hand, non-disturbed systems showed partial removal (~ 25%) of antibiotics over 7 h of reaction at r = 10 g L-1(Fe0) while almost complete removals were noticed for the Cu0Fe0bimetallic system for the same metal load and period e.g. 75, 79 and 86% removal for OXA, CLX and DCX respectively.