USE OF COMPLETELY MIXED FLOW-THROUGH SYSTEMS - HYDROLYSIS OF PHENYL PICOLINATE

Experimental equipment was developed to study the hydrolysis of enviro nmentally relevant compounds in completely mixed flow-through reactors . The hydrolysis of a carboxylic acid ester, phenyl picolinate (PhP), was investigated in homogeneous solutions and in the presence of titan ium dioxide particles. In the absence of solids, the hydrolysis of PhP is dominated by the acid-catalyzed reaction below pH 4 and by the bas e-catalyzed reaction above pH 5, while the neutral hydrolysis is of mi nor importance across the whole pH range investigated (2 < pH < 8). Ho wever, in presence of 10 g of TiO2 L-1 (similar or equal to 420 m(2) s urface area L-1), the neutral, surface-catalyzed reaction dominated th e overall hydrolysis process in the entire range from pH 2 to pH 9. St eady-state rates of the heterogeneous hydrolysis were about 1 order of magnitude slower in completely mixed flow-through systems than initia l hydrolysis rates in batch systems. This was attributed to reaction p roducts occupying reactive sites at the mineral surface, thus hinderin g the adsorption of the educt PhP.