Oxidation of Formaldehyde Solutions Used for the Preservation of Reverse Osmosis Membranes: Phase 2

摘要

The report presents the results of the second phase of a two-phase study of a new process for the catalytic oxidation, at ambient temperatures, of dilute formaldehyde used in aqueous solutions for the preservation of cellulose acetate reverse osmosis membranes. The oxidation, involving hydrogen peroxide and an iron (ferric chloride) catalyst, was previously tested in a bench-scale adiabatic reactor to develop test data showing the effect of selected variables (temperature, reactant and catalyst concentrations, and stirring rate) on the oxidation of formaldehyde and formic acid, an intermediate oxidation product. In the present work, additional adiabatic tests were conducted at a pilot-scale (solution volume 426 times greater than bench-scale) to verify the assumption of direct scale-up for the reactor. In addition, the effects of background salinity, mixing power input, and method of hydrogen peroxide addition to the reactor (metered versus batch addition) were investigated. An empirical reaction-rate model was developed from a series of isothermal bench-scale tests to predict and optimize the reaction.