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6195100 
Journal Article 
Oxidation of Formaldehyde Solutions Used for the Preservation of Reverse Osmosis Membranes: Phase II 
Boegli, WJ; Moody, CD; Murphy, AP; Rowley, LH 
1987 
This 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. The reaction was shown to be effective in oxidizing formaldehyde solutions, having initial concentrations of between 250 and 950 mg/L, to carbon dioxide and water. Following oxidation, residual formaldehyde levels measured < 2 mg/L (detection limit of the analytical method used) in the aqueous phase and < 0.4 mg/cu m in the carbon dioxide vapor phase. The oxidation was found to be rate controlled rather than mass diffusion controlled. 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. Parameter estimates and standard errors are presented for the oxidation of methanol (a preservative in the formaldehyde stock solution), formaldehyde, and formic acid, and for the decomposition of hydrogen peroxide. Conclusions are drawn relative to both the optimum pH range for the oxidation and the inhibiting/promoting effects of selected components in the reaction. (Author 's abstract) 
Water Resources Abstracts; Preservation; Water treatment; Reverse osmosis; Membrane processes; Formaldehyde; Oxidation; Chemical treatment; Formic acid; Ion exchange; Desalination; Catalysts; Membranes; Prototypes; Pilot plants; Carbon dioxide; Chemical reactions