Nonsilicate Stabilization of Hydrogen Peroxide Bleach Solutions

Abstract

Alkaline solutions of hydrogen peroxide are stabilized by addition of calcium chloride and disodium phosphate. Evidence is given that stabilization may be due to the formation of CaHPO 4 as precipitate. THE stabiGty of highly purified hydrogen peroxide solutions is well established (4). There are a great many substances, however, that catalyze peroxide decomposition even when present in trace concentrations, particularly in alkaline solution. Since bleaching of cellulosic fabrics in mill practice is normally carried out in alkaline solution that may contain dissolved or suspended catalytic impurities, a stabilizing agent is added to prevent wasteful decomposition. Moreover, the uncontrolled release of oxygen from hydrogen peroxide is said to degrade cellulose chemically, so that an additional function of the stabilizer is to prevent this degradation by controlling the decomposition rate. A stabilizer may also serve to buffer the solution at the desired pH level and to provide detergent and penetrant action [4J., The most widely used stabilizer in textile plants is sodium silicate. Silicate has all of the aforementioned advantages, but associated with these are disadvantages that have often proved a source of trouble. The silicate apparently forms insoluble compounds with calcium and magnesium which deposit on the surface of equipment and fabric and are difbcult to remove. The result is that cloth is frequently abraded by the silicate deposits ; also, the presence of insoluble compounds on the cloth leads to difficulties in the dyehouse.Recently, Easton and Feldman [2] J reported the successful use of nonsilicate stabilized peroxide solutions. The' system which they used consisted of an alkaline peroxide solution containing calcium chloridge and disodium phosphate. The purpose of this paper is to present the results 41 experiments carried out in this laboratory that give some information about the stabilizing action of this system as well as the composition of the stabilizing agent.In most of the present work, the concentrations in solution of hydrogen peroxide, sodium hydroxide,. and calcium chloride were held constant and the siability of the peroxide determined as a function of concentration of disodium phosphate. A precipitate of calcium phosphate and/or calcium hydroxide was present in all of the solutions, the composition of the precipitate depending upon the amount of disodium phosphate present. In some of the experiments. the composition of the precipitate was determined by analyzing the filtrate and precipitate separately as a function of concentration of disodium phosphate. Experimental Solutions containing reagent grade hydrogen peroxide, sodium hydroxide, calcium chloride, and disodium phosphate were made up to a specified volume and maintained for 90 min. at 90° C. in a constant temperature bath. In most of the work the composition of the reaction solution was held constant except for the amount of Xa2H PO. that was added.Stock solutions of reagent grade Na,HPO,, 11~'aOH, and CaCl2 were made up, and t...