51313-02762-Synergistic and Divergent Effects of Surfactants on the Kinetics of Acid Dissolution of Calcium Carbonate Scale

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Product Number: 51313-02762-SG

ISBN: 02762 2013 CP

Author: Roxanne Shank

Publication Date: 2013

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Acid washing is a commonly employed method in the chemical cleaning of industrial equipment; however there are many factors to consider prior to adding acid to a given system. For example corrosion of the base materials that the equipment is made of must be avoided downtime of the system must be kept to a minimum and the economical factors (aka dollars and cents) of completing the job must be considered. None of these factors is separate from the other they all influence each other; therefore understanding the tricks and tools that can be employed in any chemical cleaning job is a necessity for maintaining the efficiency of the entire process. It is well understood that by raising the temperature of an acid solution the rate of dissolution of the scale is decreased; thus the reaction goes much faster. The addition of wetting agents which are designed to reduce the surface tension between the liquid chemical agent and the solid scale or deposit is also believed to decrease the rate of dissolution of the scale by allowing more of the chemical to reach the scale surface. However very little data exists regarding the actual rate constants contact angles and ultimately the efficiency of individual surfactant blends on the actual reaction rate with a given scale. A scale which is encountered frequently in chemical cleaning is limestone or calcium carbonate CaCO3. Using this common scale as a representative test sample for the efficiency of acid washing measurements of the rate constants for various commercially available wetting agents when added to acids commonly employed in industrial chemical cleaning applications are presented. Data presented here represents a variety of acids at a range of temperatures and acid molarities. Furthermore there exist four major types of wetting agents which can be classified as cationic anionic amphoteric and non-ionic; members from each of these groups are represented in this study and comparisons are drawn as to the efficiency of wetting of each type with respect to the observed rate of dissolution of the scale and the measured contact angles.