3-HYDROXYPROPIONIC ACID AS A CLEANING AGENT FOR SCALE REMOVAL
Publication Date: 2004-Mar-18
The IP.com Prior Art Database
Organic acids are often used in the formulation of cleanings products. Of particular interest for such applications is 3-hydroxypropionic acid, (3HP), which can be used as a cleaning agent to remove or dissolve scale comprising calcium carbonate, magnesium carbonate, calcium oxide, magnesium oxide, and silicates, or mixtures thereof.
Xiangsheng Meng, Ph.D. and Diza Braksmayer, Ph.D.
Industrial Bioproducts, Cargill, Incorporated
15407 McGinty Road West, MS# 69
Wayzata, MN 55391
Organic acids are often used in the formulation of cleanings products. Of particular interest for such applications is 3-hydroxypropionic acid, (3HP), which can be used as a cleaning agent to remove or dissolve scale comprising calcium carbonate, magnesium carbonate, calcium oxide, magnesium oxide, and silicates, or mixtures thereof. The concentration of 3-HP in the cleaning agent can range from 0.1% to 100% by weight.
Water contains calcium and magnesium carbonates, bicarbonates, and oxides, as well as silicates, as a result of contact with soil and rocky material. When this water is used at home and in industry, scale comprising carbonate, bicarbonate and oxides of Ca, Mg and other metals, as well as silicates, which can form an exceedingly hard scale, is formed on the surface of equipment on long contact, especially when water is heated. The most common industrial and domestic equipment/appliances are boilers, heat exchangers, cooling towers, membranes, compressors, coffee pots and teapots, bathtubs, toilet bowls, showers, and other water-using equipment. Removal of scale from equipment is critical for increasing efficiency and prolonging the lifetime of the equipment.
Figure 1 shows that 3HP has a greater capacity to maintain the solubility of mineral cations such as calcium relative to other organic acids.1, 2, 3
Figure 1. The solubility of the calcium salt of 3HP, actually higher than 100 grams per 100 grams of water, is significantly greater than the corresponding calcium salts of other organic acids.
Similar solubilities4 have been reported for 3HP salts of magnesium, zinc, iron,
A study was run where 2.7 cm x 2.7 cm x 1 cm blocks of Carrara marble, (CaCO3 marble, Stone Origins Inc., 301 Pleasant Drive, Dallas, TX), a model source of calcium carbonate scale, were submerged into 19 wt% aqueous solutions of 3HP, citric, glycolic and lactic acids for 24 hours at 25ºC. The blocks were weighed before submersion, after 15 minutes and 24 hours of soak to determine the weight loss.
It was observed that the marble weight loss in the first 15 minutes was higher for lactic and citric acids. This is probably due to the higher acidity of these acids (pKa is 3.86 for lactic acid and 3.13 for citric acid) relative to 3HP (pKa is 4.51)6. With time, 3HP continued to dissolve the marble block, whereas the other acids reached their calcium salt solubility limits and then precipitated and formed a hard re-sedimentation product.
The dissolution of the marble block in citric acid slowed down with time due to the precipitation of calcium citrate as a hard sediment onto the block, coating and preventing further dissolution of the block.
The marble block in lactic acid actually gained weight after 24 hours due to the re-s...