Materials Performance

DEC 2014

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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52 DECEMBER 2014 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 53, NO. 12 CHEMICAL TREATMENT D The infuence of iron oxide (Fe 2 O 3 ) on the performance of calcium carbon- ate (CaCO 3 ) inhibitors was investi- gated. Results show that a small amount (10 to 100 mg) of Fe 2 O 3 added to the CaCO 3 supersaturated solution exhibited marked antagonistic effects on inhibitor performance. Part 1 (No- vember 2014 MP) of this article de- scribed the experimental work. Part 2 covers the effects of Fe 2 O 3 on the in- hibitors. Deposition of various mineral scales on heat exchangers and reverse osmosis (RO) membranes is a major problem in water t r e a t m e n t f o r b o i l e r s , d e s a l i n a t i o n , geothermal, and oil production. Mineral scales are commonly carbonate, sulfate, phosphate, and f luoride salts of alkaline earth m etal s. Th e problem of calcium c a r b o n a t e ( C a C O 3 ) s c a l e i s m o r e pronounced at ele vat ed t emp eratures, since the solubility of scaling salt decreases with temperature. Also, scaling is often accompanied by corrosion that causes d a m a g e t o m e t a l s . Fre q u e n t ly, s c a l e removal leads to discontinuous operation of the systems. 1 Influence of Iron Oxide on Polymer Performance Feed water used in many industrial pro cesses comes from various sources, such as rivers, ponds, and lakes, and contains a variety of soluble and insoluble impurities (suspended particles). Typical suspended particles include metal oxides/hydroxides, clay, silt, metal carbonates, algae, bacteria, and viruses. It is generally known that higher concentrations of suspended parti cles not only lead to high turbidity, but also provide high surface area for adsorption of dissolved species including tannins, fulvic acid, humic acid, and additives used to control scale formations. Effect of Mixing Time To understand the influence of mixing time after the addition of iron oxide (Fe 2 O 3 ) to the CaCO 3 supersaturated solutions, a number of precipitation experiments were done in the presence of 5.0 mg/L of HP1 [poly(acr ylic acid)] and 50 mg of Fe 2 O 3 . Results presented in Figure 1 show that mixing time exhibits a marked negative e f f e c t o n t h e p e r f o r m a n c e o f H P 1 . Inhibition values (%I) obtained at 24 h after mixing for 0.0 min, 0.50 and 1.0 min are 59, 48, and 45%, respectively, compared to 88% obtained at 24 h in the absence of Fe 2 O 3 . Increasing the mixing time three fold ( from 1 to 3 min) did not show any significant impact (45 to 42%) on the performance of HP1, suggesting that mixing time plays an important role in the adsorption of HP1 on Fe 2 O 3 particles or removal of HP1 from the CaCO 3 supersaturated solution. Impact of Iron Oxide on Calcium Carbonate Inhibitors— Part 2 Zahid amjad and jeremy Penn, Walsh University, North Canton, Ohio

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