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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55 NACE INTERNATIONAL: VOL. 53, NO. 12 MATERIALS PERFORMANCE DECEMBER 2014 Impact of Iron Oxide on Calcium Carbonate Inhibitors—Part 2 possible that amorphous CaCO 3 (ACC) or vaterite cr ystal phases were stabilized , which yielded irregular shapes. XRD analy- sis showed the presence of calcite (104) and vat erit e (110). Th e absence of al l ref lections again may be due to the pre- ferred orientation of the crystallites on the filter paper. No aragonite formation was observed. The effect of Fe 2 O 3 in the presence of HP1 was also investigated . Figure 6(d) shows that CaCO 3 crystals are covered by nanoparticles of Fe 2 O 3 . Proposed Mechanism(s) for Performance Loss of Polymers by Fe 2 O 3 The antagonistic effect of Fe 2 O 3 on vari- ous polymeric additives may be attributed to one or more of the following: a) E f f e c t of Fe ( I I I ) : He r z o g , e t a l . reported the presence of low concen- trations (0.06 mg/L) of Fe(II) and Fe(III) exhibit an inhibitory effect on CaCO 3 precipitation from supersatu- rated solutions. 11 In experim ents involving Fe 2 O 3 , the Fe(III) concen- tration in the filtrate at 24 h was ~0.02 mg/L. To check any synergistic or antagonistic effect on the perfor- mance of additives, CaCO 3 precipita- tion experiments were done. Results show that Fe(III) under the condi- tions employed did not exhibit any significant inf luence on the perfor- mance of HP1. b) Interactions of Fe(III) with anionic inhibitors: The formation of insolu- b l e s a l t s of – C O O H c o n t a i n i n g polymers with metal ions such as Ca, Mg, Ba, etc., has been reported. 12 It is possible that trace levels of Fe(III) may form an insoluble salt with anionic polymers, thus reducing the polymer concentration in solution. c) Removal of additives via adsorption on Fe 2 O 3 : The influence of homo-, co-, and terpolymers as dispersants for suspended matter has been investi- gated . 7 Results reveal that acr ylic acid- and maleic acid-based homo- and copolymers disperse suspended FIGURE 5 Effect of Fe 2 O 3 (50 mg) on the performance of homo-, co-, and terpolymers (2.5 mg/L). FIGURE 6 SEM micrographs of CaCO 3 crystals grown (a) in the absence of HP1 and Fe 2 O 3 ; (b) in the presence of Fe 2 O 3 ; (c) in the presence of 2.5 mg/L HP1; and (d) in the presence of 2.5 mg/L of HP1 and 50 mg Fe 2 O 3 .

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