Additive-Driven Dissolution Enhancement of Colloidal Silica. 1. Basic Principles and Relevance to Water Treatment

Abstract

The effect of various chemical additives (small molecules and polymers) on the dissolution of two kinds of colloidal silica (Aerosil 200 and laboratory-synthesized, SSD) is systematically studied at pH 10. The silica scale dissolvers tested are 5-carboxybenzotriazole (CBZT), amino-tris(methylene phosphonic acid) (AMP), a phosphino-polycarboxylic acid (PPCA), diethylenetriamine pentacarboxylic acid (DETPA), a proprietary polymer (Genesol 40), poly(acrylic acid) (PAA), ethylenediamine-tetrakis(methylenephosphonic acid) (EDTMP), phosphonobutane-1,2,4-tricarboxylic acid (PBTC), sodium metaborate, and N-phosphonomethylimino-diacetic acid (PMIDA). Of the polymeric additives only Genesol 40 shows some dissolution activity, dissolving ∼280 ppm silica at 10 000 ppm dosage after 72 h. PBTC and DETPA are the best-performing additives of all those tested. PBTC is effective even at the 2500 ppm dosage, as it solubilizes ∼290 ppm silica after 72 h. Its efficiency is dosage-dependent. DETPA is also an effective silica dissolver. Its behavior is similar to that of PBTC. Its best dosage is 7500 ppm, which yields dissolution of 322 ppm silica (after 24 h), 340 ppm (after 48 h), and 333 ppm (after 72 h). SSD silica is a very recalcitrant deposit showing resistance to dissolution even by the most effective additives, PBTC and DETPA.

Unexpected “Hammerlike Liquid” to Pulverize Silica Powders to Stable Sols and Its Application in the Preparation of Sub-10 nm SiO2 Hybrid Nanoparticles with Chirality

“…4−6 Small organic carboxylic acids in their deprotonated state are also used for the dissolution of SiO 2 at room temperature but with a long time (1–7 days). 7,8 Unfortunately, in this research with carboxylic acids, not much information was available on the sizes and compositions of the final products after dissolution processing. Sugar, together with organic amine catalysts, was reported to digest the SiO 2 gel or silicate minerals to reduce their sizes down to 200–450 nm under ambient pressure and mild heating (60–100 °C).…”

Effects of Additives and Metals on Crystallization of Nano-Sized HZSM-5 Zeolite for Glycerol Aromatization

“…In addition, Na + could also play a role of cation template similar as TPA + , which would accelerate the nucleation and lead a smaller crystal. CMC-Na and SA contributed a polymer hydrogel system, which allowed ZSM-5 crystallized in a three-dimensional network of the cross-linked structure to obtain small crystals [28,30,31]. However, the crystalline size had little change and even increased with the addition of PEG-10000 (HZSM-5-P) and KH-560 (HZSM-5-K).…”

Preparation, characterization, and Ce(III) adsorption performance of poly(allylamine)/silica composite

“…(2014) [1][2][3][4][5][6][7][8][9][10][11][12][13][14] www.deswater.com doi: 10.1080/19443994.2014.944221 from further solvent extraction stages [5]. Ion exchange using polymeric resins and solvent extraction has become the most useful procedure for extraction and separation of REEs.…”

“…Noticeably, silica can effectively overcome the drawback of resin in mechanical strength [7,8]. Nevertheless, the adsorption capacity of pure silica is generally low because of the evident lack of adsorption sites on its surface.…”