“Green” scale inhibitors in water treatment processes: the case of silica scale inhibition

Abstract

A B S T R A C TThis paper focuses on scale control approaches using a number of "green" silica scale inhibitors. These findings may be of interest to chemists and engineers in the fields of cooling and boiler water, pulp and paper, detergents, oil, gas, etc. In light of increasing environmental concerns, this research acquires significant interest. Also, in this paper, the effects of biological and synthetic polymers on the formation of amorphous silica are discussed. The importance of synergies between polyelectrolytes on silica inhibition is also discussed. A specific example of a zwitterionic polymer phosphonomethylated chitosan (PCH) is further analyzed for its inhibitory activity. Specifically, the ability of PCH to retard silicic acid condensation at circumneutral pH in aqueous supersaturated solutions is explored. Furthermore, the effects of either purely cationic (polyethyleneimine, PEI) or purely anionic (carboxymethylinulin) polyelectrolytes on the inhibitory activity of PCH are systematically studied. It was found that the action of inhibitor blends is not cumulative. PCH/PEI blends stabilize the same level of silicic acid as PCH alone in both short-term (8 h) and long-term (72 h) experiments. Lastly, six polyethylene glycol polymers are used as silica scale inhibitors. Their Molecular Weights range from 1,550 to 20,000. There is a profound dependence of inhibitory performance on the additive Molecular Weight. However, this dependence seems to be less significant for Molecular Weights > 10,000. Mechanistic implications will be discussed as well.

Silicic acid condensation under the influence of water-soluble polymers: from biology to new materials

“…131,137,173,174 For instance, inhibition of Si(OH) 4 condensation is observed for a wide range of polymeric cations and amines. The reason for this contradiction is possibly due to the different procedures employed for measurement of monomeric silicic acid concentration.…”

“…The addition of various polymers capable of interacting with PSA prevents the precipitation. 131,134,[192][193][194] The soluble composite nanoparticles could be considered as new biomimetic precursors for the synthesis of more complex siliceous structures. These nanoparticles bear negative or positive charge depending on the nature of the organic polymer and can interact with oppositely charged objects.…”

“…Interaction between growing PSA nanoparticles and macromolecular chains oen results in stable soluble nanoparticles 63,64,85,[90][91][92][93]95,96,115,116,120,131,132 or in a product consisting of uniform spherical composite particles. 24,61,62,[65][66][67][68][69][70][71][75][76][77]98,99,[106][107][108]111,112,114,117,121,124,134,135,137,139,143,149,153,155,157 These variants exist in the case of relatively low silicon content in the system, when all PSA nanoparticles can nd chains of organic polymer.…”

DLS study of a phosphonate induced gypsum scale inhibition mechanism using indifferent nanodispersions as the standards for light scattering intensity comparison

“…A widely used technique for controlling scale deposition is an application of chemical inhibitors [2,[5][6][7][8]. Commonly used commercial antiscalants are represented mostly by three chemical families: polyphosphates, organophosphonates and organic polyelectrolytes (polyacrylates (PA), and polycarboxysulfonates (PCS)).…”

Study of Polyaspartic Acid and Chitosan Complex Corrosion Inhibition and Mechanisms

“…Chitosan (CS) is a natural biodegradable biopolymer that is currently the only natural alkaline sugar polymer found in nature, and is an environmentally friendly and renewable resource. However, the inhibition of chitosan has been rarely reported [13][14]. Therefore, it is imperative to conduct further studies on the scale inhibition and corrosion inhibition properties of chitosan and its derivatives.…”