Abstract
Abstract To remove silicic acid from aqueous solutions, a novel gallic acid-type resin (GA-type resin) was prepared by a grafting method. The effects of the adsorption capacity, pH and presence of NaCl, NaNO3, Na2SO4, and NaCO3 salts on the silicic acid removal were studied. The GA-type resin adsorbs monosilicic acid, silicate ions, and polymeric silicic acid. The adsorption capacity of 4.64–4.94 mg/g was achieved in a short adsorption time (Qm of 8.99 mg/g) and is 30–40 times larger than that of the OH-type resin. The silicic acid removal efficiency was almost unaffected by the pH and common anions when the common anion and silicic acid contents were similar, proving the GA-type resin exhibits an excellent performance for selective adsorption of silicic acid. The Temkin isotherm model can well describe the adsorption process, which is chemical adsorption, and indicates that the adsorption heat decreases with the increasing adsorption amount. The adsorption mechanism of silicic acid on the GA-type resin involves dehydration condensation reactions of the hydroxyl groups in silicic acid and gallic acid. The GA-type resin can be efficiently regenerated and reused after treatment with an HCl solution.
Highlights
Mineral scale formation in pipelines, wells, heat exchangers, and membranes is one of the main problems that hinders the wide utilization of water resource regeneration and seawater and brackish water desalination (Semiat et al ; Zarrouk et al ; Menzri et al )
For all the pH values, the amount of silicic acid adsorbed by the GA-type resin was 4.64–4.94 mg/g, which was 30 times greater than the amount adsorbed by the OH-type resin (0.14–0.35 mg/g) and indicated that the GA-type resin has potential application value for silicic acid removal from water over a wide pH range
A new, selective silicic acid removal resin was prepared by a grafting method, and the resin showed good adsorption properties for silicic acid from aqueous solutions with a wide pH range
Summary
Mineral scale formation in pipelines, wells, heat exchangers, and membranes is one of the main problems that hinders the wide utilization of water resource regeneration and seawater and brackish water desalination (Semiat et al ; Zarrouk et al ; Menzri et al ). Silica scale formation in many industrial processes can significantly shorten the lifetime of the water treatment equipment, increase the maintenance costs and energy consumption of an operation due to water flow or membrane blockages, and cause equipment corrosion, unscheduled shutdown time and system efficiency loss Two distinct approaches are used to control silica scaling: (a) addition of scale
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