Enhancement of Polyacrylate Antiscalant Activity during Gypsum Deposit Formation with the Pretreatment of Aqueous Solutions with Spruce Wood Shavings

Considerable efforts are made worldwide to reduce inorganic scale in reverse osmosis plants, boilers and heat exchangers, evaporators, industrial water systems, geothermal power plants and oilfield applications. These include the development of new environmentally friendly antiscalants and the improvement of conventional ones. The present report is dedicated to the unconventional application of spruce wood shavings in combination with polyacrylate (PAA-F1) in a model case of gypsum scale formation. The electrical conductivity of freshly prepared gypsum solutions with a saturation SI = 2.3 and a concentration of 0.05 mol·dm(−3) was analyzed over time at 25°C. It is demonstrated that the small amounts of wood shavings (0.1% by mass) alone, after being in contact with CaCl(2) and Na(2)SO(4) stock solutions for 15 min, increase the induction time t(ind) by 25 min relative to the blank experiment (t(ind)(blank)). In the presence of PAA-F1 (0.1 mg·dm(−3)), the difference Δt(ind) = t(ind) − t(ind)(blank) constitutes 110 min, whereas the sequential treatment of the stock solutions with the shavings followed by PAA-F1 injection gives Δt(ind) = 205 min. The observed synergism is associated with the selective removal of colloidal Fe(OH)(3)(solid) and Al(OH)(3)(solid) nanoimpurities from the stock solutions via their sorption to the well-developed surface of wood. Wood shavings therefore represent a very promising and environmentally friendly material that can significantly improve the effectiveness of conventional antiscalants.