Abstract: Poly-γ-glutamic acid (γ-PGA) produced by fermentation of Bacillus sp was studied as a potential novel green scale inhibitor. The effects of γ-PGA concentration, molecular weight of γ-PGA, temperature, pH and Ca2+concentration on the scale inhibiting rate of γ-PGA were respectively analyzed using static anti-scaling method, and the structural characterization of scale inhibiting products and possible mechanism were investigated. The results reveal that both large molecular γ-PGA and small molecular γ-PGA have inhibiting efficiency. More specifically, small molecular γPGA shows the better inhibiting efficiency with their lowest concentration to get 100% inhibiting efficiency from scale of CaSO4 and CaCO3 being 4 mg/L and 2 mg/L respectively, while large molecular γ-PGA to get the same efficiency in the same condition is 20 mg/L respectively.

Key words: scale inhibitor, scale inhibiting behavior, poly-γ-glutamic acid(γ-PGA), scale inhibitor, scale inhibiting behavior