Abstract Scale deposition is considered as one of the most critical problems leading to permeate flux decline and deterioration of membrane surface in reverse osmosis (RO) desalination plants. This study aims to preparation of novel high effective scale inhibitor, chitosan biguanidine hydrochloride (CG), to inhibit the precipitation of calcium sulfate and carbonate onto the membrane surface. The modification of Chitosan by the guanidine group was to enhance its solubility in water, because chitosan as it is dissolves only in moderately acidic solutions. CG was synthesized and characterized by FTIR, 13C NMR and 1H NMR. The inhibition efficiency of our antiscalant was evaluated against CaSO4 and CaCO3 solutions at both static (induction time) and real application tests (cross-flow unit for 6 h). CG showed a good performance as scale inhibitor for CaSO4 and CaCO3 at about 10 and 15 mg·L−1 with flux decline of 2.6 and 5% in feed water, respectively. In addition, the induction time of precipitation of CaSO4 increased from 3 to 15 min with the addition of CG. SEM analysis at different magnifications for Cs and CG proved that CG strongly affects the morphology of the precipitated calcium sulfate and calcium carbonate leading to distortion of crystals.

中文翻译：

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新型膜脱盐阻垢剂壳聚糖双胍盐酸盐的制备、表征与评价

摘要 水垢沉积被认为是导致反渗透（RO）海水淡化厂产水通量下降和膜表面劣化的最关键问题之一。本研究旨在制备新型高效阻垢剂壳聚糖双胍盐酸盐（CG），以抑制硫酸钙和碳酸盐在膜表面的沉淀。胍基对壳聚糖的修饰是为了提高其在水中的溶解度，因为壳聚糖仅在中等酸性溶液中溶解。CG合成并通过FTIR、13C NMR和1H NMR表征。我们的阻垢剂在静态（诱导时间）和实际应用测试（错流装置 6 小时）中对 CaSO4 和 CaCO3 溶液的抑制效率进行了评估。CG 作为 CaSO4 和 CaCO3 的阻垢剂表现出良好的性能，在 10 和 15 mg·L-1 左右，进水中的通量下降分别为 2.6% 和 5%。此外，随着CG的加入，CaSO4沉淀的诱导时间从3分钟增加到15分钟。Cs 和 CG 在不同放大倍数下的 SEM 分析证明，CG 强烈影响沉淀的硫酸钙和碳酸钙的形态，导致晶体变形。