In seawater reverse osmosis, membrane scaling is one of the major issues affecting its widespread application in the desalination industry. In this paper, the effect of concentration of calcium and sulfate ions from 20 to 150 mM on calcium sulfate scaling of reverse osmosis (RO) and graphene oxide functionalized RO membranes was investigated. It was noted that the permeate flux declined more than 90% when the concentration of ions was increased to 50–150 mM. Principal component analysis was applied to the flux decline over time data, which helped to cluster the data sets based on the extent of membrane scaling at different conditions. The results of scanning electron microscopy showed that the morphology of crystals varied with the concentration from rod shaped to broad rosette structures. Furthermore, it was also found that the membrane surface was fully covered with precipitates, which resulted from both bulk and surface crystallization at higher concentrations of ions in feedwater. The results of X-ray diffraction confirmed that the precipitates formed on the membrane at different concentrations belong to gypsum (CaSO₄·2H₂O). The results of Fourier Transform Infrared spectroscopy helped to understand the interaction of gypsum with functional groups (–OH, –COOH, CH) of the membrane, which also varied at different concentrations. The contact angle analysis of the scaled membrane was also done to investigate the effect of scaling on the hydrophilicity of the membrane surface, thereby, affecting its inter/intra foulant interactions.

在海水反渗透中，膜结垢是影响其在海水淡化行业中广泛应用的主要问题之一。本文研究了20至150 mM的钙离子和硫酸根离子浓度对反渗透（RO）和氧化石墨烯官能化的RO膜硫酸钙结垢的影响。值得注意的是，当离子浓度增加到50–150 mM时，渗透通量下降超过90％。将主成分分析应用于流量随时间下降的数据，这有助于根据不同条件下膜结垢的程度对数据集进行聚类。扫描电子显微镜的结果表明，晶体的形态随浓度从棒状到宽玫瑰形结构而变化。此外，还发现，膜表面完全被沉淀物覆盖，这是由于进料水中离子浓度较高时的本体和表面结晶所致。X射线衍射结果证实，在膜上形成的不同浓度的沉淀物属于石膏（CaSO₄ ·2H ₂ O）。傅里叶变换红外光谱的结果有助于了解石膏与膜官能团（–OH，–COOH，CH ）的相互作用，该官能团在不同浓度下也会发生变化。还对结垢的膜进行了接触角分析，以研究结垢对膜表面亲水性的影响，从而影响其膜间/膜内污垢相互作用。