Ettringite is a hydrous calcium aluminum sulfate mineral present in cement. In this study, ettringite was synthesized via co-precipitation to remove methyl blue, dichromate, and copper ions from solutions with various pH values. The synthesized ettringite was characterized using scanning electron microscopy, X-ray photoelectron spectrometry, Fourier transform infrared spectroscopy, zeta potential analysis, and the Brunauer–Emmett–Teller method. Equilibrium adsorption experiments were performed using methyl blue and dichromate at pH values ranging from 5 to 11. To avoid precipitation, equilibrium adsorption experiments were performed on copper ions in solutions with pH values of 3, 4, and 5. The adsorption kinetics experiments for each contaminant were performed at pH 5. The results showed that ettringite was successfully synthesized, and calcite might have precipitated during the synthesis process. The point of zero charge was at pH 8.6. The maximum adsorption capacities for methyl blue, dichromate, and copper ions at pH 5 were 406, 321, and 365 mg/g, respectively. The adsorption kinetics fitted the pseudo-second-order model well. The properties of the contaminants affect their equilibrium and rate constants. Ion exchange is regarded as the primary adsorption mechanism, whereas the other mechanisms include complexation, hydrogen bonding, surface precipitation, π-interaction, and van der Waals forces. This study revealed a new adsorbent, ettringite, for the removal of contaminants from wastewater, which is a promising alternative adsorbent that can be used under specific conditions.

钙矾石是一种存在于水泥中的水合硫酸钙铝矿物。在本研究中，通过共沉淀合成钙矾石，以去除不同 pH 值溶液中的甲基蓝、重铬酸盐和铜离子。使用扫描电子显微镜、X 射线光电子能谱、傅里叶变换红外光谱、zeta 电位分析和 Brunauer-Emmett-Teller 方法对合成的钙矾石进行了表征。使用甲基蓝和重铬酸盐在pH值5~11范围内进行平衡吸附实验。为了避免沉淀，对铜离子在pH值3、4、5的溶液中进行平衡吸附实验。各吸附动力学实验在pH 5下进行污染分析。结果表明钙矾石成功合成，方解石可能在合成过程中沉淀。零电荷点为 pH 8.6。 pH 5 时对甲基蓝、重铬酸盐和铜离子的最大吸附容量分别为406、321 和365 mg/g。吸附动力学很好地拟合了准二阶模型。污染物的性质影响其平衡常数和速率常数。离子交换被认为是主要的吸附机制，而其他机制包括络合、氢键、表面沉淀、π相互作用和范德华力。这项研究揭示了一种新的吸附剂钙矾石，用于去除废水中的污染物，这是一种有前途的替代吸附剂，可以在特定条件下使用。