Methods of removing phosphate from wastewater with a low phosphate concentration are of great environmental significance. In this study, immobilized beads were prepared by entrapping modified bentonite powder in calcium-alginate (Al-NaBT-CA), and the potential of the beads for phosphate removal from wastewater was investigated. The effects of pH (1-10) and initial phosphate concentration (0.5-50 mg/L) were also examined in batch experiments with Al-NaBT-CA beads. The optimum pH value for phosphate removal by Al-NaBT-CA beads was pH 3. In addition, a high initial phosphate concentration promoted phosphate adsorption. Adsorption kinetics showed that the adsorption of phosphate using beads followed a pseudo-second-order kinetic model (R2 = 0.98-0.99). The adsorption isotherm data was well fitted by the Sips adsorption model. The maximum phosphate adsorption capacity of the Al-NaBT-CA beads was 15.77 mg/g, which was slightly less than that of the modified powder. The specific surface area of the Al-NaBT-CA beads was 17.01 m2/g, and their average pore size was 13.41 nm. Scanning electron microscopy suggested that the high inner porosity and rough outer surface of the beads facilitated phosphate transfer.

中文翻译：

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通过钙藻酸盐微珠包裹的改性膨润土去除废水中的磷酸盐。

从低磷酸盐浓度的废水中除去磷酸盐的方法具有重大的环境意义。在这项研究中，通过将改性的膨润土粉末截留在藻酸钙（Al-NaBT-CA）中制备固定化的珠，并研究了从废水中去除磷酸盐的潜力。pH值（1-10）和初始磷酸盐浓度（0.5-50 mg / L）的影响还通过Al-NaBT-CA珠的分批实验进行了检验。通过Al-NaBT-CA珠去除磷酸盐的最佳pH值为pH3。此外，较高的初始磷酸盐浓度促进了磷酸盐的吸附。吸附动力学表明，珠粒对磷酸盐的吸附遵循伪二级动力学模型（R2 = 0.98-0.99）。Sips吸附模型很好地拟合了吸附等温线数据。Al-NaBT-CA珠的最大磷酸盐吸附能力为15.77 mg / g，略小于改性粉末。Al-NaBT-CA珠粒的比表面积为17.01m2 / g，并且其平均孔径为13.41nm。扫描电子显微镜表明，珠的高内部孔隙率和粗糙的外表面促进了磷酸盐的转移。