Water contamination by nitrate and phosphate ions remains a critical environmental and public health challenge, largely driven by agricultural runoff and industrial activities. In this study, the adsorption capacity of nickel-doped calcium alginate beads (Ni-CaAlg) as a novel adsorbent for the dual removal of nitrate and phosphate ions from water has been investigated. Incorporating nickel ions into the alginate matrix enhanced adsorption capacity and provided additional active sites, fostering electrostatic interactions with the target contaminants. The characterization including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Energy-Dispersive X-ray Spectroscopy (EDX), Brunauer–Emmett–Teller (BET) analysis, and zeta potential measurement (pHpzc), confirmed the successful doping, structural integrity, and surface charge properties of the beads. Based on the findings, in the optimized conditions of pH 6, adsorbent dosage of 30 mg, and contact time of 120 min, the Ni-CaAlg beads had the highest adsorption capacities of 169.5 mg/g for nitrate and 238.1 mg/g for phosphate. The adsorption process followed a pseudo-second-order kinetic model and well-fitted with the Langmuir isotherm, confirming chemisorption and monolayer adsorption. The beads retained over 70 % of their initial adsorption capacity after ten adsorption-desorption cycles, underscoring their durability and reusability. These findings establish Ni-CaAlg beads as a promising and innovative solution for mitigating nitrate and phosphate contamination in water treatment systems.

中文翻译：

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使用掺镍海藻酸钙珠有效去除水中的硝酸盐和磷酸根离子


硝酸盐和磷酸根离子对水的污染仍然是一个关键的环境和公共卫生挑战，主要是由农业径流和工业活动驱动的。在本研究中，研究了镍掺杂海藻酸钙珠 （Ni-CaAlg） 作为一种新型吸附剂从水中双重去除硝酸盐和磷酸根离子的吸附能力。将镍离子掺入藻酸盐基质中可增强吸附能力并提供额外的活性位点，促进与目标污染物的静电相互作用。包括扫描电子显微镜 （SEM）、傅里叶变换红外光谱 （FTIR） 和能量色散 X 射线光谱 （EDX）、Brunauer-Emmett-Teller （BET） 分析和 zeta 电位测量 （pHpzc） 在内的表征证实了珠子的成功掺杂、结构完整性和表面电荷特性。结果表明，在 pH 6、吸附剂用量 30 mg、接触时间 120 min 的优化条件下，Ni-CaAlg 珠对硝酸盐的吸附容量最高，分别为 169.5 mg/g 和磷酸盐的 238.1 mg/g。吸附过程遵循准二级动力学模型，并与 Langmuir 等温线拟合良好，证实了化学吸附和单层吸附。经过 10 次吸附-解吸循环后，微珠仍保留了超过 70% 的初始吸附能力，强调了它们的耐用性和可重复使用性。这些发现将 Ni-CaAlg 珠确立为减轻水处理系统中硝酸盐和磷酸盐污染的一种有前途的创新解决方案。