Abstract

Phosphorous is one of the essential elements for living-forms on the Earth; however, the excessive presence of phosphate in the environment causes water pollution. Several methods have been developed and applied for phosphate removal in wastewater and adsorption is considered as a low-cost, simple, and stable technology for wastewater with low phosphate concentration. Although several mesoporous materials have been used as adsorbents, there has not been any report on the utilization of rice husk ash as support for iron oxide/hydroxide growth toward phosphate removal. In this study, flower-like iron(III) oxide/hydroxide on activated rice husk ash support (Fe-ARHA) was synthesized and applied as a novel material for phosphate removal in aqueous solution. ARHA was prepared by the chemical corrosion method with HF acid using bottom ash of a brick kiln using rice husk as fuel. Flower-like iron oxide/hydroxide was then grown on the surface of ARHA by precipitation of iron(III) sulfate using urea solution. The materials were then characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy to explore their properties. The mechanism for the formation and growth of flower-like iron oxide/hydroxide on the ARHA surface was proposed. In batch phosphate removal test, Fe-ARHA with Fe/ARHA ratio of 5 : 3 showed the highest adsorption capacity of 37.8 mg/g, which could be due to the interaction between iron oxide/hydroxide and ARHA support. This flower-like morphology and the interaction let more iron oxide/hydroxide surface be exposed to the water environment and effectively serve as adsorption sites for phosphate removal. These results prove the potential for the utilization of waste rice husk ash and iron oxide for water and advanced wastewater treatment applications.

中文翻译：

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稻壳灰载体上花状氧化铁/氢氧化物的合成及其在水中除磷的应用

摘要

磷是地球上生命形式的基本元素之一；然而，环境中磷酸盐的过量存在会导致水污染。已经开发并应用了几种去除废水中磷酸盐的方法，吸附被认为是一种低成本、简单、稳定的低磷酸盐废水处理技术。尽管几种介孔材料已被用作吸附剂，但还没有任何关于利用稻壳灰作为支持氧化铁/氢氧化物生长以去除磷酸盐的报道。在这项研究中，合成了活性稻壳灰载体上的花状氧化铁（III）/氢氧化物（Fe-ARHA），并将其用作一种在水溶液中去除磷酸盐的新型材料。以稻壳为燃料，以砖窑的底灰为原料，通过HF酸化学腐蚀法制备ARHA。然后通过使用尿素溶液沉淀硫酸铁（III），在 ARHA 表面上生长花状氧化铁/氢氧化物。然后通过扫描电子显微镜、能量色散 X 射线光谱、X 射线衍射和傅里叶变换红外光谱对材料进行表征，以探索它们的性质。提出了在 ARHA 表面形成和生长花状氧化铁/氢氧化物的机制。在批量除磷试验中，Fe/ARHA 比为 5:3 的 Fe-ARHA 显示出最高的吸附容量 37.8 mg/g，这可能是由于氧化铁/氢氧化物与 ARHA 载体之间的相互作用。这种花状形态和相互作用使更多的氧化铁/氢氧化物表面暴露在水环境中，并有效地作为去除磷酸盐的吸附位点。这些结果证明了利用废稻壳灰和氧化铁进行水和高级废水处理应用的潜力。