Highly efficient removal of uranium(VI) from aqueous solution using poly(cyclotriphosphazene- co -polyethyleneimine) mic
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Highly efficient removal of uranium(VI) from aqueous solution using poly(cyclotriphosphazene‑co‑polyethyleneimine) microspheres Xiaoqing Xie1 · Yanfei Wang1 · Zeng Xiong1 · Hongzheng Li1 · Chen Yao1 Received: 19 July 2020 / Accepted: 7 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Poly(cyclotriphosphazene-co-polyethyleneimine) microspheres with the solid structure were synthesized by precipitation polymerization method for the separation of highly toxic uranium(VI). The structure and morphology of the prepared microspheres were analyzed via FTIR, SEM–EDS, TEM and BET. The optimal adsorption conditions were also investigated, and the maximum adsorption capacity was 274.2 mg g−1. The experimental results showed that the adsorption kinetics conformed to the pseudo-second-order kinetics and was in good agreement with the Langmuir adsorption isotherm model. Removal of uranium(VI) ions was achieved by the complexation between the amino groups on the adsorbent and uranyl ions. Keywords Poly(cyclotriphosphazene-co-polyethyleneimine) · Microspheres · Uranium(VI) · Adsorption
Introduction With the development of urbanization and industrialization, people’s demand for energy is also increasing [1, 2]. People’s daily energy consumption is mainly fossil fuels such as petroleum, coal and natural. Due to the rapid consumption of these fossil fuels, they are not only on the verge of exhaustion, but also cause environmental pollution [3]. Therefore, clean energy has attracted people’s attention because of its renewability and no emission of toxic gases. Nuclear electricity generation is a sustainable energy source, which plays an increasingly important role in meeting people’s growing energy needs [4, 5]. Nevertheless, in the process of mining and utilizing of nuclear energy, a variety of heavy metalcontaining waste streams are produced, flowing into groundwater and the ocean, which can cause long-term harm to human health and the natural environment [6–8]. Uranium is a crucial nuclear fuel with high radioactively and chemical toxicity [9]. When trace amounts of uranium are slowly accumulated in humans and animals, they can cause chronic poisoning and genetic mutations. WHO uses 9 μg L−1 as the maximum value for uranium(VI) pollutants, and U.S. EPA has set the maximum concentration level of uranium(VI) in * Yanfei Wang [email protected] 1
School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China
drinking water at 30 μg L−1 [10]. Hence, the treatment of various uranium-containing wastewater is of great significance for the protection of human health and the ecological environment. In the natural environment, uranium usually exists in four chemical valence forms (U(III), U(IV), U(V), U(VI)), among which U(VI) mainly exists in water [11]. In general, the form of uranium(VI) in water depends on pH. When pH
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