| Phosphate(P), an indispensable macronutrient widely found in aquatic environments, is highly required for the growth of living organisms and the normal functioning of ecos ystems. However, excess P inputs to aquatic systems can lead to over-fertilization, and causes eutrophication and ecos ystem degradation. Therefore, there is an increasing demand for removal of phosphorus.A variety of P removal techniques are available for phosphorus removal, including chemical precipitation, adsorption methods and biological treatments. Among these available treatment processes aforementioned, adsorption is considered to be an effective approach due to its easily-handle operation, low cost, and eco-friendl y characters. In recent investigations, iron-based materials and zirconium-based materials have been paid more attention in controlling P pollution due to their high binding affinity towards P, non-toxicity and acceptable cost. Activated carbon fiber(ACF), a highly microporous carbon material which shows favorable adsorption performances due to its nano-structure, abundant micrometer porosity, high specific surface area and uniform micropore size distributions, is believed to have potential applications in adsorption. Hence, a n ew adsorbent for the removal of P from aqueous solution was prepared by loading zirconium and iron particles on the surface of ACF(ACF-ZrFe) simultaneously.Both single factor and orthogonal experiments were designed for the optimizion of preparation con ditions, and to investigate the adsorption behavior of phosphate by a ACF-ZrFe with the adsorption kinetics and i sotherm, and the effect of adsorption conditions(phosphate concentration ?dosage?p H?temperature and interfere ions) were also considered. In order to achieve the efficient of regeneration of adsorbent, this article also explored the regeneration method and optimized phosphorus recovery parameter. Moreover, the mechanism of phosphate ions onto ACF-ZrFe was also proposed by anal yzing the behavior of phosphate adsorption and characterization methods(SEM ? FT-IR? XPS). All the results were indicated as follows. 1? A new adsorbent for the removal of P from aqueous solution was prepared by loading zirconium and iron particles on the surface of ACF and the behavior of adsorption phosphate for ACF-ZrFe implied its promise for phosphate removal from aqueous solutions. 2? The orthogonal experiments were designed for the optimizion of preparation conditions, and the optimum preparation conditions were the n(Zr)/n(Fe) ratio of 7:3, the total concentration of 0.1 mol/L, and the ultrasonic time of 10 min. 3?Static adsorption of ACF-ZrFe clearl y showed that ad sorption amount increased with the increase of initial phosphate concentration and temperature and de crease of dosage. In addition, adsorption amount of adsorption increased and then decreased with the increase of p H in solution. Moreover, co-existing ions including sulfate, chloride, nitrate and fluoride had a certain effect on the uptake of P with the order of F->NO3->Cl->SO42-. 4? The adsorption isotherm could be well described by the Langmuir model, and the maximum P adsorption capacity was estimated to be 27.03 mg P/g. The kinetics data were well fitted to pseudo-second-order equation. 5 ? The order of the regeneration efficiency of ACF-ZrFe was as follow: Na OH >Na Cl >HNO3 when desorption time and desorption reagent concentration. 6? Ligands exchange and electrostatic interactions were the main mechanisms for the P adsorption of ACF-ZrFe. |
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