Colloids and Surfaces A: Physicochemical and Engineering Aspects
Phosphate removal from water using freshly formed Fe–Mn binary oxide: Adsorption behaviors and mechanisms
Graphical abstract
Introduction
Phosphate is an essential nutrient element for living organisms. However, in aquatic environments, its excessively high concentration may deteriorate ecosystems and bring about subsequent water quality problems [1]. Therefore, it is crucial for researchers to develop effective technologies for phosphate removal in water and wastewater treatment systems. Among various available technologies for decontamination of phosphate, the adsorption method is relatively simple, economical, and highly efficient [2], [3].
In adsorption process, metal (hydr) oxides adsorbents such as iron, aluminum and manganese (hydr) oxides are widely used in water and wastewater treatments [4], [5]. In natural waters, these metal oxides are omnipresent and they are also found in combination with each other to form composite oxides [6], [7], which may display physicochemical properties different from those of their single component oxides. Thus the development of composite oxides adsorbents containing two (or more) different metal oxides has drawn great attention in recent years [7], [8], [9], [10], [11], [12]. In these studies, researchers only concentrate on adsorptive characteristics of relatively well-defined solid oxides for pollutants. However, in aquatic environments when these oxides are freshly formed, they often take on hydrous and amorphous forms with bulk surface properties distinctly different from aged solid oxides [3], [13]. Further, adsorptive capability of aged solid oxides might decrease due to drying preparations. In particular, these solid oxides are mostly powdery, making their direct engineering applications difficult. By contrast, freshly formed oxide suspensions can maintain high surface reactivity and adsorptive capability [14]. When utilized as adsorbents in water treatment, freshly formed oxide suspensions are easy to prepare in situ, dose in the water to be treated and subsequently rapid adsorptive reaction occurs. This is very favorable for its engineering applications in the treatment of water or wastewater, especially the remediation of phosphate-contaminated water body. Among various oxides, iron and manganese (hydr) oxides are well known due to their affinity towards phosphate [4], [15]. However, until now, very little is known about the adsorption behaviors of phosphate on freshly formed Fe–Mn binary oxide.
Thus, the objectives of the current study are to: (1) evaluate physicochemical properties of different freshly formed oxide suspensions (FMBO, FMMO, HFO and HMO) via determination of particle size distribution, zeta potential, X-ray diffraction (XRD) and other analytic techniques; (2) illustrate the characteristics of phosphate adsorption on freshly formed FMBO such as pH effects, adsorption kinetics, isotherms and effect of coexisting substances through batch experiments; and (3) propose the dominant mechanisms involved in phosphate removal by freshly formed FMBO using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) techniques.
Section snippets
Materials
In this study, with the exception of humic acid purchased from Sigma–Aldrich Corporation (USA), all other chemicals were purchased from Sinopharm Chemical Reagent Company (China) and were of analytical reagent grade. The phosphate standard stock solution was made from anhydrous potassium dihydrogen orthophosphate (KH2PO4). All solutions were prepared using deionized water.
Preparation of freshly formed oxides
Four kinds of freshly formed oxide suspensions were prepared in the current study, which included FMBO, FMMO, HFO and HMO.
Physicochemical properties of freshly formed oxides
Phosphate adsorption on metal oxides was significantly affected by their morphologies. In this study, the particle size distribution curves of FMBO, HFO and HMO suspensions are shown in Fig. 1. It can be found that the main particle size of FMBO ranged from 2 to 15 μm, which was different from that of HFO and HMO. The main particle size of HFO and HMO was approximately in the range of 5–35 μm and 0–23 μm, respectively. The SEM image (Fig. 2) of FMBO revealed that there were many micropores on the
Conclusions
Freshly formed FMBO suspension synthesized by the oxidation and coprecipitation method exhibited the highest selective adsorption capability towards phosphate as compared to FMMO and their simple oxide (i.e., HFO and HMO). The surfaces of FMBO were found to be rough and nanostructured. Zeta potential, XRD, EDAX and XPS analyses showed that ferric oxide was enriched on the surface of binary oxide, resulting in the surface mineralogy (XRD) and charge properties of FMBO microparticles similar to
Acknowledgments
This study was funded by the National Science Foundation for Distinguished Young Scholars of China (No. 51225805), the National Natural Science Foundation of China (Nos. 51108298 and 51138009) and the Natural Science Foundation of Tianjin (No. 12JCYBJC14800). The authors also acknowledge the financial support from the Research Fund of Tianjin Key Laboratory of Aquatic Science and Technology (No. TJKLAST-2011-13).
References (29)
- et al.
Enhanced trace phosphate removal from water by zirconium(IV) loaded fibrous adsorbent
Water Res.
(2011) - et al.
Comparison of low-cost and engineered materials for phosphorus removal from organic-rich surface water
Water Res.
(2011) - et al.
Development of chemically engineered porous metal oxides for phosphate removal
J. Hazard. Mater.
(2011) - et al.
Iron and aluminium based adsorption strategies for removing arsenic from water
J. Environ. Manag.
(2011) - et al.
Cd2+ sorption characteristics of iron coated silica
Desalination
(2011) - et al.
Removal of phosphate from water by a Fe–Mn binary oxide adsorbent
J. Colloid Interface Sci.
(2009) - et al.
Arsenic removal using hydrous nanostructure iron(III)–titanium(IV) binary mixed oxide from aqueous solution
J. Hazard. Mater.
(2009) - et al.
Fluoride removal efficiency from aqueous solution by synthetic iron(III)–aluminum(III)–chromium(III) ternary mixed oxide
Desalination
(2010) - et al.
Mn–Ce oxide as a high-capacity adsorbent for fluoride removal from water
J. Hazard. Mater.
(2011) - et al.
Defluoridation by freshly prepared aluminum hydroxides
Chem. Eng. J.
(2011)
Temperature effect on the mechanism of phosphate anions sorption by β-MnO2
Chem. Eng. J.
Effects of silicate, sulfate, and carbonate on arsenic removal by ferric chloride
Water Res.
Adsorptive selenite removal from water using iron-coated GAC adsorbents
Water Res.
Development of polymer-based nanosized hydrated ferric oxides (HFOs) for enhanced phosphate removal from waste effluents
Water Res.
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