Abstract
In the present work, beta-calcium pyrophosphate (β-Ca2P2O7) was investigated as a potential adsorbent for the removal of heavy metal ions from water. Single-phase β-Ca2P2O7 powders were synthesized by a simple, scalable and cost-effective wet precipitation method followed by annealing at 800 °C, which was employed for the conversion of as-precipitated brushite (CaHPO4∙2H2O) to β-Ca2P2O7. Physicochemical properties of the sorbent were characterized by means of X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA/DSC), scanning electron microscopy (SEM) and low temperature adsorption–desorption of nitrogen (BET method). The synthesized powders consisted of porous plate-like particles with micrometer dimensions. Specific surface area calculated by the BET method was found to be 7 m2 g−1. For the estimation of sorption properties, the aqueous model solutions containing different metal ions (Al3+, Cd2+, Co2+, Cu2+, Fe2+, Mn2+, Ni2+, Pb2+, Sn2+, Sr2+ and Zn2+) were used. The adsorption test revealed that β-Ca2P2O7 demonstrates the highest adsorption capacity for Pb2+ and Sn2+ ions, while the lowest capacity was observed towards Sr2+, Ni2+ and Co2+ ions. The optimal pH value for the removal of Pb2+ ions was determined to be 2, which is also related to the low solubility of β-Ca2P2O7 at this pH. The adsorption capacity towards Pb2+ ions was calculated as high as 120 mg g−1.
Highlights
Nowadays, water purification is of essential importance due to the increased contamination, which brings a serious risk to public health and other forms of life on the earth.In order to reduce the contamination, a number of methods and techniques have been employed, including ion exchange, membrane separation, electrolysis, chemical precipitation and adsorption [1,2]
The phase crystallinity and purity of as-synthesized powders were characterized by means of X-ray diffraction (XRD) analysis
Single-phase β-Ca2 P2 O7 was synthesized by a wet precipitation process followed by thermal treatment at 800 ◦ C
Summary
In order to reduce the contamination, a number of methods and techniques have been employed, including ion exchange, membrane separation, electrolysis, chemical precipitation and adsorption [1,2]. Among these methods, adsorption can be characterized as simple, efficient and low-cost approach. A great variety of sorbents can be employed for water purification, including organic, inorganic and hybrid materials [3]. The search for and development of new materials for the fast and efficient removal of pollutants from water remains the task of the highest priority
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