Synthesis of green nano sorbents for simultaneous preconcentration and recovery of heavy metals from water

Abstract

The wastewater containing Cd, Co, Fe, Cu, Cr, Mn, Ni and Pb ions are as trace metal pollutants. Water pollution caused by increment in industrialization and overpopulation reveals a major threat to human health. Adsorption is recognized as the effective and optimum method to remove water contaminations. The amorphous and porous form of silicon dioxide is silica gel widely used as an adsorbent. It can absorb moisture with traces of the target heavy metal ions. This research elaborates a simplistic, and reliable preconcentration column method highly developed for the determination of Cd²⁺, Fe³⁺, Co²⁺, Cr³⁺, Cu²⁺, Mn²⁺, Pb²⁺ and Ni²⁺ ions in model solutions and real water samples by flame atomic absorption spectrometry (FAAS). The proposed operation depends on the retention of the target ions from buffered model solutions on a silica gel filled up a column modified with vanadium(V) oxide sorbent followed by their desorption. SiO₂/V₂O₅ is an efficient adsorbent due to its low cost, eco-friendly and high availability. The adsorbent morphological and interfacial physicochemical characterization was done using scanning electron microscopy, and Fourier transmission infrared spectroscopy, respectively. The 2.92 value achieved for the point of zero charges supports the experimentation for the heavy metal efficient adsorption. Quantitative recoveries were achieved at pH 10 with 50 mg of SiO₂/V₂O₅ mass and adsorption capacity ranged from 28.96 μmol/g (Pb) to 214.86 μmol/g (Fe) with 1114.79 μmol/g in total. Simultaneous preconcentration effect was determined by the interference cations on the sorbent. The LOD varies from 8.42 to 50.56 μg/L and LOQ is achieved from 20.06 to 72.41 μg/L of 15 blank solutions. The developed preconcentration procedure was adequately implemented for the simultaneous analysis of eight metallic ions content in local river samples. The developed vanadium(V) oxide incorporated with silica gel is practicable as an economical and effective adsorbent to eliminate metallic ions from a liquid solution.

Keywords: Flame atomic absorption spectrometry and river water remediation; Heavy metal adsorption; Silica gel; Simultaneous preconcentration; Vanadium oxide.