Sustainable composite sensor material for optical cadmium(II) monitoring and capturing from wastewater

Abstract

Abstract In this study, an optical sensor material was fabricated for sustainable detection and adsorption of cadmium (Cd(II)) ion in aqueous solution with specific color formation. The sulphur containing organic functional ligand was grafted onto the mesoporous silica monolith via direct immobilization method through chemical and electrostatic interaction. The sensor material was exhibited an enhanced sensitivity and distinct color and spectral response to Cd(II) ion in aqueous solution. Larger immobilization capacity of organic ligand on the carrier silica to stronger accumulation for Cd(II), and smaller one made the optical sensor have a faster and more sensitive response to the Cd(II) ion at optimum condition. The influence of pH, limit of detection, ion selectivity and Cd(II) ion adsorption capacity and the effect of eluent for the stripping of Cd(II) ion from sensor material over elution efficiency were measured. The sensor material offered a simple procedure in ultra-trace Cd(II) sensing optically without using high tech instruments. The Cd(II) ion detection limit of the presented sensor material was 0.36 µg/L at optimum conditions. The proposed sensor was exhibited with large surface area-to-volume ratios and uniformly mesostructures shaped pores that were actively working to selective capturing of Cd(II) ion. The adsorption data were well fitted to the Langmuir model and the maximum adsorption capacity was 167.33 mg/g. The sensor was capable to detected the Cd(II) ion even in the presence of a high amount of coexisting diverse metal ions. Moreover, the adsorbed Cd(II) ion was completely eluted with 0.30 M HCl and simultaneously regenerated into the initial form for the next operation after washing with water. Therefore, the optical sensor material exhibited good stability and reusability which made it efficient for various adsorptive removal and detection applications.