Improving copper(II) ion detection and adsorption from wastewater by the ligand-functionalized composite adsorbent

Abstract

The functional organic ligand of 4-tert-Octyl-4-((phenyl)diazenyl)phenol (TPDP) was immobilized directly onto the mesoporous silica for the fabrication of composite adsorbent to detect and remove the toxic copper (Cu(II)) ions from contaminated water. The mesoporous silica and the composite adsorbent were characterized systematically using different instrumentations. Upon addition of a trace amount of Cu(II) with composite adsorbent, a significant color was formed to visualize the Cu(II) ion detection at optimum experimental protocol. The pH played a key factor in the detection and removal operation and the optimum pH was 4.0 for this study. The effect of pH, color optimization, contact time, competing ions, and concentration was assessed systematically both in the detection and removal operations. The limit detection by the composite adsorbent to Cu(II) ion was 0.28 µg/L. The diverse metal ions did not interfere during the Cu(II) ion detection and removal by the composite adsorbent and complied with the high sensitivity for onsite uses as potential materials. The proposed adsorbent also exhibited high adsorption capacity and was well-fitted in the Langmuir adsorption isotherms in monolayer coverage and the maximum adsorption capacity was as high as 184.73 mg/g. The Cu(II) ion was eluted from the composite adsorbent using 0.15 M HCl and then simultaneously regenerated into the initial stage without losing its major functionality for the next use operation. However, the adsorption efficiency was slightly decreased after several cycles of use according to the data. Then it is estimated that the fabricated ligand-based composite adsorbent in the real waste sample treatment for detection and removal of Cu(II) ions as a low-cost material without using highly sophisticated instrumentations.