pH dependent Cu(II) and Pd(II) ions detection and removal from aqueous media by an efficient mesoporous adsorbent

• Mesoporous adsorbent is prepared for Cu(II) and Pd(II) detection and removal.
• Adsorbent can be captured Cu(II) and Pd(II) ions at pH dependent criterion.
• The adsorbent can selectively capture Cu(II) and Pd(II) ions with high sensitivity.
• Mesoporous adsorbent is able to ion-selective removal in environmental samples.

The pH dependent Cu(II) and Pd(II) ions detection and removal efficiency was investigated using ligand embedded mesoporous adsorbent. The mesoporous adsorbent was successfully prepared by 6-((2-(2-hydroxy-1-naphthoyl)hydrazono)methyl)benzoic acid (HMBA) embedded onto mesoporous silica monoliths. The mesoporous adsorbent has the large surface area-to-volume ratios and uniformly shaped pores, and its active sites are working for complexation to Cu(II) and Pd(II) ions with uniformly shaped pores in mesostructures. The adsorbent permits to fast and specific visualization of Cu(II) and Pd(II) ions detection and removal from aqueous media via a colorimetric signal visible to the naked eye. The mesoporous adsorbent enhanced the color formation by stable complexation during recognition and removal operations in a specific area. The extent of detection and removal efficiency was evaluated as a function of solution pH, contact time, initial concentration and diverse competing ions. The adsorbent showed very high adsorption capacity (182.39 and 172.53 mg/g for Cu(II) and Pd(II), respectively) and adsorption uptake on the adsorbent reaching equilibrium was also very rapid with extreme selectivity in ionic competition. Importantly, the mesoporous adsorbent was retaining functionality in spite of many chemical treatments during detection/removal-elution-regeneration cycles. Furthermore, the usage of mesoporous adsorbent to remove Cu(II) ions from the real environmental sample were performed. Therefore, the present study revealed that mesoporous adsorbent as low cost material could be used as potential adsorbent for the selective detection and removal of Cu(II) and Pd(II) ions from wastewater effluents.