Effect of framework structure, pore size and surface modification on the adsorption performance of methylene blue and Cu²⁺ in mesoporous silica

A series of silica with diverse channel structures or pore diameters were synthesized via the hydrothermal method. Corresponding amine/nitro-modified materials were obtained by grafting, nitrating reaction, respectively. Textural and chemical properties were analyzed by Scanning electron micrograph (SEM), Small angle powder X-ray diffraction (SAXRD), Nitrogen adsorption-desorption measurement, Fourier transform infrared spectroscopy (FTIR), Thermogravimetric (TG) analysis and Zeta potential. Batch adsorption results revealed that distinct uptake capacities of Cu²⁺ and methylene blue occurred at the solid-liquid interface of prepared adsorbents. Especially, pure SBA-12-OH displayed the highest removal behavior toward methylene blue, mainly owing to its larger pore diameter. Amine-grafted SBA-12 (SBA-12-NH₂) presented higher affinity to Cu²⁺ than others, originating from the complexation function of amine groups and its superior framework structure. Moreover, their adsorption isotherms and kinetics were further investigated to explore the application in industrial operation system.