Synthesis of Copper Supported on Natural Rubber-derived Mesoporous Carbon/Silica Composite for Efficient Adsorption of Caffeine

Abstract

Caffeine (CAF) removal from water resources is important because it is widely distributed and can be toxic to aquatic life. The copper supported on mesoporous carbon/silica composite (Cu/MCS) in this research was developed as a novel adsorbent to remove caffeine from aqueous solutions. The Cu/MCS material was prepared in two steps. The first step was the preparation of a precursor consisting of copper and natural rubber distributed inside a hexagonal mesoporous silica matrix (Cu/NR/HMS). Then, the composite was carbonized at high temperature under inert gas conditions to obtain Cu/MCS material. The amount of Cu loading in the MCS structure was studied. The Cu/MCS composites revealed a high level of copper distribution incorporated into the mesoporous carbon/silica framework as confirmed by Powder X-ray diffraction (XRD) and Scanning Electron Microscope and Energy Dispersive X-ray Spectrometer (SEM-EDS). The Cu/MCS materials possessed a high specific surface area (523–748 m2 g−1), large pore volume (0.80–0.86 cm3 g−1) and mesoporous diameter (3.07-3.30 nm). Fourier Transform Infrared Spectroscopy (FT-IR) and CHN analysis revealed a high amount of carbonaceous species dispersed in the Cu/MCS material. The Cu (0.010)/MCS, with copper loading of 1 mmol/g, revealed good properties for CAF removal when compared to other series of Cu/MCS adsorbents. Moreover, the Cu (0.010)/MCS composite exhibited the maximum adsorption capacity for CAF as 55.8 mg/g.