Removing methylene blue from water: A study of sorption effectiveness onto nanoparticles-doped activated carbon.

In this present study, silver (Ag) and titanium dioxide (TiO) nanoparticles were successfully deposited on coconut shell-derived activated carbon (CSAC), to synthesize a novel nanocomposite (CSAC@AgNPs@TiONPs) for the adsorption of Methylene Blue (MB) dye from aqueous solution. The fabricated CSAC@AgNPs@TiONPs nanocomposite was analyzed by Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscope (TEM) equipped with Energy Dispersive X-ray spectroscopy (EDS) detector, X-ray Photoelectron Spectroscope (XPS), and Brunauer-Emmett-Teller (BET). The successful deposition of AgNPs and TiONPs on CSAC surface was revealed by the TEM/EDX, SEM, and XPS analysis. The mesopore structure of CSAC@AgNPs@TiONPs has a BET surface area of 301 m/g. The batch adsorption studies were conducted and the influence of different parameters, i.e., adsorbent dose, adsorption time, initial dye concentration, pH and temperature were investigated. The nonlinear isotherm and kinetic modelling demonstrated that adsorption data were best fitted by Sips isotherm and pseudo-second-order models, respectively. The maximum adsorption capacity of MB onto CSAC@AgNPs@TiONPs by the Sips model was 184 mg/g. Thermodynamic results revealed that the adsorption was endothermic, spontaneous and physical in nature. CSAC@AgNPs@TiONPs revealed that MB absorption by CSAC@AgNPs@TiONPs was spontaneous and endothermic. The uptake capacity of MB was influenced significantly by the presence of competing ions including, NO, HCO Ca, and Na. Repeated tests indicated that the CSAC@AgNPs@TiONPs can be regenerated and reused six times before being discarded. The primary separation mechanism between MB dye and CSAC@AgNPs@TiONPs was the electrostatic interaction. Thus, CSAC@AgNPs@TiONPs was an outstanding material, which displayed good applicability in real water with ≥ 97% removal of MB dye.