Nano-silica and nano-zeolite synthesized from barley grass straw for effective removal of gasoline from aqueous solution: a comparative study

Abstract

In this study, nano-silica (NS) was synthesized from barley grass straw through a combination of acid and heat treatments. The synthesized nano-silica was then used as the precursor silica material for the synthesis of nano-zeolite (NZ). NS and NZ were characterized using X-ray fluorescence (XRF), dynamic light scattering (DLS), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Bruner–Emmett–Teller method (BET) measurements. The NS and NZ particles were observed to be hydrophobic and possess large surface areas (128 and 106 m2/g, respectively); this results in high uptake of gasoline compared to other sorbents. NS and NZ particles (0.5 g) were each applied to a 40 mg/g concentration of gasoline-contaminated water at pH 7, which resulted in high uptake efficiencies of 95% for NS and 85% for NZ. Kinetics and equilibrium studies were performed, and the obtained results were processed to produce relevant parameters. The sorption was significantly effective, and the percentage of contaminants removed was seen to depend heavily on the amount of sorbent added. The kinetics results indicated that the second-order sorption kinetics exhibited the best fit for the gasoline sorption data. It was also apparent that the Langmuir isotherms described the sorption the most closely. The results suggest that nanoparticles provide a clean-up solution for petroleum spillage and contamination in water.