ABSTRACT
A novel Ba(II)/TiO2-MCM-41 composite was synthesized using binary mixtures with Ba2+/TiO2 and MCM-41, and Ba2+ as a doping ion of TiO2. The specific surface area and pore structure characterizations confirm that a mesoporous structure with a surface area of 341.2 m2/g and a narrow pore size distribution ranging from 2 to 4 nm was achieved using Ba(II)/TiO2-MCM-41. Ba(II)/TiO2 particles were synthesized into 10-15 nm particles and were well dispersed onto MCM-41. The diffraction peaks in the XRD patterns of TiO2-MCM-41 and Ba(II)/TiO2-MCM-41 were all attributed to anatase TiO2. By taking advantage of MCM-41 and Ba2+, the photocatalytic performance of Ba(II)/TiO2-MCM-41 was remarkably enhanced by suppressing its rutile phase, by lowering the band gap energy, and by facilitating the dispersion of TiO2. Therefore, the photodegradation efficiencies of p-nitrobenzoic acid (4 × 10-4 mol/L) by various photocatalysts (60 min) under UV light irradiation are arranged in the following order: Ba(II)/TiO2-MCM-41 (91.7%) > P25 (86.3%) > TiO2-MCM-41 (80.6%) > Ba(II)/TiO2 (55.7%) > TiO2 (53.9%). The Ba(II)/TiO2-MCM-41 composite was reused for five cycles and maintained a high catalytic activity (73%).
ABSTRACT
The effect of bio-surfactant (rhamnolipid) on the remediation of crude oil and salt contaminated soil was investigated in this study. The experimental results indicated that there was a distinct decline of total petroleum hydrocarbon (TPH) concentration within the soil when using rhamnolipid during a remediation period of 30 days, with maximum TPH reduction of 86.97%. The most effective remediation that was observed was with rhamnolipid at a concentration of 2 CMC in soil solution, and a first-order TPH degradation rate constant of 0.0866 d(-1). The results also illustrated that salts in soil had a negative impact on TPH reduction, and the degradation rate was negatively correlated with NaCl concentration in soil solution. The analysis of soil TPH fractions indicated that there was a significant reduction of C13-C30 during the remediation process when using bio-surfactant.
