Adsorption Study Of Oil On Ti-pillared Exfoliated Graphite In Oil-water System

A novel Ti-pallared exfoliated graphite (Ti-EG) using TiCl4as titanium resourcewas prepared by two steps that one step was the low temperature hydrothermalprocess and second was the900℃bulk process. And the new adsorption materialwas used for the adsorb experiment of pure oil, oil slick and dissolved oil, andrecorded the oil adsorption, stability and the collection results of oil slick as thejudgment basis for properties of Ti-pallared exfoliated, simultaneously, got theinfluences of the temperature, time, ratio of liquid to solid, salinity, UV for the adsorbprogress of dissolved oil. And the SEM, XRD, contact angle measurement instrumentwere used for the microscopic characterization of Ti-pallared exfoliated graphite.Based on the analysis results of oil adsorption ratio and oil retention rate, weobtained the optimum conditions of preparing the Ti-pallared exfoliated graphite:expanded graphite was10g, titanium solution was10ml, reaction temperature was40℃, reaction time was6h, and the expanded volume of Ti-pallared exfoliatedgraphite was95ml/g. And Ti-pallared exfoliated graphite had a saturated adsorptionquantity of49.367g/g for vacuum pump oil, the oil slick maximum adsorptioncapacity was up to58.5g/g. The results by increasing the processing area showed thismaterial could be easy to collect and long-term stability of floating on water surfaceafter adsorbing oil.Experiment results showed that the adsorption kinetics of trace oil withTi-pallared exfoliated graphite is compatible with false second-order equation, and theequilibrium adsorption amount is0.1320g/g when the initial concentration of oil was31mg/L. The oil removal rate was increasing in10-20℃and was decreasing in20-35℃, and got the highest rate which was90.4%when the temperature was20℃.Meanwhile, the effect of salinity for the rate was in the same way, the removal ratewas increasing before the salinity of2.5%, and the rate was decreased to73.8%whenthe salinity increased from2.5%to4%. As the decreasing of liquid-solid ratio, the oilremoval rate could reach94.1%, and the adsorption process could be accelerated byUV irradiation, and can carried out the removal rate of90.4%in1h as same as theresults of3h in the dark conditions. The hydrophilicity of Ti-pallared exfoliated graphite that could make the materialcontact with the dissolving oil easily was enhanced by the low temperaturehydrothermal process. SEM results showed that the titanium dioxide crystals could besubsided slowly in the surface of graphite under this low temperature hydrothermalprocess, and grew into “flower” three-dimensional structure. Meanwhile, XRD resultsshowed rutile phase was the mainly after finished the low temperature hydrothermalprocess and the900℃bulking process and the brookite phase disappeared as thehydrothermal temperature raise to30℃. Contact angle analysis showed the contactangle of Ti-pallared exfoliated graphite was66.72°, had better hydrophilic than thecontact angle of exfoliated graphite which was94.37°. In Conclusion, the existence ofthe three-dimensional structure of rutile phase titanium dioxide made the materialhave the increasing hydrophilicity and can contact with the dissolving oil easily torealize the adsorption.