• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.8
• /
• pp.428-434
• /
• 2016

This study evaluated the efficacy of Ti-based coagulants on phosphorus (P) removal from municipal wastewater and compared them with Al-based coagulants. Jar test experiments were performed at various chemical doses and OH/Ti molar ratio (B value). The higher the intial phosphate ($PO_4-P$) concentration, the lower the [Ti]/[P] to reach a residual concentration below 0.2 mg P/L. Removal efficiencies of total phosphorus increased with an increased coagulant dose but decreased after the efficiencies reached their maximum value regardless of coagulant or B value. On the other hand, $PO_4-P$ removal showed an increasing trend with an increased coagulant dose, reaching the plateau value under large coagulant dose conditions for both Ti- and Al-based coagulants regardless of B value. The chemical dose of Ti-based coagulants was approximately twice higher than that of Al-based coagulants with the same P-removal efficiency. The coagulation efficiency was influenced by different B values.

• Applied Chemistry for Engineering
• /
• v.10 no.1
• /
• pp.73-79
• /
• 1999

The superstructured $Li_{4/3}Ti_{5/3}O_4$ was prepared by sol-gel process using a mixed solution of lithium acetate (LA) and titanium n-butoxide (TNB). The gel phase was obtained by adding ammonia water ($NH_4OH/TNB$ mole ratio of 0.35) and water ($H_2O/TNH$ mole ratio of 3.5) into the clear sol that was prepared after mixing TNB/LA mole ratio of 5/4 with AA/TNB mole raio of 0.125. It was found that the most suitable $Li_{4/3}Ti_{5/3}O_4$ was obtained by heat treatment of xerogel at $600^{\circ}C$ for 30 hrs. The synthesized $Li_{4/3}Ti_{5/3}O_4$ showed an initial discharge capacity of 174 mAh/g and the capacity loss of about 27.3% during 25 cycles in Li/1M $LiClO_4(in\;PC)/Li_{4/3}Ti_{5/3}O_4$ at current density of $0.15mA/cm^2$ and the voltage range of 0.5~3.0 V.

• Korean Chemical Engineering Research
• /
• v.44 no.4
• /
• pp.399-403
• /
• 2006

There has been numerous reports for the synthesis of mesoporous $TiO_2$ thin films due to not only the high surface area and regular mesoscale pores but also wide band gap and photo activity. However, the synthesis has been restricted by the limited reproducibility mainly due to the extraordinarily fast hydrolysis and condensation rate of titania precursors. In this report, molar composition of reaction batch (HCl/Ti and Ti/P123) and exterior condition (humidity and temperature) during coating and anealing process. Thereafter, the mesoporous $TiO_2$ thin films were characterized by XRD and TEM

• Journal of the Korean Applied Science and Technology
• /
• v.34 no.4
• /
• pp.746-755
• /
• 2017

In this study, $CeO_2/TiO_2$ nanoparticle with structure of core and shell was synthesized by growing $TiO_2$ onto the surface of $CeO_2$ according to hydrolysis of $Ti(SO_4)_2$. Reaction time, temperature, concentration of $CeO_2$ slurry, pH control of $Ti(SO_4)_2$ were optimized about synthesis of $CeO_2/TiO_2$ core-shell nanoparticle. It was found that optimal mole ratio range of $CeO_2:TiO_2$ was 1:0.2~1.1, the optimal concentration of $CeO_2$ slurry was 1 %, and the optimal reaction temperature was $50^{\circ}C$. The optimal concentration of $CeO_2$ slurry could be increased up to 10 % by adjusting the pH of $Ti(SO_4)_2$ to 1 using $NH_4OH$ and adding to $CeO_2$ slurry. If reaction was carried at $80^{\circ}C$ or higher, the separated $TiO_2$ particles were obtained instead of $CeO_2/TiO_2$ core-shell nanoparticles. The optimal reaction temperature was $50^{\circ}C$ at which good shaped core-shell structure of $CeO_2/TiO_2$ was obtained.

• Korean Chemical Engineering Research
• /
• v.46 no.5
• /
• pp.845-851
• /
• 2008

Oxidative desulfurizaton of model sulfur compounds and Industrial diesel fuel(LCO; Light Cycle Oil) over Ti-grafted SBA-15 catalyst was studied in a batch reactor with tert-Butyl Hydroperoxide(TBHP) as oxidant. Effects of Ti loading, TBHP/Sulfur mole ratio, reaction temperature on ODS activity and kinetic parameters were investigated. Ti-grafted SBA-15 catalyst showed higher sulfur removal activity in the oxidative desulfurization reaction of refractory sulfur compounds(DBT and 4, 6-DMDBT) and LCO, suggesting that Ti-grafted SBA-15 catalyst could be a good candidate for ODS catalyst.

• Applied Chemistry for Engineering
• /
• v.23 no.2
• /
• pp.148-152
• /
• 2012

Anatase and anatase/rutile $TiO_2$ samples were prepared at $HNO_3$/TTIP molar ratio of 0.1, 0.5, 1.0, and 1.5 to study the effects of the physical properties of $TiO_2$ on photocatalytic decomposition of methylene blue. The physical properties of the samples were measured with XRD, SEM, TEM, BET, FT-IR, and UV-vis spectroscopy. Anatase phase was observed at $HNO_3$/TTIP of 0.1 and anatase/rutile phases were observed at $HNO_3$/TTIP of 0.5~1.5. Rutile crystal phase, mesopore size between $TiO_2$ nanoparticles, and surface OH group on $TiO_2$ sample were gradually increased with increasing the molar ratio of $HNO_3$/TTIP and the residual methylene blue concentration before UV irradiation decreased from 78.0 to 53.3%. After UV irradiation, the residual methylene blue concentrations of the samples prepared at $HNO_3$/TTIP of 0.1, 0.5, 1.0, and 1.5 were 20, 14, 11, and 23%, respectively, and the sample prepared at $HNO_3$/TTIP of 1.0 showed the best photocatalytic ability.