Magnetically separable and reusable zinc ferrite/reduced graphene oxide ( ZnFe2O4/rGO) nanocomposite has been prepared by hydrothermal method. The results illustrate that the construction of ZnFe2O4 and rGO occur concurrently in a hydrothermal reaction that initiates the formation of rGO-wrapped ZnFe2O4 nanospheres. The morphological and structural features of the ZnFe2O4/ rGO nanocomposites reveal that the rGO nanosheets anchored to the ZnFe2O4 sphere act as a self-protective clamping layer to avoid the photo corrosion effect under photo irradiations. The nanocomposites express the soft magnetic behavior with high saturation magnetization under annealing temperature at 300 °C, which may attribute to the well-defined crystalline structure and surface defects. In addition, the GZF 300 nanocomposites exhibit the enhanced photocatalytic degradation over Rhodamine B dye which is 3.4, 1.15, and 1.32 times higher than that of ZF, GZF, and GZF 600 over under visible irradiation in 120 min. The GZF 300 nanocomposites demonstrate their ability to degrade RhB efficiently, even after several photocatalysis cycles with high catalyst recovery by its magnetically separable behavior. The high densities of oxygen defects improvise electron transfer from ZnFe2O4 to rGO and delay the recombination process of the nanocomposite, resulting in enhanced visible photocatalytic activity. The strong magnetic properties of rGO wrapped ZnFe2O4 nanocomposite catalysts the easy separation from the suspension system for multiple usages in water treatment.

단순 침전법으로 제조한 CdZnS/ZnO 광촉매를 이용하여 가시광선하에서 메틸렌블루의 광분해 반응에 대한 연구를 수행하였다. X선 회절분석법과 UV-vis 확산반사 분광법 등을 이용하여 제조된 촉매들의 물리화학적 특성을 분석하였다. 그리고 CdZnS/ZnO 광촉매의 활성을 조사하고 CdS 및 TiO2와 비교 검토하였다. CdZnS/ZnO 광촉매는 자외선뿐만 아니라 400nm에서 600nm 범위의 가시광선 영역에 있어서도 우수한 광흡수 특성을 나타내었다. 가시광선하에서 메틸렌 블루의 광분해 반응에 대해서 CdZnS/ZnO 광촉매는 CdS 와 TiO2 보다 우수한 광촉매 활성을 나타내는 것을 알 수 있었다. 그리고 가시광선하에서의 메틸렌블루의 광분해 반응에는 광촉매 반응뿐만 아니라 감광반응도 관여하고 있음을 확인할 수 있었다.

SnS-TiO2 nanocomposites are synthesized using simple, cheap, and less toxic SnCl2 as the tin (II) precursor. The prepared nanoparticles are characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectra (DRS). The XRD and TEM results indicate that the prepared product has SnS nanoparticles and a grain diameter of 30 nm. The DRS demonstrate that SnS-TiO2 possesses the absorption profile across the entire visible light region. The generation of reactive oxygen species is detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and photocatalytic effect increase with the modified SnS. Excellent catalytic degradation of Texbrite BA-L (TBA) solution is observed using the SnS-TiO2 composites under visible light irradiation. It is proposed that both the strong visible light absorption and the multiple exciton excitations contribute to the high visible light photocatalytic activity.

AC and ZnS modified TiO2 composites (AC/ZnS/TiO2) were prepared using a sol-gel method. The composite obtained was characterized by Brunauer-Emmett-Teller (BET) surface area measurements, X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, scanning electron microscope (SEM) analysis, and according to the UV-vis absorption spectra (UV-vis). XRD patterns of the composites showed that the AC/ZnS/TiO2 composites contain a typical single and clear anatase phase. The surface properties as observed by SEM present the characterization of the texture of the AC/ZnS/TiO2 composites, showing a homogenous composition in the particles showing the micro-surface structures and morphology of the composites. The EDX spectra of the elemental identification showed the presence of C and Ti with Zn and S peaks for the AC/ZnS/TiO2 composite. UV-vis patterns of the composites showed that these composites had greater photocatalytic activity under visible light irradiation. A rhodamine B (Rh.B) solution under visible light irradiation was used to determine the photocatalytic activity. The degradation of Rh.B was determined using UV/Vis spectrophotometry. An increase in the photocatalytic activity was observed. From the photocatalytic results, the excellent activity of the Y-fullerene/TiO2 composites for the degradation of methylene blue under visible irradiation could be attributed to an increase in the photo-absorption effect caused by the ZnS and to the cooperative effect of the AC.

분리막을 이용한 수처리 공정에서 유입 수에 함유된 부유물질이나 기타 오염물질이 막 표면 또는 내부에 축적 흡착 등의 막 오염현상으로 인해 막 성능 감소와 함께 막 분리 공정에 큰 영향을 미치게 된다. 본 연구에서는 막 표면에서의 막 오염현상을 실시간으로 모니터링 할 수 있는 기술을 연구하였다. 투명한 오염물질에 의한 분리막 표면 오염을 측정하기 위해 막 표면에 360 nm 파장의 가시광선을 조사하여 이미지를 R. G. B 값으로 추출하여 막의 오염현상을 실시간으로 모니터링 하였다. 추출된 이미지 중 400~499 nm 파장영역인 B 값이 가장 강도가 강하게 나타났다. 막 오염정도의 변화를 이미지의 강도 차이로 관찰함으로써 실시간 분석이 가능함을 확인하였다.

Graphene oxide (GO)-titania composites have emerged as an attractive heterogeneous photocatalyst that can enhance the photocatalytic activity of TiO2 nanoparticles owing to their potential interaction of electronic and adsorption natures. Accordingly, TiO2-GO mixtures were synthesized in this study using a simple chemical mixing process, and their heterogeneous photocatalytic activities were investigated to determine the degradation of airborne organic pollutants (benzene, ethyl benzene, and o-xylene (BEX)) under different operational conditions. The Fourier transform infrared spectroscopy results demonstrated the presence of GO for the TiO2-GO composites. The average efficiencies of the TiO2-GO mixtures for the decomposition of each component of BEX determined during the 3-h photocatalytic processes were 26%, 92%, and 96%, respectively, whereas the average efficiencies of the unmodified TiO2 powder were 3%, 8%, and 10%, respectively. Furthermore, the degradation efficiency of the unmodified TiO2 powder for all target compounds decreased during the 3-h photocatalytic processes, suggesting a potential deactivation even during such a short time period. Two operational conditions (air flow entering into the air-cleaning devices and the indoor pollution levels) were found to be important factors for the photocatalytic decomposition of BEX molecules. Taken together, these results show that a TiO2-GO mixture can be applied effectively for the purification of airborne organic pollutants when the operating conditions are optimized.