scholarly journals PHOTOCATALYTIC REMOVAL OF TR I- AND HEXA-VALENT CHROMIUM IONS FROM CHROME-ELECTROPL ATING WASTEWATER

2017 ◽  
Vol 22 (4) ◽  
pp. 355 ◽  
Author(s):  
Puangrat Kajitvichyanukul ◽  
Chulaluck Changul
Keyword(s):  
Reduction Process ◽  
Environmental Pollutant ◽  
Photocatalytic Reduction ◽  
Solution Ph ◽  
Total Chromium ◽  
Chromium Ions ◽  
Photocatalytic Removal ◽  
Result Show ◽  
Dioxide Suspension ◽  
Chrome Electroplating

A novel technique based on photocatalysis was applied to eliminate chromium ions, a toxic hazardous environmental pollutant. The photoreduction of each species of chromium (total, hexavalent, and trivalent chromiums) from chrome-electroplating wastewater was investigated using a titanium dioxide suspension under irradiation by a low-pressure mercury lamp. The initial concentration of total chromium was 300 mg/l. The applied conditions were the direct photocatalytic reduction process at pH 3.65 and the indirect photocatalytic reduction with added hole scavengers at the same solution pH. Results from both processes were comparatively discussed. Result show that chromium was not efficiently removed by direct photoreduction. In contrast, with the adding of hole scavengers, which were formate ions, the photoreduction of chromium was very favorable. Both hexavalent and trivalent chromiums were efficiently removed. The photocatalytic mechanism is purposed in this study. 

scholarly journals Reduction of chromium (VI) from aqueous solution by biomass of Cladosporium cladosporioides

2017 ◽  
Vol 76 (9) ◽  
pp. 2494-2502 ◽  
Author(s):  
María Teresa Garza-González ◽  
Jonathan Eduardo Ramírez-Vázquez ◽  
María de los Ángeles García-Hernández ◽  
María Elena Cantú-Cárdenas ◽  
Adriana Liñan-Montes ◽  
...  
Keyword(s):  
Reduction Process ◽  
Cladosporium Cladosporioides ◽  
Total Chromium ◽  
Isothermal Model ◽  
Process Comparison ◽  
Chromium Vi ◽  
Before And After ◽  
Effects Of Ph ◽  
Pseudo Second Order ◽  
Adsorption Reduction

Abstract The capacity of Cladosporium cladosporioides biomass for removal of Cr(VI) in aqueous solutions was evaluated. A 2 × 2 factorial experiment design was used to study the effects of pH and biomass doses. Lower pH values and larger biomass doses increased the capacity of C. cladosporioides biomass for removal of Cr(VI), reaching a reduction capacity of 492.85 mg g−1, a significantly higher value compared to other biomass reported. Cr(VI) removal kinetic rates followed a pseudo-second order model, like other fungal biomass reported previously. The apparent adsorption process was described well by the Freundlich isothermal model. However, determination of total chromium indicated that adsorption of Cr(VI) was followed by a redox reaction that released proportional quantities of Cr(III) into the experimental supernatant, suggesting a parallel adsorption-reduction process. Comparison of Fourier transform infrared spectroscopy spectra of C. cladosporioides biomass before and after the reduction process demonstrated the involvement of positively charged amino groups in the Cr(VI) adsorption-reduction process.

Photocatalytic removal of cyanide with illuminated TiO2

2011 ◽  
Vol 64 (7) ◽  
pp. 1383-1387 ◽  
Author(s):  
M. Shirzad Siboni ◽  
M. R. Samarghandi ◽  
J.-K. Yang ◽  
S.-M. Lee
Keyword(s):  
Aqueous Solutions ◽  
Langmuir Isotherm ◽  
Industrial Wastewater ◽  
Photocatalytic Oxidation ◽  
Maximum Adsorption Capacity ◽  
Photocatalytic Reaction ◽  
Solution Ph ◽  
Cyanide Concentration ◽  
Photocatalytic Removal ◽  
Oxidation Efficiency

Effects of TiO2 dosage, pH and initial cyanide concentration on the removal efficiency of cyanide from aqueous solutions with illuminated TiO2 have been investigated. Adsorption and oxidation were recognized as significant processes for the elimination of cyanide. From the Langmuir isotherm, the maximum adsorption capacity was determined as 17.24 mg/g at pH 7. Adsorbed amount of cyanide slightly increased as the TiO2 dosage increased. However, as no significant increase was observed above 1 g/L TiO2, an optimum TiO2 dosage was determined as 1 g/L. Photocatalytic oxidation efficiency of cyanide was greatly affected by the solution pH. It increased as the solution pH decreased. The photocatalytic oxidation efficiency after 120 min was 80.4% at pH 3 while it was only 20.4% at pH 11. Photocatalytic oxidation of cyanide was well described by the second-order kinetics. Photocatalytic reaction with illuminated TiO2 can be effectively applied to treat industrial wastewater contaminated with cyanide.

Highly efficient and stable photocatalytic reduction of CO2 to CH4 over Ru loaded NaTaO3

2015 ◽  
Vol 51 (36) ◽  
pp. 7645-7648 ◽  
Author(s):  
Mu Li ◽  
Peng Li ◽  
Kun Chang ◽  
Tao Wang ◽  
Lequan Liu ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Electron Donor ◽  
Water Oxidation ◽  
Reduction Process ◽  
Photocatalytic Reduction ◽  
Highly Efficient ◽  
Main Effect ◽  
Reduction Of Co2

An efficient and stable photocatalytic activity was obtained over NaTaO3 by introducing electron donor (H2) into the CO2 reduction process with water and loaded Ru as cocatalysts. The main effect of the electron donor was found to release the peroxide intermediates of the half reaction for water oxidation.

scholarly journals Adsorption of Nickel and Chromium Ions by Amine-Functionalized Silica Aerogel

2018 ◽  
Vol 156 ◽  
pp. 03014
Author(s):  
Sudarat Sertsing ◽  
Thanaphat Chukeaw ◽  
Sitthiphong Pengpanich ◽  
Bawornpong Pornchuti
Keyword(s):  
Silica Aerogel ◽  
Solution Concentration ◽  
Functionalized Silica ◽  
Solution Ph ◽  
Chromium Ions ◽  
Amine Functionalized ◽  
Adsorption Capacities ◽  
Equilibrium Data ◽  
Langmuir Isotherm Model ◽  
Adsorption Equilibrium Data

In this study, silica aerogel was synthesized by drying at atmospheric pressure and modified further with aminopropyl triethoxysilane (APTES). The amine-functionalized silica aerogel was investigated as an adsorbent for removal of nickel and chromium ions. The effect of contact time, solution pH, and initial solution concentration were studied. The equilibrium was achieved within 60 min. The optimum pH was found to be 4. Adsorption equilibrium data were agreed fairly well with Langmuir isotherm model. Adsorption capacities for nickel and chromium ions were found to be 40.32 mg/g and 46.08 mg/g, respectively.

scholarly journals In-situ preparation of MOFs/SiC/PVA-Co-PE nanofiber membranes for efficient photocatalytic reduction of CO2

2021 ◽  
Vol 252 ◽  
pp. 02056
Author(s):  
Xianwei Fan ◽  
Ran Zhao ◽  
Haoxuan Hu ◽  
Junyi Liu ◽  
Yahui Nie ◽  
...  
Keyword(s):  
Visible Light ◽  
Reduction Process ◽  
Reduction Reaction ◽  
Photocatalytic Reduction ◽  
Nanofiber Membrane ◽  
Characterization Methods ◽  
In Situ Preparation ◽  
Light Region ◽  
Composite Nanofiber ◽  
Reduction Of Co2

In this paper, we prepared a polyvinyl alcohol-polyethylene (PVA-Co-PE) composite nanofiber membrane catalyst decorated by Fe-MOFs/SiC and completed the photocatalytic reduction of CO2 performance. The results show that the CO2 conversion rate of composite film materials under visible light irradiation is increased by 31 times compared with powdered Fe-MOFs/SiC materials. Through SEM, XRD, BET, FTIR, DRS and other characterization methods, the influencing factors of the photocatalytic CO2 reduction process of the composite nanofiber membrane were investigated. The synergistic effect of Fe-MOFs/SiC and nanofiber membrane photocatalysis is beneficial to electron-hole pairs. The effective separation and strong absorption in the visible light region make it exhibit excellent photocatalytic activity in the photocatalytic CO2 reduction reaction.

scholarly journals Photocatalytic Reduction of Cr (VI) over g-C3N4 Photocatalysts Synthesized by Different Precursors

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 7054
Author(s):  
Juan Liang ◽  
Chengjun Jing ◽  
Jiarong Wang ◽  
Yupawang Men
Keyword(s):  
Surface Area ◽  
Carbon Nitride ◽  
Hydrogen Adsorption ◽  
Direct Reduction ◽  
Reduction Process ◽  
Photocatalytic Reduction ◽  
Pyrolysis Process ◽  
Photogenerated Electrons ◽  
One Step ◽  
Amine Groups

Graphitic carbon nitride (g-C3N4) photocatalysts were synthesized via a one-step pyrolysis process using melamine, dicyandiamide, thiourea, and urea as precursors. The obtained g-C3N4 materials exhibited a significantly different performance for the photocatalytic reduction of Cr(VI) under white light irradiation, which is attributed to the altered structure and occupancies surface groups. The urea-derived g-C3N4 with nanosheet morphology, large specific surface area, and high occupancies of surface amine groups exhibited superior photocatalytic activity. The nanosheet morphology and large surface area facilitated the separation and transmission of charge, while the high occupancies of surface amine groups promoted the formation of hydrogen adsorption atomic centers which were beneficial to Cr(VI) reduction. Moreover, the possible reduction pathway of Cr(VI) to Cr(III) over the urea-derived g-C3N4 was proposed and the reduction process was mainly initiated by a direct reduction of photogenerated electrons.

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