The prevalence of organic dyes contamination in water has driven widespread research on developing effective treatment systems including adsorption using various sorbents. The aim of this study is to investigate the methylene Blue (MB) adsorption of Diatomite Phu Yen and the influence of Fe loading into adsorption capacity. The prepared samples were characterized by XRD, TEM, EDX and BET methods to examine their structural, morphological properties, elemental composition and surface characteristics. Bath adsorption isotherms are conducted at several temperatures (283, 293, 303 and 313K).The data sets are analyzed with Langmuir and Freundlich models which produce Langmuir and Freundlich equilibrium constants (KL, KF), of adsorption for each process. Adsorption kinetics are followed closely the pseudo-second order model. The obtained results show that Diatomite could be an efficient adsorpbent for the removel of organic dyes from polluted environment. The presence of Fe results in negative MB adsorption behavior.

The adsorption and activation processes of CO2 and H2 on Ni5 catalyst supported on activated carbon (Ni5/AC) were investigated by using density functional theory at GGA-PBE/DZP level of theory and climbing image – nudged elastic band (CI-NEB) method. The adsorption energy, charges on atoms, bond orders and geometry parameters were calculated and analyzed. The most favourable adsorption configurations were determined. The results show that H2 and CO2 are chemically adsorbed on Ni5/AC. The adsorption process does not involved a transition state. CO2 is strongly activated on Ni5/AC system.

A robust and accurate tight-binding quantum chemical method (GFN2-xTB) was performed to study the electronic and optical properties of graphitic carbon nitride (g-C3N4) and g-C3N4 modified with non-metal atom (B, C, N, O, F). The vertical ionization potential, electron affinity and global electrophilicity indexes were calculated and analyzed. The obtained results show that the doping of B, C, N, O or F atom onto the surface g-C3N4 is favorable in terms of formation energy. The introduction of non-metal atoms raises the Lewis acidity of g-C3N4. The calculated UV-VIS spectra show that the doping of non-metal atoms increases the absorption intensity of visible light compared to the pure g-C3N4.

The methanation of carbon dioxide over Ni5 supported on activated carbon (Ni5/AC) was studied by using density functional theory and climbing image – nudged elastic band methods. A reaction diagram for the formation of methane via CO or HCOO species, which consists of 14 reaction steps was proposed. The reaction energy and activation energy for the overall steps involved in the reaction process were calculated and analyzed. Following the proposed mechanism possible carbon byproducts of the CO2 methanation reaction are CO and HCHO. Formation of these products can occur at high temperatures, but it is more thermodynamically difficult than formation of CH4. The formation of CH4 is more preferably occur via the CO pathway than the HCOO pathway.

Nanoflower MoS2, nanowire TiO2(NNW) and 3D MoS2/TiO2 nano-heterostructure have been synthesized successfully by simple typical hydrothermal reaction method followed by 200oC calcination under an argon atmosphere. The prepared samples are characterized in detail by XRD, FESEM, UV-vis DRS, EDX and BET. The results suggest that the TiO2 NNWis successfully coupled with MoS2 to form the heterojunction nanostructure. The hybrid heterostructures can effectively utilize visible-light and solar energy to degrade 2,4-dichlorophenoxyacetic acid (2,4-D). The degradation rate of 2,4-D is as high as 99%. The improved photocatalytic activity owes to the decreased band-gap and the heterosurface properties of MoS2/TiO2, promoting the electron-hole pairs separation and absorption capacity to visible light. This work presents a facile approach for fabricating the MoS2/TiO2 heterostructures for efficient photocatalytic 2,4-D solution, which will facilitate the development of designing photo catalysts applied in environment and energy.