Effect of calcination temperature on the structure and performance of rod-like MnCeOx derived from MOFs catalysts

Effect of inorganic salt on the removal of typical pollutants in wastewater by RuO2/TiO2 via catalytic wet air oxidation

The treatment of high-salinity and high-organic wastewater is a tough task, with the removal of organic matter and the separation of salts often mutually restricting. Catalytic wet air oxidation (CWAO) coupled desalination technology (membrane distillation (MD), membrane bioreactor (MBR), ultrafiltration (UF), nanofiltration (NF), etc.) provides an effective method to simultaneously degrade the high-salinity (via desalination) and high-organic matters (via CWAO) in wastewater. In this work, five kinds of RuO₂/TiO₂ catalysts with different calcination temperatures were prepared for CWAO of maleic acid wastewater with a theoretical chemical oxygen demand (COD) value of 20,000 mg L^-1. RuO₂/TiO₂ series catalysts demonstrated prominent salt resistance, with more than 80% TOC removal rates in the CWAO system containing 5 wt% Na₂SO₄; while RuO₂/TiO₂-350 showed the best degradation performance in both non-salinity and Na₂SO₄-containing conditions. Multiple characterization techniques, such as XRD, BET, XPS, NH₃-TPD and TEM etc., verified the physicochemical structure of RuO₂/TiO₂ catalysts, and their influence on the degradation of pollutants. The calcination temperature was found to have a direct impact on the specific surface area, pore volume, oxygen vacancies and acid sites of catalysts, which in turn affected the ultimate catalytic activity. Furthermore, we also investigated the performance of the RuO₂/TiO₂-350 catalyst for the treatment of acids, alcohols and aromatic compounds with the addition of NaCl or Na₂SO₄, proving its good universality and excellent salt resistance in saline wastewater. Meanwhile, the relationship between the structure of three types of organic compounds and the degradation effect in the CWAO system was also explored.

Effect of Solvothermal Temperature on Morphology and Supercapacitor Performance of Ni-MOF

A series of Ni-MOF materials were synthesized via a simple hydrothermal method and can be employed as electrodes for supercapacitors (SCs). Different temperatures were selected to unveil the effect of temperature on the formation, structure, and electrochemical performance of Ni-MOF-x (x = 60, 80, 100, and 120). Ni-MOF-80 possessed a larger specific surface area with a cross-network structure formed on its surface. The synthesized Ni-MOF electrode delivered a specific capacity of 30.89 mA h g^-1 when the current density reached 1 A g^-1 in a three-electrode system. The as-fabricated Ni-MOF materials could be further designed and are expected to deliver satisfactory performance in practice.

Adsorption of paratoluic acid on MIL-53 (Al) metal-organic framework, and response surface methodology optimization

In this study, an organic metal framework adsorbent was used to remove paratoluic acid from aqueous solutions. The effect of various parameters such as pH, initial concentration of paravoluic acid, contact time, and amount of adsorbent was investigated by experimental design method. Central composite design (CCD) was used to optimize paratoluic acid uptake. Initially, MIL-53 (Al) was synthesized, and characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), spectroscopy, and thermogravimetry (TGA). The results of central composite design showed that pH is the most essential factor in the removal of paratoluic acid with MIL-53 (Al). The maximum removal efficiency of paratoluic acid by MIL-53 (Al) adsorbent is 93.67%, the optimal amount of adsorbent is 0.396 g, the optimal time is 35.67 min, the initial concentration is 11.12 mg L−1. The pH is 6.6 with the desired amount 1 is. Isothermal, and kinetic models have also examined. The maximum adsorption capacity was 132.05 (mg g−1), and the adsorption data of MIL-53 (Al) were well consistent with the quasi-second order, and Langmuir isotherm models.

A comprehensive review on water remediation using UiO-66 MOFs and their derivatives

Metal-organic frameworks (MOFs) are a versatile class of porous materials offering unprecedented scope for chemical and structural tunability. On account of their synthetic versatility, tunable and exceptional host-guest chemistry they are widely utilized in many prominent water remediation techniques. However, some of the MOFs present low structural stabilities specifically in aqueous and harsh chemical conditions which impedes their potential application in the field. Among the currently explored MOFs, UiO-66 exhibits structural robustness and has gained immense scientific popularity. Built with a zirconium-terephthalate framework, the strong Zr-O bond coordination contributes to its stability in aqueous, chemical, and thermal conditions. Moreover, other exceptional features such as high surface area and uniform pore size add to the grand arena of porous nanomaterials. As a result of its stable nature, UiO-66 offers relaxed admittance towards various functionalization, including synthetic and post-synthetic modifications. Consequently, the adsorptive properties of these highly stable frameworks have been modulated by the addition of various functionalities. Moreover, due to the presence of catalytically active sites, the use of UiO-66 has also been extended towards the degradation of pollutants. Furthermore, to solve the practical handling issues of the crystalline powdered forms, UiO-66 has been incorporated into various membrane supports. The incorporation of UiO-66 in various matrices has enhanced the rejection, permeate flux, and anti-fouling properties of membranes. The combination of such exceptional characteristics of UiO-66 MOF has expanded its scope in targeted purification techniques. Subsequently, this review highlights the role of UiO-66 in major water purification techniques such as adsorption, photocatalytic degradation, and membrane separation. This comprehensive review is expected to shed light on the existing developments and guide the inexhaustible futuristic scope of UiO-66 MOF.

Microwave-Assisted Hydrothermal Carbonization of Pomegranate Peels into Hydrochar for Environmental Applications

Several studies have reported that the hydrothermal carbonization method (HTC) of agricultural waste is able to produce a solid residue with interesting properties for the adsorption of organic pollutants from contaminated water. This work represents a facile method to prepare hydrochar (HC) from pomegranate peels’ waste using the microwave-assisted hydrothermal carbonization method (MHTC) at 200 °C for 1 h with a mass ratio of peel to water = 1:10. Activated hydrochar (AHC) was prepared by in situ chemical activation using ZnCl2 and MHTC. Several techniques have been applied to characterize the prepared samples as FTIR, XRD, TEM and SEM. The samples were investigated for their possible use as adsorbents of methylene blue (MB) dye. The results confirm the formation of amorphous hydrochar with a porous structure. The pH of zero point charge (pHzpc) is 4.3 and 4.6 for HC and AHC samples, respectively. The maximum adsorption capacity of HC and AHC samples are 194.9 and 12.55 mg/g (i.e., mg of adsorbate/g of adsorbent), respectively.

Low temperature curable titanium-based sols for visible light photocatalytic coatings for glass and polymeric substrates

Titanium oxide (TiO2) is a widely used material in photocatalytic coatings in which efficiency generally lies in the ultraviolet (UV) spectrum of light. Sol-gel method provides a simple and versatile...

Enhanced Cr(vi) removal by hierarchical CoFe2O4@SiO2–NH2via reduction and adsorption processes

CoFe2O4@SiO2–NH2 shows excellent removal performance towards Cr(vi) due to its excellent electrostatic effect as well as the reduction process originating from the –CH group.

Facile solvothermal assisted g-C3N4 post-grafting with aromatic amine dyes for effective photocatalytic hydrogen evolution

Dye grafted g-C3N4 using covalent bonds via a Schiff base chemical reaction exhibit much higher photocatalytic activity for H2 evolution.