“…On increasing the pH, the removal efficiency increases owing to the increase in the negative charge density created on the surface, which in turn results in an electrostatic attraction between the SiO 2 /PANI–SDS surface and the positively charged MB molecules. Given these results, it seems that the electrostatic interaction taking place between the SiO 2 /PANI–SDS surface and the MB molecules over the entire investigated range of pH (3–12) is playing a predominant role in the adsorption process 32 . Figure 9 ( a ) The removal efficiency of MB at variable pH.…”
Natural resources including sand are one of the best approaches for treating dye-polluted wastewater. The SiO2/PANI-SDS nanocomposite was synthesized by self-assembly and intermolecular interaction. The physicochemical features of the SiO2/PANI-SDS nanocomposite were explored by FT-IR, XRD, SEM, TEM, EDX, and N2 adsorption–desorption techniques to be evaluated as an adsorbent for the MB. The surface area of the SiO2/PANI-SDS is 23.317 m2/g, the pore size is 0.036 cm3/g, and the pore radius is 1.91 nm. Batch kinetic studies at different initial adsorbate, adsorbent and NaCl concentrations, and temperatures showed excellent pseudo-second-order. Several isotherm models were applied to evaluate the MB adsorption on the SiO2/PANI-SDS nanocomposite. According to R2 values the isotherm models were fitted in the following order: Langmuir > Dubinin–Radushkevich (D–R) > Freundlich. The adsorption/desorption process showed good reusability of the SiO2/PANI-SDS nanocomposite.
“…On increasing the pH, the removal efficiency increases owing to the increase in the negative charge density created on the surface, which in turn results in an electrostatic attraction between the SiO 2 /PANI–SDS surface and the positively charged MB molecules. Given these results, it seems that the electrostatic interaction taking place between the SiO 2 /PANI–SDS surface and the MB molecules over the entire investigated range of pH (3–12) is playing a predominant role in the adsorption process 32 . Figure 9 ( a ) The removal efficiency of MB at variable pH.…”
Natural resources including sand are one of the best approaches for treating dye-polluted wastewater. The SiO2/PANI-SDS nanocomposite was synthesized by self-assembly and intermolecular interaction. The physicochemical features of the SiO2/PANI-SDS nanocomposite were explored by FT-IR, XRD, SEM, TEM, EDX, and N2 adsorption–desorption techniques to be evaluated as an adsorbent for the MB. The surface area of the SiO2/PANI-SDS is 23.317 m2/g, the pore size is 0.036 cm3/g, and the pore radius is 1.91 nm. Batch kinetic studies at different initial adsorbate, adsorbent and NaCl concentrations, and temperatures showed excellent pseudo-second-order. Several isotherm models were applied to evaluate the MB adsorption on the SiO2/PANI-SDS nanocomposite. According to R2 values the isotherm models were fitted in the following order: Langmuir > Dubinin–Radushkevich (D–R) > Freundlich. The adsorption/desorption process showed good reusability of the SiO2/PANI-SDS nanocomposite.
“…When the energy generated by external visible light is greater than the band gap width (Eg) of ZnO (Eg = 3.2 eV) and WO 3 (Eg = 2.7 eV), the photogenerated electrons in ZnO and WO 3 valence bands would be excited and jump to the conduction band, and a large number of holes would be generated in ZnO and WO 3 valence bands. Because the conduction potential of WO 3 is higher than that of ZnO, and the valence potential of ZnO is lower than that of WO 3 , when ZnO and WO 3 are in contact with each other, heterojunction is formed in the interface region of contact [35]. Under the action of potential gradients and the internal electric field, the excited photogenerated electrons transfer from the surface of ZnO to WO 3 conduction band, and finally a large number of photogenerated electrons accumulate in the WO 3 conduction band.…”
Semiconductor photocatalysis technology is an environmentally friendly and efficient emerging technology. This method can use sunlight as a driving force to quickly decompose organic pollutants in water bodies. Zinc oxide (ZnO) and tungsten oxide (WO3) photocatalysts can absorb sunlight and participate in photocatalytic degradation reactions due to their relatively narrow band gap. Highly photosensitive WO3 nanofibers and ZnO/WO3 composite nanofibers were fabricated via the electrospinning method. When 100 mg/L of rhodamine B (Rh B) solution was used as the degradation substrate, the degradation efficiencies of WO3 and ZnO/WO3 for Rh B dye were 70% and 90%, respectively, after a photocatalytic reaction of 120 min. The surface morphology, crystal structure, and optical properties of ZnO/WO3 composite nanofibers and WO3 nanofibers were characterized by SEM, XRD, XPS, and UV-vis absorption spectra, and the experimental results were analyzed and explained using different mechanisms. The results show that ZnO/WO3 composite nanofibers have better UV-visible light absorption performance, and the sample has a higher UV-visible light utilization rate. This was mainly due to the fact that a P-N heterojunction was formed in the semiconductor composite, and the electron–hole pair could realize rapid separation under the drive of a built-in electric field force, which promoted the migration of carrier. Therefore, the photocatalytic activity of the ZnO/WO3 catalyst was significantly higher than that of the WO3 catalyst, which promoted rapid improvement of the photocatalytic degradation efficiency of the Rh B dye.
“…The lumpy nature of sepiolite makes it difficult to separate from the aqueous phases and hinders subsequent processes for recovery and reuse [12]. Organic modification [13], pillared treatment [14], and acid activation [15] are some methods used to improve natural clay's adsorption performance.…”
Foam concrete is one of the most valuable porous materials used in civil and industrial buildings. Sepiolite, a fibrous hydrous magnesium silicate, possesses exceptional qualities such as a low thermal conductivity, non-polluting nature, and eco-friendliness. In this paper, a multi-functional sepiolite-based foam concrete has been fabricated using a physical foaming technology. The high sepiolite content and unique hierarchical structure endow the foam concrete with excellent adsorption and thermal insulation properties. The foam concrete exhibits a high adsorption capacity towards methanal and ammonia gases. Furthermore, the foam concrete, with its high porosity and good forming ability, shows great potential for application in thermal-insulation materials and wastewater treatment.
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