Hybrid carbon materials:synthesis, characterization, and application in the removal of pharmaceuticals from water

Abstract Hydrothermal carbonization was used to develop novel carbon-based hybrids for the removal of diclofenac and amoxicillin from water. These non-crystalline and partly graphitic materials can be regenerated by photocatalysis. The synthesized materials have beneficial oxygen containing surface functional groups, of which C=O were observed only for tungsten-containing hybrid. An interaction between W, C and TiO₂ was observed, which could influence the photocatalytic performance. The best performance was observed for W-containing hybrid (HC butox W) at pH 3 (diclofenac photocatalytic degradation of 80% and removal of 93% after 60 min). Significant part of the removal appeared due to precipitation of diclofenac on the hybrid material surface. Removal efficiency was fully recovered after regeneration at pH 7 under uv-B irradiation. With the same hybrid, 10% removal of amoxicillin after 30 min with 42% photocatalytic degradation at non-adjusted pH was reached. In general, tungsten improved the photocatalytic activity of material, while specific surface area played only a minor role

Porous foams based hydroxyapatite prepared by direct foaming method using egg white as a pore promoter

Abstract Stoichiometric hydroxyapatite (Ca₁₀(PO)₆(OH)₂, HAP) foams have been produced. The porous parts were prepared from a calcined HAP powder and egg white as a bio and non-toxic pore promoter. The colloidal slurry was prepared, poured into cylindrical molds, dried, unmolded, and sintered at 1200 °C. The effects of the concentration of the solid loading, of the dispersing agent, and the foaming agent on the ceramic preparation were examined. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were used to evaluate the composition and the structure of the sintered HAP ceramics. Scanning electron microscopy (SEM) was used for microstructural analysis. The XRD analysis of the porous parts, prepared under optimized conditions, showed the presence of crystallized HAP (JCPDS 9-432) as a single phase. SEM images showed existence of open and interconnected micro and macropores in the ceramics. The use of the egg white protein as pore former provides a total porosity of 86 vol% and a foam-structure that allows to a microporous wall

Ceramic hydroxyapatite foam as a new material for Bisphenol A removal from contaminated water

Abstract Ceramic hydroxyapatite foam (CF-HAP) was prepared by combining slip-casting and foaming methods. The prepared CF-HAP was characterized by scanning electron microscopy (SEM), physisorption of N2, Fourier transforms infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results of the specific surface area and SEM analyses revealed that the used shaping method provides CF-HAP with a wide range of porosity including macro and mesopores. Based on FTIR and XRD analyses, the CF-HAP is similar to pure well-crystallized hydroxyapatite. The adsorption results revealed that 94% of the BPA with a concentration of (40 mg/L) was effectively removed from the water and that the maximum adsorption capacity was higher in acidic than in basic medium. The thermodynamic studies indicated that the adsorption reaction was spontaneous and endothermic in nature. The adsorption capacity increased with the temperature and the BPA is chemisorbed on the ceramic foam. The isotherm data fitted slightly better with the Liu than with the Freundlich and Langmuir models suggesting that the adsorption was homogeneous and occurred only in the monolayer. The adsorption process depends largely on the BPA concentration and the results fitted well with the pseudo-first-order model. This confirms that the interaction between the BPA and the CF-HAP was mainly chemical in nature. The FTIR analysis of the used and fresh CF-HAP showed that all the hydroxyl and phosphorus bands characteristic of the hydroxyapatite shifted after adsorption of Bisphenol A. This suggests that the adsorption of Bisphenol A occurred in the sites of the hydroxyapatite. Therefore, it can be concluded that the CF-HAP has the potential to be used as an adsorbent for wastewater treatment and purification processes

Development and characterization of composite carbon adsorbents with photocatalytic regeneration ability:application to diclofenac removal from water

Abstract This paper presents results related to the development of a carbon composite intended for water purification. The aim was to develop an adsorbent that could be regenerated using light leading to complete degradation of pollutants and avoiding the secondary pollution caused by regeneration. The composites were prepared by hydrothermal carbonization of palm kernel shells, TiO₂, and W followed by activation at 400 °C under N₂ flow. To evaluate the regeneration using light, photocatalytic experiments were carried out under UV-A, UV-B, and visible lights. The materials were thoroughly characterized, and their performance was evaluated for diclofenac removal. A maximum of 74% removal was observed with the composite containing TiO₂, carbon, and W (HCP25W) under UV-B irradiation and non-adjusted pH (~5). Almost similar results were observed for the material that did not contain tungsten. The best results using visible light were achieved with HCP25W providing 24% removal of diclofenac, demonstrating the effect of W in the composite. Both the composites had significant amounts of oxygen-containing functional groups. The specific surface area of HCP25W was about 3 m²g⁻¹, while for HCP25, it was 160 m²g⁻¹. Increasing the specific surface area using a higher activation temperature (600 °C) adversely affected diclofenac removal due to the loss of the surface functional groups. Regeneration of the composite under UV-B light led to a complete recovery of the adsorption capacity. These results show that TiO₂- and W-containing carbon composites are interesting materials for water treatment and they could be regenerated using photocatalysis

Structured carbon foam derived from waste biomass:application to endocrine disruptor adsorption

Abstract In this paper, a novel structured carbon foam has been prepared from argan nut shell (ANS) was developed and applied in bisphenol A (BPA) removal from water. The results showed that the prepared carbon foam remove 93% of BPA (60 mg/L). The BPA equilibrium data obeyed the Liu isotherm, displaying a maximum uptake capacity of 323.0 mg/g at 20 °C. The calculated free enthalpy change (∆H° = − 4.8 kJ/mol) indicated the existence of physical adsorption between BPA and carbon foam. Avrami kinetic model was able to explain the experimental results. From the regeneration tests, we conclude that the prepared carbon foam has a good potential to be used as an economic and efficient adsorbent for BPA removal from contaminated water. Based on these results and the fact that the developed structured carbon foam is very easy to separate from treated water, it can serve as an interesting material for real water treatment applications