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

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

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