Abstract
The ongoing process of urbanization in China has led to a growing concern regarding environmental contamination caused by the significant accumulation of construction demolition trash. This study employs the water thermal method to synthesize hydroxyapatite using natural waste oyster shells as the primary raw material. This study explores the use of synthesized hydroxyapatite (O-HA) on building waste red-brick fragments (RBF) for removing cadmium (Cd(II)) and chromium (Cr(VI)) from water. The RBF fillers, both before and after modification, underwent comprehensive characterization using various techniques, including automated analysis of specific surface area and porosity (BET), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). In the sixth cycle of purification experiments, the average removal rate of Cd(II) by O-HA-modified red-bricks (O-HA/RBF) could still reach 88.18 %, which was about 20.00 % higher than that of the RBF. However, the removal of Cr(VI) by O-HA/RBF was unsatisfactory at 5.33 %. The adsorption mechanisms of Cd(II) and Cr(VI) were explored by isothermal adsorption tests and adsorption kinetic tests. According to the mechanism analysis, physical adsorption and chemical adsorption were the main reasons for Cd(II) adsorption by O-HA/RBF. This involves ion exchange and surface complexation between calcium ions in O-HA and Cd(II), forming a low-solubility precipitate for effective removal. However, for Cr(VI), physisorption predominantly governs O-HA/RBF, elucidating the limited efficacy in Cr(VI) removal. The cost analysis showed that using O-HA/RBF as filler reduced overall expenses in wetland development, offering promising prospects for engineering applications.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
