Alumina–Hydroxyapatite Millimetric Spheres for Cadmium(II) Removal in Aqueous Medium

Abstract

Heavy metals can act as selective agents in the development and proliferation of antibiotic-resistant bacteria through a process called coselection. In the year 2050, an estimated 10 million deaths will be caused by antibiotic-resistant bacteria; therefore, the presence of heavy metals in bodies of water represents an environmental and sanitary threat that requires efficient treatment processes and/or materials for their removal. In the present study, the effect of the hydroxyapatite coating on the adsorbent capacity of cadmium in alumina spheres was evaluated. The hydroxyapatite coating on the alumina sphere increased the surface area from 0.66 to 0.96 m2/g and the number of acid sites from 0.064 to 0.306 meq/g and displaced the IEP of hydroxyapatite from 5.37 to 4.2, increasing the Cd2+ adsorbing capacity from 59.87 mg/g to 89.37 mg/g and promoting adsorption by surface complexation. Alumina-hydroxyapatite spheres stand out for their improved adsorbent properties and easy handling, which positioned this material as a potential alternative in adsorption processes.

Silver Nanoparticles: Multifunctional Tool in Environmental Water Remediation

“…The toxic effects of releasing silver nanoparticles into the environment have been reported in different reviews [107,108]. Technologies for water remediation must present low or no secondary contamination; therefore, the use of silver nanoparticles as a tool in environmental water remediation must be limited or conditioned by the use of an innocuous support matrix (solid substrate) with high affinity to AgNps (e.g., hydroxyapatite) [12,109] to avoid their release into the environment or if the application or treatment involves the use of nanoparticles in suspension, it is recommended to use catchment traps of the same support material. The immobilization of AgNps on a substrate is a requirement for its applications at an industrial level as well as in situ, allowing its use safely and avoiding damage to the environment due to its release.…”