Removal of Copper(II) Ions from Aqueous Solutions by Hydroxyapatite-Based Materials Prepared from Eggshells

Abstract

The experimental study aimed to establish the potential applications of the nano- and micrometric powders of hydroxyapatite in the removal processes of Cu(II) ions from synthetic aqueous solutions. For this purpose, hydroxyapatite (HAP) was used in the form of: 1) nanometric powder (labeled nano-HAP), and 2) calcium alginate hydroxyapatite composite microparticles (nicro-HAP-CaAlg). Eggshells have been used as a raw material to obtain HAP. The contact time, pH and Cu(II) concentration in the initial solution have been the main process variables with influence on the Cu(II) ions removal by HAP samples. For both HAP based materials, an optimal pH value of 5 has been established. The nano-HAP powder has a higher Cu(II) adsorption capacity than micro-HAP-CaAlg based on the specific surface area values of nano- and micrometric powders. The adsorption isotherm experiments showed that this process can be described using Langmuir model according to which the adsorption takes place as a monolayer process on an homogeneous surface. The kinetic study revealed that the sorption process of Cu(II) from synthetic aqueous solutions can be described using the pseudo-second order kinetics model according to which the rate-determining step is chemisorption. The values of the retention capacity recommends both powders tested (nano-HAP and micro-HAP-CaAlg) to be used in the Cu(II) loaded water treatment process.

Modeling of Solid-Fluid non-catalytic Processes for Nickel Ion Removal

“…The presence of heavy metals in the industrial wastewater has a serious environmental impact over aquatic life and humans. It is unanimous accepted that heavy metals and dyes has a strong impact on the environment [3][4][5][6][7][8].…”

An Overview of Synthesis Based Biomedical Applications of Hydroxyapatite Nanomaterials

“…Biomedical applications of HAp Due to biocompatibility, osteoconductivity, porosity, and similar chemical composition to the natural bones, HAp largely finds biomedical applications especially in dental applications, bone substitution and filling, tissue engineering, drug delivery systems etc. [21,71,72]. Some important biomedical applications of HAp reviewed in this section are illustrated in Scheme 2.…”

“…[6] https://www.nepjol.info/index.php/JNCS Incorporation of dual bioactive ions into nano-HAp particles produces biomaterials with improved bioactivities and osteo-conduction applicable for line cell imaging [20]. Nano-sized HAp better improves cytophilicity and possesses greater bioactivities, biosorption and proliferation to bone marrow optimizing biological functionality if compared to conventional micro/macro-sized HAp [19,21,22]. Similarly, crystalline HAp provides a comparatively suitable substrate to mesenchymal cells of bone marrow in terms of their adhesion, proliferation, and differentiation to osteoblasts than amorphous HAp even with their comparable size [23].…”