Synthesis of hydroxyapatite from mussel shells for effective adsorption of aqueous Cd(II)

Abstract

We report the synthesis of hydroxyapatite (HAP) powder from waste mussel shells (decomposed to CaO) and phosphoric acid at room temperature without pH control. The powder synthesized was utilized for cadmium removal from aqueous solutions using the batch technique. The effects of solution pH, adsorbent dose; initial Cd2+ concentration, contact time, and temperatures were examined. Furthermore, the adsorption process revealed a pseudo-second-order reaction model and the Langmuir isotherm is the best-fit model to predict the experimental data and adsorption capacity was found to be 62.5 mg/g. Thermodynamic analysis revealed that because of the negative values of ΔGo and the positive value of ΔHo, the adsorption process was spontaneous and endothermic. Cadmium immobilization occurs through a two step mechanism: rapid ion exchange followed by partial dissolution of hydroxapatite and precipitation of cadmium containing hydroxyapatite.

An insight into the structure, composition and hardness of a biological material: the shell of freshwater mussels

“…[32][33][34][35][36][37][38] While discarded marine shells derived from mussels, oysters, clams and abalones have been characterized as biological material with multiple utility, few efforts have been made from the freshwater mussels. 41,54 Several studies have shown that shells of marine bivalves and gastropods are more worthy as waste with multiple applications in the eld of biodiesel production, 39,40 waste water treatment, 46,47 soil amelioration, [48][49][50] biosorbent for dye and heavy metal, 45,51,52,54,55 llers and alternative to mortars, 56,57 and as an alternative to the bone materials. 32 In order to judge and qualify the shells of freshwater mussels as a biological material with potential for multiple applications in agriculture and industry, characterization of the shell at the physical and chemical levels is a pre-requisite.…”

“…50 The shells of the mussels and snails are cost effective biosorbent that can be used for the purpose of metal and dye removal, 36,51,52 directly as akes or granules 53,54 or through the formation of hydroxyapatite. 55 The shells of the bivalves are also considered suitable as llers and for the use as a substitute to mortar. 56,57 Owing to the diverse applications ranging from the water purication to the soil amelioration, the shells of mussels, oysters and clams are true aquaculture waste with considerable value to safeguard ecology and mobilize economy.…”

A Comparative Study on Hexavalent Chromium Adsorption onto Chitosan and Chitosan-Based Composites

“…A study on natural and synthetic apatite has been produced to evaluate their heavy metals and organic substances adsorption capacities through the improvement of its textural properties such as specific surface area, porosity, and active sites [ 13 ]. Studies have shown an interest in fixing various types of molecules (polymer, acid, organic matter) on the apatite matrix, especially to hydroxyapatite (Hap) [ 14 , 15 ]. Hydroxyapatite is a biocompatible material with low water solubility, chemical stability, and excellent buffering capacity [ 16 ], while Cs is a chelating polycationic polymer, known for its non-toxicity, biocompatibility, and biodegradability.…”

Adsorption Mechanism of Bentonite with Dispersed Chitosan for Cadmium Ions

“…Some agricultural waste materials were modified through grafting or pyrolysis to improve their adsorption capacities 7, 8. Likewise, molecular sieves 9, ceramsite 10, hydroxyapatite 11, activated carbon 12, metal‐organic frameworks (MOFs) 13, 14, graphene 15, and other materials were functionalized or modified for the removal of Cd 2+ . However, as reported by many research groups 16, 17, cadmium ions seem to be more difficult to remove with the same adsorbent compared to another typical heavy metal Pb 2+ ion, regardless of the basis of mole or mass for comparison.…”