Snail Shells Adsorbent for Copper Removal from Aqueous Solutions and the Production of Valuable Compounds

Abstract

This research explored the efficiency of snail shells powder (SSP) for Cu(II) removal from aqueous solutions and the production of valuable compounds from the residual product. To confirm its chemical and mineral components, the material was characterized by different instrumental techniques. The effects of experimental parameters such as the pH of the solution, the effect of SSP dose, particle size, and initial concentration of Cu(II) on the removal process were studied. The removal of Cu(II) was reasonably fast to be completed within a time frame of 90 min. The kinetics following the pseudo-second-order model (R2 = 0.979) were better compared to the pseudo-first-order model (R2 = 0.896). The increase in pH values leads to an increase in the amount of Cu(II) adsorbed. Afterward, the adsorption capacity reaches stability at pH near 7. The maximum Cu(II) removal occurred with a mass of 8 g·L−1 and a particle size of 300 μm. This particle size presents approximately 44.5% of SSP particles, which is the largest proportion of the sample as shown by particle size analysis. The adsorption isotherm was well described by Langmuir and Freundlich equations. The thermodynamic parameters values showed that the Cu(II) adsorption was a spontaneous and exothermic process. Furthermore, with the presence of CaCO3, the precipitation of Cu(II) in the form of posnjakite occurred with a high Cu(II) removal rate close to 99%. The residual SSP was used for the production of valuable compounds through the thermal decomposition process at various temperatures.

Synthesis of pure and doped nano-calcium phosphates using different conventional methods for biomedical applications: a review

“…After sintering at 700 1C, the predominant phase of CaCO 3 was calcite, while CuO and CaO were the secondary phases. 278,280 Each XRD pattern changed from 29.441 to 26.241 when heated from 105 to 700 1C. SEM analysis revealed large, irregular particles of HAp, with the finest measuring 26.9 mm and the largest, 322 mm.…”

A Critical Review of Snail Shell Material Modification for Applications in Wastewater Treatment

“…When the contact time increases, the adsorption efficiency increases as well, but after a certain threshold, the effect saturates and no longer increases. When investigating the influence range of 0 to 180 min, Redouane Ouaf et al found the highest Cu(II) removal efficiency at 90 min in a study on snail shells [ 109 ]. A study of Cd 2+ treatment at pH 6 over a survey period of 10 to 80 min found that treatment efficiency was lowest at 10 min and highest at 60 min.…”

“…In addition to the important influencing parameters listed above, some studies also evaluated the effect of different particle sizes and the ratio of admixture on adsorption efficiency or ionic strength on adsorption capacity. Specifically, in the study of Redouane Ouaf and colleagues, the different particle sizes were evaluated from 50 to 800 μm and the results showed that the effect of particle size on waste removal efficiency was not significant [ 109 ]. However, when comparing the effect, it is a good choice for the shell adsorbent for particle sizes larger than 300 μm.…”