Abstract

In this work, the removal of the hazardous Ponceau S dye (PS) from aqueous solutions was investigated using Fish Scale (FS) of Sardina pilchardus as low-cost adsorbent. Different relevant factors such as contact time, initial pH, initial PS concentration, biosorbent dose and temperature were examined to evaluate their effects. The optimization of these factors was performed with a Central Composite Design (CCD). Optimized parameters (pH = 2.1, [PS] = 35 mg L−1, m(FS) = 250.0 mg, V = 200 mL and T = 303 K) were found with the maximum of 96.58% PS loading onto FS. The kinetics results show that the pseudo-first-order model gave a better fit than the pseudo-second-order model. Freundlich isotherm gave a better fit than Langmuir model. The thermodynamic factors, such as Gibb’s free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) have been calculated. The biosorption was found to be a spontaneous and endothermic process. The desorption of PS from exhausted biosorbent was investigated in alkaline solution. Furthermore, Monte Carlo (MC) and radial distribution function (RDF) simulations were achieved to obtain a better understanding of biosorption mechanism of PS on both collagen and hydroxyapatite (HDA) which are the main constituents of FS. The results showed that PS presented a better biosorption on collagen than on the HDA surface. The biosorption of PS onto studied surfaces was spontaneous, characterized highly by chemical interactions and slightly by physical ones. Since FS is a low-cost marine waste, it presents interesting perspectives in the treatment of contaminated wastewaters on a large-scale.

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