Abstract
Human hair is considered a ubiquitous waste product and its accumulation can cause environmental problems. Hence, the search for alternatives that take advantage of this waste as a new raw material is of interest, and contributes to the idea of the circular economy. In this study, chemically modified human hair was used as a low cost biosorbent for the removal of heavy metal ions from aqueous solutions. The effect of the contact time, the pH, and the biosorbent concentration on the biosorption process were investigated. Kinetic modeling indicated that the pseudo-second order kinetic equation fitted well with R2 > 0.999. Furthermore, the equilibrium data fitted the Langmuir adsorption isotherm at 295 K resulting in saturation concentrations of 9.47 × 10−5, 5.57 × 10−5, 3.77 × 10−5, and 3.61 × 10−5 mol/g for the sorption of Cr(III), Cu(II), Cd(II), and Pb(II), respectively. The biosorption process did not change the chemical structure and morphology of the hair, which was shown by FTIR and SEM. In addition, desorption experiments prove that 0.1 mol/L EDTA solution is an efficient eluent for the recovery of Pb(II) from the treated human hair. To summarize, treated human hair showed satisfactory biosorption capacity and can be considered as an effective biosorbent for the treatment of water with a low concentration of heavy metal ions.
Highlights
Heavy metal ions are considered extremely harmful to humans, aquatic organisms, and other life forms because of their toxicity, accumulation, and non-biodegradable nature, causing various diseases and disorders [1]
The second step corresponds to a gradual biosorption uptake of heavy metal ions until reaching an equilibrium
The results show that the metal removal percentages of the regenerated hair samples are dependent on the elution methods
Summary
Heavy metal ions are considered extremely harmful to humans, aquatic organisms, and other life forms because of their toxicity, accumulation, and non-biodegradable nature, causing various diseases and disorders [1]. The presence of carboxyl, amido, and disulfide groups in human hair suggest this waste product could be a good biosorbent of several chemicals, including heavy metals, it has been rarely studied for this application [11]. In this regard, one of the major drawbacks is that its hydrophobic nature in native form limits the diffusion of heavy metal ions from the solution to the external surface of the human hair [22]. A desorption/regeneration test was performed in order to study the reusability of the biosorbent
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