Production of surfactant-modified banana peel biosorbents applied to treatment and decolorization of effluents

Abstract

In this study, banana peels (BP) were pretreated under different conditions and modified with surfactants cetyltrimethylammonium bromide (CTAB), dodecyl trimethylammonium bromide (DTAB), or sodium dodecyl sulfate (SDS). The biosorbents were used for the removal of the anionic Direct Blue 86 (DB86) from synthetic solutions as well as for the treatment of a textile effluent. The biosorbents were characterized by Fourier Transform Infrared Spectroscopy (FTIR), contact angle measurements, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and point of zero charge (pHPZC). The results showed that the pretreatment using natural oxidation of BP showed better adsorbent performance than other pretreatments at pH 2. Treatment with SDS did not improve the sorption efficiency of the material. The biosorbents modified with DTAB (B-DTAB) and CTAB (B-CTAB) showed good performance with a maximum dye removal of 96.2% (at pH 2) and 91.7% (at pH 6), respectively, using 1.00 g L−1 of the biosorbents, constant stirring of 150 rpm for 60 min at 25 °C, and DB86 concentration of 10.0 mg L−1. The kinetics of B-DTAB and B-CTAB showed the best fit to the pseudo-first and pseudo-second-order models, respectively. The intraparticle diffusion model suggested that adsorption on B-CTAB may be guided by pore and film diffusion. Sips isotherm was found to be the best fit with theoretical maximum adsorption capacities from non-linear fit of 25.2 and 147 mg g−1, respectively, for B-DTAB and B-CTAB (1.00 g L−1 of the biosorbents, constant stirring of 150 rpm, 25 °C, and initial pH 6). Results suggest that mainly precipitation, hydrophobic interactions, and electrostatic attraction drives the sorption process. The treatment of the textile effluent using B-CTAB resulted in a reduction of 60.6% in color and 53.2% in effluent turbidity, demonstrating the potential of modified banana peels as promising biosorbents for environmental applications.