Green coconut (Coco nucifera) biowaste: its conversion into a sustainable magnetic nanomodified biosorbent for dye removal

The present investigation aimed to study the adsorption potential of the endocarp (ED) and the mesocarp (MS) of green coconut (Coco nucifera) prior to and after nanomodification with magnetic nanoparticles (NP) to synthesize the nanocomposites ED-NP and MS-NP. These adsorbent materials were characterized by Fourier Transform Infrared (FTIR) and X-ray (XRD) spectroscopies, and Scanning Electron Microscopy (SEM), and used to treat dye-contaminated water. These analyses confirmed the effectiveness of the synthesis process of the coconut biomass nanocomposites with magnetite. The studies revealed that the best pH for MB sorption by ED-NP and MS-NP was 9.0. The kinetic model that best fit the experimental data was the pseudo-second-order type for both adsorbents (ED-NP and MS-NP), with equilibrium reaching within 60 min of adsorbate-adsorbent contact time. The maximum dye sorption capacity (Q_exp) for ED, ED-NP, MS, and MS-NP was 192.83 ± 7.91, 40.57 ± 0.48, 52.71 ± 1.76, and 67.01 ± 2.00 mg g⁻¹, respectively. The analysis of the salinity effect on the sorption process revealed that high salts concentration causes a loss of about 16% in the of MB Q_exp. Finally, all investigated materials presented a high potential for MB removal in water, even under high salinity conditions.