Elucidating the adsorption mechanism of Rhodamine B on mesoporous coconut coir-based biosorbents through a non-linear modeling and recycling approach

• Published in: Environmental science and pollution research international 2022-11, Vol.29 (53), p.79920-79934
• Main Authors: Nascimento, Rogério José Melo, Bezerra, Luiz Carlos Alves, Almeida, Jéssica Silva, de Oliveira Barros, Matheus, Silva, Lucas Renan Rocha, Rosa, Morsyleide Freitas, Mazzeto, Selma Elaine, Lomonaco, Diego, Pereira, Kilton Renan Alves, Avelino, Francisco
• Format: Article
• Language: English
• Subjects: Adsorbates; Adsorbents; Adsorption; Adsorption (and Catalysis or Photocatalysis) Applied to Environmental Protection; Adsorptivity; Agricultural wastes; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biorefineries; Cellulose; Cellulose - chemistry; Chemical modification; Cocos - chemistry; Desorption; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fibers; Hydrogen-Ion Concentration; Kinetics; Lignocellulose; Nitrogen; Reuse; Rhodamine; Waste Water Technology; Water Management; Water Pollutants, Chemical - analysis; Water Pollution Control
• ISSN: 0944-1344; 1614-7499; 1614-7499
• DOI: 10.1007/s11356-022-18808-9

The search for renewable adsorbent materials has increased continuously, being the agro-wastes an interesting alternative. This work aimed to elucidate the mechanism of adsorption of Rhodamine B on crude and modified coconut fibers from aqueous systems and the feasibility of reusing the biosorbents. The chemical modification of crude coconut fiber was carried out by the organosolv process. The biosorbents were characterized by lignocellulosic composition, FTIR, TGA, WCA, SEM, nitrogen adsorption/desorption (BET-BJH), and pH of zero point of charge (pH PZC ) analyses . The batch adsorption tests evaluated the effects of the adsorbent and adsorbate dosages, contact time, and temperature on Rhodamine B adsorption. For elucidating the adsorption mechanisms involved in the process, the non-linear forms of kinetic and isotherm models were used. The regeneration of the biosorbents was evaluated by carrying out the desorption experiments. Modified coconut fiber had an increase in the amount of α-cellulose, which influenced its structural, morphological, surface, and porous properties. The removal efficiency of Rhodamine B was about 90% for modified coconut fiber and 36% for crude coconut fiber. The dye adsorption was spontaneous and endothermic for both biosorbents, showing higher spontaneity and affinity with the adsorbate for biosorbent modified. Therefore, the coconut fiber can be considered an alternative to the traditional adsorbent materials that allows the reuse by four times without performance loss, in which its adsorptive capacity has increased through its chemical modification by a biorefinery process.