Abstract
Natural adsorbents are a good alternative to remove antibiotic residues from wastewater. In this study, the adsorption capacity of sulfamethoxazole (SMX) onto sugarcane bagasse (SB) and corn cob (CC) in a continuous fixed-bed was compared. Brunauer Emmett Teller, Fourier transform infrared (FTIR), Boehm titration, and point of zero charge (pHpzc) were used to characterize both adsorbents. The adsorption capacity (qe) and the removal percentage of SMX (% R) were investigated at different different flow rates (2, 5, and 7 mL min− 1) and adsorbent masses (4 and 6.4 g), and a constant initial concentration of 5 mg L− 1. The results of the characterization showed that SB has a morphology with more dispersed particles and a specific surface higher than CC (2.6 > 1.2 m2 g− 1). Boehm titration indicates that both the surface of SB and CC have a greater amount of acid groups, which is in agreement with FTIR and pHpzc results. The continuous fixed-bed experiments showed that % R and qe of SMX are higher with SB in all the tests. The highest qe and maximum % R was 0.24 mg g− 1 and 74% with SB, and 0.15 mg g− 1 and 65% using CC. In most cases, the qe of both adsorbents decreased with the increase of flow rate and bed height. An analysis suggests that hydrogen bonds could be the main factor favoring the SMX adsorption with SB. Finally, the intraparticle diffusion was the rate-controlling step, predominating the pore-volume diffusion resistance.
Highlights
Antibiotics are widely used in humans and animals to fight diseases caused by bacteria
Penafiel et al [17] reported a pHpzc value of 5.9 for sugarcane bagasse (SB) from Ecuador; this indicates that the pHpzc for this biosorbent is around 6, which means that SB has almost null surface charge at pH of SMX solutions
These results are in accordance with those reported by Vera et al [22]
Summary
Antibiotics are widely used in humans and animals to fight diseases caused by bacteria. In animals, they have been used to a great extent to promote their growth and for the prophylaxis of diseases. They have been used to a great extent to promote their growth and for the prophylaxis of diseases After administration, they are partially metabolized, and a significant portion of the antibiotic can be excreted in the urine or feces as the parent compound or in conjugated forms. It has been estimated that between 70 and 90% of antibiotics administered in animals are excreted through urine and feces [1] As a result, these residues of antibiotics and their metabolites are released into the environment. Residual antibiotics for human and animal use can enter the environment through several pathways, including domestic and hospital wastewaters discharge, leaching, and runoff from land to which animal wastes with antibiotics have been applied [2]
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