Removal of Nitrate Ions Using Thermally and Chemically Modified Bioadsorbents

Applied Sciences

Ángel Darío Gonzalez-Delgado¹  Ángel Villabona-Ortíz²  Candelaria Tejada-Tovar² 

[1] Nanomaterials and Computer-Aided Process Engineering Research Group (NIPAC), Chemical Engineering Department, University of Cartagena, Avenida del Consulado St. 30, Cartagena de Indias 130015, Colombia;Process Design and Biomass Utilization Research Group (IDAB), Chemical Engineering Department, University of Cartagena, Avenida del Consulado St. 30, Cartagena de Indias 130015, Colombia;

关键词: adsorption;    kinetics;    isotherms;    nitrate;    yam;   

DOI  :  10.3390/app11188455

来源: DOAJ

【 摘 要 】

Nitrate ions are one of the causes of surface water eutrophication. In the present research, the effective adsorption of nitrate ions (NO₃) on bioadsorbents prepared from yam skins (Dioscorea alata) was evaluated. The yam skin was chemically modified with ammonium chloride (NH₄Cl), and biochar was prepared from the thermally modified biomass. The results were compared with commercial coal (CC). The bioadsorbents were characterized by SEM-EDS analysis, which showed that the synthesized adsorbents have a heterogeneous surface with pores. The batch adsorption tests showed that the pH has the most significant effect on the NO₃ adsorption capacity when using the modified yam skin (MYP), obtaining as best conditions pH 12 and a 0.5 mm particle size with an adsorption capacity of 25.75 mg/g; the best adsorption capacity when using the carbon synthesized from yam skin (CYP) and CC was obtained at pH 2, reaching values of 36 and 33.34 mg/g, respectively. The following performance in terms of adsorption capacity was found: CYP > CC > MYP, according to Langmuir’s model. The equilibrium isotherm of NO₃ adsorption on MYP and CYP was adjusted by the Freundlich model, while the Langmuir model described adsorption on CC. The kinetics of all the systems studied showed a good fit to the pseudo-first-order, pseudo-second-order and Elovich models with R² > 0.95, suggesting a mechanism of chemical adsorption by means of species exchange between the aqueous phase and the surface of the material, with the intervention of an intraparticle diffusion stage; based on these findings, the studied biomasses reached promising adsorption capacities in the removal of nitrate anions, showing that the carbon synthesized from yam skins and modified with ammonium chloride had a remarkable behavior in comparison with commercial carbon and NH₄Cl-modified yam skins.

【 授权许可】

Unknown