Abstract
In the present investigation, results obtained from the process of the biosorption of Zn(II) in synthetic wastewaters are presented, using three agricultural wastes (coffee pulp, banana pseudo-stem, and corncob). Firstly, the percentage of lignin and cellulose for each material was determined. Then, using the free software XLSTAT, the waste with the highest removal for this metal was selected and, after this, the optimum pH, kinetics, adsorption isotherm, and point of zero charge (pHpzc) were found. Finally, a comparison with other lignocellulosic materials derived from banana, corn, and coffee crops was carried out. According to the results obtained, coffee pulp was the material that showed a high removal compared to the other two (63.58%), for which the optimum pH was 5.0 units. The kinetic model, which was adjusted to the process of biosorption, was the pseudo second order of Ho and McKay, which in turn presented an isotherm of Langmuir’s linearized model where the maximum adsorption capacity with that waste was 13.53 mg × g−1, obtained with a particle size of 180 µm, contact time of 90 min at 100 RPM, temperature of 25 °C, and pHpzc 3.95 units. Lastly, the authors state that this type of agricultural waste can be used as a green technology in the treatment of wastewater, particularly in the removal of the aforementioned pollutant, in order to fulfill goals 3.9 and 6.9 of the Sustainable Development Goals of the 2030 Agenda; to the level of challenge of the research, the authors propose for the future to carry out the implementation of this type of waste, without chemical modification, in the treatment of wastewater for the removal of the mentioned pollutant in a pilot study with different wastewaters and industries.
Highlights
The World Health Organization (WHO) has cataloged thirteen heavy metals as toxic, among which is Zn [1]
At the level of the adsorption parameters, we obtained that the optimum pH for the removal of
The kinetic adsorption model that was the best adjusted was that of the pseudo second order of Ho and McKay, with an isotherm of Langmuir’s linearized
Summary
The World Health Organization (WHO) has cataloged thirteen heavy metals as toxic, among which is Zn [1]. This metal, of atomic number 30, with oxidation states −2, 0, +1, +2, and +3 [2,3], has multiple applications at the industrial and laboratory level, among which are car parts, electronic equipment, light machine tools, metal coating, glass manufacturing, matches, glues, paint manufacturing, varnishes, ceramics, medications, sunscreen, deodorants, electrodeposition, toys, and batteries [4,5]. In the wastewater discharge generated in industrial processes that incorporates said metal, its final disposal is carried out without a treatment process, which can affect surface water sources or supply areas for a certain population, as well as the ecosystem. In the case of Colombia, the regulations that apply to wastewater discharge correspond to Resolution 631 of 2015 of the Environment and Sustainable
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