Evaluación de la adsorción de plomo (II) en soluciones acuosa utilizando como bioadsorbente la especie vegetal Brassica nigra

Currently, lead is one of the metals that has damaged different rivers of our country in recent years. Previously it is known that the family of the Brassica nigra has obtained good results in phytoremediation of polluted soils with heavy metals, with this research we seek to take advantage of its stem and root to remove lead from aqueous solutions. First, the biomass was characterized with FTIR analysis to identify the main functional groups, the carboxyl functional group has been reported in different research works as a possible responsible for the attraction of heavy metals. In the second stage of the thesis, it was studied three operational variables, pH, particle size and biomass/solution ratio and the influence on adsorption was verified. It was worked in three levels of lead concentration, 5, 15 and 30 mg/L and it was found that the highest removal of the metal occurred at pH 5 due to the deprotonation of the carboxyl groups present in the wall cellular bioadsorbent. The results obtained in the adsorption capacities were 7,183, 20,833 and 27,042 mg/g for 5, 15 and 30 mg/L respectively. The granulometry of the biomass was between 177 and 297 microns with a biomass/solution ratio of 0.6 g/L, this values allowed succesful results to remove lead (II) from aqueous solutions. The solid - liquid system reaches the equilibrium after 600 minutes. To know the behavior of the kinetics of the process, two kinetic models were used, describing better the non-linear model pseudo second order results; the correlation factor (R2) were 0.9998 and 0.9997 for 5 and 30 mg/L respectively. The equilibrium in the liquid was described by Langmuir Isotherm. For this study the lead concentration range were between 5 to 100 mg/L, and the maximum capacity was 53,476 mg/g. On the other hand, the equilibrium in the solid was described by the desorption of lead (II) and the best eluent capable of releasing the lead from the cell wall of the bioadsorbent was HNO3 (0.1 N). Finally, the results from this research confirm that the bioadsorbent made from the Brassica nigra is a good alternative to treat polluted water with lead.