Application of the Biomass from the Shell of Pachyrhizus erosus in the Removal of Hexavalent Chromium from Contaminated Waters

Abstract

Aims: Recently, the removal capacity of different heavy metals from sites contaminated by low-cost materials has been studied, with promising results. These adsorbents include dead microorganisms, clay minerals, agricultural waste, industrial waste, and other materials. The objective of this work was studying the removal capacity of Chromium   (VI)  by   the  biomass of the shell of Pachyrhizus erosus, by  the Diphenylcarbazide colorimetric method. Place and Duration of Study: Sample: Faculty of Chemical Sciences. Autonomous University of San Luís Potosí, S.L.P., between July and November 2021. Methodology: The biomass was obtained from the shell of P. erosus, acquired in the Republic market of the city of San Luís Potosí, during the month of July 2021.  For  obtain the biomass, the shell was washed during 24 hours in EDTA at 10% (p/v), and 1 week with tridesionized water under constant stirring, with water changes every 12 hours, and we work with 100 mL of a 100 mg/L solution of   Chromium  (VI) obtained by diluting a 1 g/L standard solution prepared in tridesionized water from K2Cr2O7. The pH of the solution was adjusted with 1 M H2SO4 and/or 1 M NaOH, before adding it to the biomass. Results: The highest bioadsorption was at 7 hours, at pH 1.0 and 28°C. Regarding temperature, the highest removal was at 60°C and 1.5 hours, with a removal of 90.69%. At the metal concentrations analyzed, the natural biomass showed a good removal capacity, in addition too efficiently removal the metal in situ (93.6% of contaminated water), at 3 days of incubation, with 5 g of biomass, and 100%  of  removal from contaminated earth, at 52 hours of incubation, with 5 g of biomass). Conclusion: Therefore, this biomass can be used to remove it from industrial wastewater and contaminated earth.