Pyrolytic temperature evaluation of macauba biochar for uranium adsorption from aqueous solutions

Abstract

This study aims to evaluate the effect of the pyrolytic temperature on the biochar derived from the macauba endocarp for the removal of uranium (VI) from aqueous solutions. The endocarp was subjected to six different pyrolytic temperatures, ranging from 250 ºC to 750 ºC. The biochars obtained at each temperature were evaluated for their adsorption capacities ("q"). The highest adsorption capacities were obtained for the biochar produced at 250 ºC (BC250), followed by the one obtained at 350 ºC (BC350), with removal efficiencies of 86 % and 80 %, respectively. The best condition was achieved when the endocarp was subjected to temperatures between 300 and 350 °C, at which it was possible to obtain a satisfactory balance among adsorption capacity, gravimetric yield and fixed carbon content. This characteristic, combined with the high removal efficiency, points to an ideal working temperature of 350 °C. Elemental analysis showed a decrease of the H/C and O/C ratios when higher pyrolytic temperatures were applied, indicating an inverse relationship between the carbonization and the surface polar functional groups, which were likely responsible for an increased adsorptive capacity in biochars produced at lower temperatures. Both FTIR and XPS analysis indicated that oxygen-containing groups such as hydroxyls and carboxylic acids were involved with the binding of uranyl ions.

Induced changes of pyrolysis temperature on the physicochemical traits of sewage sludge and on the potential ecological risks

“…3 ) indicated that the SS material has more H relative to FC, while the biochar produced at high pyrolysis temperatures has less H relative to FC. Working with biochar derived from macaúba endocarp pyrolyzed at temperatures from 200 to 700 °C 56 , reported a similar relationship between H/C and FC. The reduction in the H/C ratio at higher temperatures also results from the breakup of oxygen-containing functional groups, such as carboxyl, carbonyl, and methoxyl, and the formation of aromatic compounds 57 .…”

Influence of pyrolytic temperature on uranium adsorption capability by biochar derived from macauba coconut residue

“…BC350 was selected for the preliminary experiments based on a previous study [26], in which the gravimetric yield factor was used to identify the temperature at which to obtain a biochar with the maximum fixed carbon content and gravimetric yield. In this case, the gravimetric yield obtained for BC350 was of 46.09 % and the fixed carbon content was of 60.22 %, rendering a gravimetric yield factor of 0.28 %, which, by comparison, qualified 350 °C as the operational HTT.…”

EPs Antibiotics: Photodecomposition and Biocarbon Adsorption

“…The MB is excited under the red region of the light source and received electrons to the excited MB which produces an anion which abstracts a proton from water to provide LMB; the LMB is very readily re-oxidized back to MB if there is any oxygen in the solution [9,10,21].…”