Download This PaperNew Composite of Pecan Nutshells Biochar-Zno For Sequential Removal of Acid Red 97 by Adsorption and Photocatalysis
30 Pages Posted: 22 Apr 2020
Abstract
A new composite, biochar derived from pecan nutshell with ZnO (biochar-ZnO) was prepared, characterized, and applied as an alternative and low-cost biosorbent-photocatalyst for degrading Reactive Red 97 (RR97) from aqueous solutions. Composites with different ratio of ZnO supported in the biochar were produced using mechanical mixing and pyrolysis in a reducing atmosphere from N2 at 650 ºC. The interest in supporting ZnO in biochar is to produce a material with superior sorption and photocatalysis capacity in relation to the precursors separately. The composite produced has intrinsic characteristics, besides favoring its removal from the solution and enabling its use in reuse cycles, reducing the band gap energy, and increasing the surface area of the photocatalyst. It was possible to relate the band gap energy of the composites with the photocatalytic capacity and the functional groups with the sorption capacity, varying the pH of the solution and the ZnO content. It was observed that the degradation efficiency is related to the greater amount of ZnO supported in the biochar (N20Z), lower band gap energy and greater surface area, where in natural pH (pH 7) 100% of degradation was reached in 67 min (30 min biosorption + 37 min photocatalysis). The ease of removing the composite from the solution allowed nine recycles to be carried out, and the physical-chemical stability of the same ensured an efficiency of 100 to 90% at the end of the ninth cycle.
Keywords: composite, biochar, ZnO, photocatalysis, RR97 dye
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