Dube S, Matsinha LC, Makhubela BCE, Ambushe AA. Investigating cyanogen rich Manihot esculenta efficacy for Ru phytomining and application in catalytic reactions.
RSC Adv 2022;
12:1165-1176. [PMID:
35425133 PMCID:
PMC8978976 DOI:
10.1039/d1ra06647a]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/18/2021] [Indexed: 11/24/2022] Open
Abstract
Phytomining is a newly developing alternative green technology. This technology has been applied for recovering precious metals from mine tailings that are low-grade ores. In this study, effective catalytic transfer hydrogenation of furfural to furfural alcohol was investigated using a ruthenium (Ru) bio-based catalyst, Ru@CassCat. The catalyst was prepared from Ru rich bio-ore recovered during laboratory scale phytomining as a model of mining tailing using the cassava plant (Manihot esculenta). Pre-rooted cassava cuttings were propagated and watered with Ru rich solutions for ten weeks before harvest. Harvested cassava roots were calcined to produce the bio-ore used as an in situ bio-based catalyst. The properties of the catalyst were characterized by various techniques, which include transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy (SEM-EDS), powder X-ray diffraction (pXRD), ultraviolet-visible (UV-Vis) spectroscopy, thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) theory. Characterization by FTIR, SEM and TEM revealed that RuCassCat has spherical component particles, loosely arranged around a cellulose/lignin-like matrix of the biocatalyst. It was also found that calcination strengthened the structure and texture of the support carbon matrix to distribute the Ru particles evenly. An ICP-MS analysis showed that up to 295 μg g−1 of Ru was detected in cassava roots. The variation of test conditions, namely, temperature, time, base, catalyst load, and a hydrogen source, was investigated. Optimally, a 0.00295 wt% ruthenium loading on the Ru@CassCat catalyst resulted in 100% furfural conversion with a turnover frequency of 0.0114 million per hour at 160 °C for 24 h using triethylamine as a base and formic acid as a hydrogen source. The catalyst remained active for up to three recycles, consecutively and produced furfural alcohol in high turnover numbers.
Effective catalytic transfer hydrogenation of furfural into furfural alcohol was accomplished using a bio-based Ru catalyst, Ru@CassCat. The catalyst was successfully produced from cassava biomass grown in Ru-rich laboratory soils.![]()
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