Reduction of Bromate by Cobalt-Impregnated Biochar Fabricated via Pyrolysis of Lignin Using CO₂ as a Reaction Medium

Abstract

In this study, pyrolysis of lignin impregnated with cobalt (Co) was conducted to fabricate a Co-biochar (i.e., Co/lignin biochar) for use as a catalyst for bromate (BrO) reduction. Carbon dioxide (CO) was employed as a reaction medium in the pyrolysis to induce desired effects associated with CO; (1) the enhanced thermal cracking of volatile organic compounds (VOCs) evolved from the thermal degradation of biomass, and (2) the direct reaction between CO and VOCs, which resulted in the enhanced generation of syngas (i.e., H and CO). This study placed main emphases on three parts: (1) the role of impregnated Co in pyrolysis of lignin in the presence of CO, (2) the characterization of Co/lignin biochar, and (3) evaluation of catalytic capability of Co-lignin biochar in BrO reduction. The findings from the pyrolysis experiments strongly evidenced that the desired CO effects were strengthened due to catalytic effect of impregnated Co in lignin. For example, the enhanced generation of syngas from pyrolysis of Coimpregnated lignin in CO was more significant than the case without Co impregnation. Moreover, pyrolysis of Coimpregnated lignin in CO led to production of biochar of which surface area (599 m g) is nearly 100 times greater than the biochar produced in N (6.6 m g). Co/lignin biochar produced in CO also showed a great performance in catalyzing BrO reduction as compared to the biochar produced in N.

Bromate Oxidation of Ammonium Salts: In Situ Acid Formation for Reservoir Stimulation

“…Specific ion effects have been observed to play a role not only in macromolecular biological systems such as proteins, but also in polymers and colloids, and may find an important place among environmental processes . Further, the chemistry of bromine continues to be an active area of investigation, across the various oxidation states including Br – , Br 2 , BrO – , − BrO 2 – , − and BrO 3 – . ,, Their presence in natural environments and utility in chemical transformations continue to drive the various avenues of interest.…”

“…57 Further, the chemistry of bromine continues to be an active area of investigation, across the various oxidation states including Br − , 58 Br 2 , 59 BrO − , 60−63 BrO 2 − , 63−65 and BrO 3 − . 51,66,67 Their presence in natural environments and utility in chemical transformations continue to drive the various avenues of interest.…”

Towards practical application of gasification: a critical review from syngas and biochar perspectives

“…The reduction process using steam or CO2 as the gasifying agent was similar to the physical activation processes that were used to produce activated carbons (Lee et al, 2017c;Manyà, 2012;Xiu et al, 2017). Hence, the reduction stage using steam or CO2 serves as an activation step to increase the specific surface area and micropore volume of the biochar, despite that the improvement in the surface properties corresponds to a loss in carbon sequestration capacity (Cho et al, 2017a;Manyà, 2012).…”

Plasma-deposition of α-FeOOH particles on biochar using a gliding arc discharge in humid air: a green and sustainable route for producing oxidation catalysts

“…[15][16][17][18] In addition, biochars have been used as bio-based supports for heterogeneous catalysts preparation. [19][20][21] While using biochar as a catalyst support, a substantial dual functionality in biocharmetal oxide composites such as TiO 2 -biochar 22 and Co 2 O 3biochar 23 has been proven in oxidative degradation of organic pollutants. Accordingly, the future prospects of using biochar in heterogeneous catalysis appear very bright.…”