Hydrogen peroxide oxidation of humic acids and lignite

Preparation of high-dispersion Ni/C catalyst using modified lignite as carbon precursor for catalytic reforming of biomass volatiles

“…The oxidation of lignite may play an important role in improving of SSA and microporosity and the amount of ion exchange in catalyst preparation. Potassium permanganate, peroxyacetic acid, sodium hypochlorite, oxygen and hydrogen peroxide were used for increasing OCSs content [14][15][16][17][18][19][20], especially for environmentally friendly oxidant of hydrogen peroxide [21,22]. The ion exchange capacity of the lignite can be enhanced by oxidation treatment to provide the carboxyl group.…”

Study of water-extractable fractions from South Moravian lignite

“…The occurrence of such acids was previously reported by other authors utilizing various methods as alkaline hydrolysis, oxidation processes or thermochemolysis of humic substances (Doskočil et al 2014;Hänninen and Niemelä 1992;Estournel-Pelardy et al 2013). They are considered as cross-linkages between aromatic structures of humic substances (Doskočil et al 2014). It is known that methyl succinic acid can arise from cleavage of an aromatic ring (Joll et al 2003).…”

“…Lignite is mainly used for energy production but its disadvantages are low caloric value and high water content. In this regard, non-energy or non-fuel applications can represent more interesting use of this valuable raw material [e.g., a production of small acids by chemical treatments (Doskočil et al 2014)]. …”

The Role of Carboxyl and Hydroxyl Groups of Humic Acid in Removing AuCl₄^- from Aqueous Solution

“…Therefore, it is reasonable to assume that the -OH groups of HAs also play an important role in the removal of AuCl4 -from the solution through reduction to Au metal. Thermodynamically, AuCl4 -with a reduction potential of 1.002 V should be readily reduced by HSs, since the reduction potentials of HSs range from 0.5 V to 0.7 V [45][46][47].…”