Comparison of adsorption capacity of young brown coals and humic acids prepared from different coal mines in Anatolia

Removal of hexavalent chromium from aqueous solutions by D301, D314 and D354 anion-exchange resins

“…Hence, it is necessary to remove chromium from rinse water. Removal of chromium has been investigated by using phytoextraction, reverse osmosis, adsorption, precipitation, ion-exchange, membrane and biological processes [6][7][8][9][10]. The traditional techniques are based on chemical precipitation coupled to pre-or post-oxidation/reduction followed by filtration in order to concentrate the species of interest.…”

Sorption of metal ions on lignite and the derived humic substances

“…The special merit of lignite and weathered coal (leonardite and oxihumolite) is a high content of exchangeable functional groups that makes them an effective medium for the removal of metals from wastewater, e.g., Refs. [2][3][4][5][6][7][8]. The major reservoir of the functional groups in these low-rank coals are humic substances (HS): humic and fulvic acids extractable with strong alkali, and humin-a solid residue remaining after the alkali extraction, which is strongly associated with the coal mineral matrix.…”

Humic and Fulvic Acids as Potentially Toxic Metal Reducing Agents in Water

“…These groups are the active center of the ion‐exchange. So, the lignite‐based materials can be used as an alternative cation‐exchanger, and the fact that they are plentiful and inexpensive makes them an attractive option for the removal of metals from water. Therefore, lignite represents a potential low‐cost sorbent of toxic metals for use in water treatment, groundwater remediation, and construction of active geochemical barriers …”

“…[3] The long-term intake of drinking water containing even low concentrations of heavy metals may cause fatal diseases by the accumulation of heavy metals in the internal organs of human body. [4] Therefore, it is necessary to appropriately remove them through various water treatment processes for satisfying the water quality standard, such as complexing agents ethylene diamine tetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), [5] potassium ferrate, [3] total organic carbon, [6] carbonate hydroxylapatite, [7] nanoporous gold, [8][9][10] humic and fulvic acids, [1,[11][12][13][14] and humic/fulvic acids by miscellaneous nanomaterials. [15] Humic and fulvic acids make up an important part of soil organic matter, and their binding capacity affects the fate of metal ions and plays an important role in their mobility.…”

“…[19] Lignite, the youngest type of coal located between the peat and brown coal on the caustobiolites scale, [20] contains large amounts of humic and fulvic acids, with the former predominating. [11] It is assumed that humic substances are the main components responsible for sorption of metals on lignite (particularly, their carboxylic and hydroxyl-phenolic groups). These groups are the active center of the ion-exchange.…”