Impact of coal structural heterogeneity on the nonideal sorption of organic contaminants

Abstract

Carbonaceous geosorbents (black carbon, coal, and humin/kerogen) play a primary role in the nonideal sorption (isotherm nonlinearity, hysteresis, and multiphasic kinetics) of hydrophobic organic chemicals by soils and sediments. The present study investigated the impact of coal structural heterogeneity on sorption/desorption of two model monoaromatic compounds (1,3-dichlorobenzene and 1,3-dinitrobenzene). Due to the higher degree of aromaticity and condensation, anthracite showed stronger sorption affinity and nonlinearity and slower sorption kinetics than lignite. Removal of humic substances by alkali extraction and/or mineral fraction by acidification did not much affect organic carbon-normalized sorption coefficient to the coal, suggesting nearly complete accessibility of adsorption sites on the condensed organic carbon. However, the treatments greatly increased sorption kinetics and meanwhile alleviated hysteresis of 1,3-dinitrobenzene, as compared with the original lignite. These observations were attributed to the enhanced exposure of high-energy adsorption sites on the condensed organic carbon after exfoliating the surface coverage by humic substances and minerals. An empirical biphasic pseudo-second-order model consisting of a fast sorption phase and a slow sorption phase adequately quantified the overall sorption kinetics for the coal sorbents. The results indicated that the condensed organic carbon, in combination with other structural components, controls the nonideal sorption of unburned coal.

Micropore clogging by leachable pyrogenic organic carbon: A new perspective on sorption irreversibility and kinetics of hydrophobic organic contaminants to black carbon

“…The sorption kinetic data were described by an empirical biphasic pseudo-second order model consisting of a fast sorption phase and a slow sorption phase (Shi et al, 2011;Yang et al, 2008), expressed as:…”

Investigation of MCHM transport mechanisms and fate: Implications for coal beneficiation

“…Morris (2013) indirectly measured the partitioning behavior of frothers methyl isobutyl carbinol (MIBC) used in the Appalachian coal industry and the results indicate a significant frother sorption to coal surfaces. A few studies on organic contaminants (PAHs, phenanthrene and methanol) indicate strong nonlinear sorption of these chemicals to coal and soot (Shimizu et al, 1998;Jonker and Koelmans, 2002;Cornelissen et al, 2006;Shi et al, 2011).…”

The Characteristics of Limestone and Anthracite Coal as Filter Media in Treating Pollutants from Groundwater

“…2, the anthracite coal originates from quartz (ICDD No: 01-089-8935) and graphite (ICDD No: 01-075-2078) crystalline phases. Quartz appearing at 37.20° is assigned as calcium silicate [12]. The main element present in anthracite is carbon.…”

“…Anthracite coal was imported from the United Kingdom, placed on the top layer of sand filter and traps large particles when the water comes in contact with the media during filtration. Shi et al, (2011) reported that anthracite contains the highest carbon content (90% to 100%) compared with lignite (60% to 75%) and hard bituminous coal (80% to 90%) [12]. Apart from having the highest carbon content, it has extremely low impurities.…”