Reduced adsorption of propanil to black carbon: Effect of dissolved organic matter loading mode and molecule size

Abstract

In the present study, the reduced adsorption of propanil on black carbon (BC) influenced by dissolved organic matter (DOM) was verified to be closely related to DOM molecule size and loading mode. Two congenetic carbons, a rice-residue-derived BC and the reduced product (RC), were characterized by similar specific surface area and different surface properties. Reduced product exhibits higher adsorption of propanil and DOM than BC. A series of model DOMs, including tannic acid (TA), pentagalloylglucose (PA), 3-O-galloylmucic acid (OA), and gallic acid (GA), characterized by different molecule sizes and molecular weights, were used to evaluate the different inhibitory effects. The DOM adsorption (mmol/g) on BC and RC follows the order of GA > PA > OA > TA, whereas the reduction of propanil adsorption influenced by the model DOM follows the order of PA ≈ TA > OA ≈ GA. The suppressive degree is connected to their molecule sizes rather than to molecular weights. Tannic acid and PA weakened propanil adsorption more effectively than OA and GA because the large DOM molecules may hinder propanil molecules into the micropore regions. Because of the similar molecule size, TA and PA present a similar suppressive effect on propanil adsorption. The influence of the DOMs was greater when preloaded than when in competition with propanil. The preloading of macromolecules (TA and PA) and OA on the carbons may lead to secondary and primary micropore blocks, respectively. The preloading of GA may cause partial GA molecule sequestration in the primary micropore, thus leading to strong attenuation of propanil adsorption on the carbons.

Relationships between aging of PAHs and soil properties

“…Moreover, the strong sorption domain (i.e. the micropore system) of the tiny BC fraction in the soils might be blocked or occupied by soil components such as DOC and mineral clays, thus attenuating the possible influence from BC (Kwon and Pignatello, 2005;Brändli et al, 2008;Xiao et al, 2012). Agarwal and Bucheli (2011) also observed the only governor of TOC in the distribution of PAHs in the organic carbon-rich agricultural soils.…”

Effects of Solvent Molecules on the Interlayer Spacing of Graphene Oxide

“…This relationship has been demonstrated in other carbon materials [24]. Our simulation results showed that the maximum numbers of water, EG, DMF, and NMP molecules that can be adsorbed per unit cell of GO are 490, 120, 97, and 70, respectively.…”

“…The hydrodynamic diameter of a water molecule is ~ 2.7 Å [25]. The intercalation of a water monolayer causes the lattice of GO to expand by 2.2-2.5 Å [24]. The size of the DMF layer adsorbed by GO structure is ~ 4.4 Å [26].…”

Mechanisms and Factors Influencing Adsorption of Microcystin-LR on Biochars

“…After coexisting with 5 mg L −1 TA and GA, the maximum adsorbed capacity (q m ) of MCLR decreased to 92 and 6 %, respectively (Table 6S). This result indicated that TA acted as a strong competitor by occupying the effective adsorption sites for MCLR in the mesopore and macropore regions because of the larger molecule size of TA (1.93 nm×1.73 nm×1.32 nm) than MCLR (Xiao et al 2012). However, GA shows a slight influence on MCLR adsorption because the dominant adsorptive domain for GA is micropore, which is inaccessible to MCLR macromolecules.…”

“…The three-dimensional size of MCLR was reported as 1.9 nm×1.5 nm×1.1 nm (Teng et al 2013). Therefore, the micropore regions (pore size <2 nm) may be unavailable for MCLR adsorption because the second widest dimension of MCLR (1.7× 1.5=2.55 nm) is 1.7 times larger than 2 nm (Xiao et al 2012). This notion is supported by evidence that the uptake of MCLR on micropore-based carbon is similar to that on nonporous carbon (Pendleton et al 2001).…”