Surface properties of bentonite and illite complexes with humus acids

Abstract

In this study, the reaction between humus acids (humic acid and β-humus fulvic acid fraction) and bentonite and illite was studied at a variety of pH values. The degree of reaction was determined from the specific surface area and molar energy of adsorption. Characteristic parameters of adsorption isotherms for the formation of a mono-layer of the adsorbent, such as the constant C from the BET equation, mono-layer capacity (Nm), and standard error square (R2), were also included in the study. After the addition of humus acids, the specific surface area of illite and bentonite decreased at all pH values, reaching a minimum at pH 4. This indicates different degrees of reaction of humus acids with the clays and, probably, partial hydrophobization of the materials. The degree of reaction of humus acids with the minerals depended on the pH and, for certain combinations, it was highest at pH 4. This value is relatively close to that at which the humus acid fractions in question precipitate from solution.

Integrated investigations on the adsorption mechanisms of fulvic and humic acids on three clay minerals

“…Compared to FA, HA molecules are larger in size (higher molar mass), contain more carbon, and are less soluble [8]. Although a number of studies have been performed on the adsorption of FA/HA on clays [6,[12][13][14], how the differences in characteristics of FA and HA such as composition and particle size result in their different adsorption behaviors on clays has not been well elucidated. Furthermore, adsorption of FA/HA on minerals was dependent on the surface properties of the minerals [16].…”

“…The 1 H NMR results (Fig. 3) indicated that aliphatic moieties (0.8-2.2 ppm regions), aromatic moieties (6.5-8 ppm regions) [14,24] and a combination of amino acids, polysaccharides, aromatic methoxyl, or other moieties such as esters and ethers (3-5.5 ppm regions) [14,25] were the dominant fractions in the equilibrium solutions, while the strong signals at 2.50 ppm and 3.35 ppm were attributed to DMSO-d 6 and H 2 O [25,26], respectively. Fe was detected at 1.72 and 2.13 mg/L in the equilibrium solutions after FA and HA reacted with vermiculite, and the slightly broader peaks for unbound FA/HA after adsorption on vermiculite (Fig.…”

“…Interactions between NOM and clay minerals are expected to modify surface properties and reactivity of clay minerals [6,7], and change the mobility of pollutants bound to them [8,9]. Therefore, investigation of the interactions between NOM and clay minerals is the basis not only for understanding the interfacial properties of soils and sediments, but also for elucidating behaviors of contaminants in the natural environments [10,11].…”

Role of Caustic Addition in Bitumen–Clay Interactions

“…Taking an average of 6 measurements, the WDPT for illite particles treated in Milli-Q ® water with 40 ppm Ca 2+ as the base line was measured to be 26±4. wt.% NaOH tailings water containing 50 ppm humic acids does not greatly modify either the wettability or the surface charge of the particles, it does induce steric repulsion between humic acids adsorbed on both bitumen and illite [65][66][67] , reducing the deposition activity of illite clay particles which is highly desirable. Further work in this area is needed to further explore the nature of interaction.…”

Sorption and Desorption of Atrazine on Natural Bentonite and Organically Modified Bentonite

“…In Humic bentonite complex, low surface area probably attributed to coating the outer surface of bentonite particles with humic acid. Ksiezopolska and Pazur (2011) reported that the specific surface area of bentonite and illite reduced after complexion with humic acids at all pH values as a result of lodged humic acid in the active sites on clays and making the surface of the complex hydrophobic. Whereas, in surfactant modified bentonite the interparticle pores are covered and clogging of the interlayer space by HDTMA molecules prevented the N 2 access to the inner surface of material Erdem et al, 2010;Emam 2013).…”