Comparison of XAD macroporous resins for the concentration of fulvic acid from aqueous solution

Abstract

Five macroreticular, nonionic Amberlite XAD resins were evaluated for concentration and isolation of fulvic acid from aqueous solution. The capacity of each resin for fulvic acid was measured by both batch and column techniques. Elution efficiencies were determined by desorption with 0.1 N NaOH. Highest recoveries were obtained with the acrylic ester resins which proved to be most efficient for both adsorption and elution of fulvic acid. Compared to the acrylic ester resins, usefulness of the styrene divinylbenrene resins to remove fulvic acid Is limited because of slow diffusion-controlled adsorption and formation of charge-transfer complexes, which hinders elution.There is a growing interest on the part of researchers to determine the contribution by humic substances to biological, physical, and geochemical processes in natural water systems. These substances, which constitute a ubiquitous class of naturally occurring, polyelectrolytic organic compounds, are known to play a role in the food chain, to affect the aesthetic quality of water by imparting color, to act as complexing agents for inorganic ions, and to aid in the movement of less soluble organic compounds, such as pesticides, in the aqueous environment (1). In addition, it is known that humic substances are precursors for haloforms in waters treated by chlorination ( 2 ) . The further study of these substances requires that they be efficiently isolated and concentrated from natural water.In recent years, it has been found that high recoveries of organic compounds from water are possible with macroreticular Amberlite XAD resins (3). These resins are nonionic, macroporous copolymers which possess large surface areas. There has been much study of the use of XAD resins for isolation, concentration, and chromatographic separation of many chemically distinct classes of compounds ( 4 , s ) . Some work has also been done with more chemically complicated humic substances. XAD-1 and XAD-2 have been shown to be effective adsorbents for removal of humic substances from seawater (6, 7), and XAD-2 has been used to isolate these substances from river water (8). Use of these resins for concentration and isolation of humic substances from natural waters is an improvement over activated carbon, because they are easier to elute and are free from the risk of chemical alteration of the humics (6). In addition, XAD resins have greater adsorption capacities and are easier to elute than alumina, silica gel, nylon, and polyamide powder (6).This paper presents a comparison and evaluation of five XAD resins for isolation and concentration of fulvic acid from water. A second objective of this research is to obtain a better understanding of the adsorption process of these poorly defined, albeit omnipresent, environmental compounds. E X P E R I M E N T A L Resin. The five resins studied (Table I) differ in pore size, surface area, polymer composition, and polarity (9). Three of the resins XAD-1, XAD-2, and XAD-4, are styrene divinylbenzene copolymers, which are not easily wetted an...

Binding of cationic surfactants to humic substances

“…Dando humic acid (DHA) and Inogashira humic acid (IHA) are supplied by the Japanese Humic Substance Society (JHSS) and they are isolated according to the method recommended by the International Humic Substance Society (IHSS) [40]. DHA was extracted from brown forest soil in Dando, Aichi Prefecture, and has an ash content of 0.67%.…”

“…Strichen Bs fulvic acid (SFA) is extracted from a Bs horizon from a peaty podzol (Strichen Soil Association, Scotland) using the methods recommended by the IHSS [40].…”

Humic substance charge determination by titration with a flexible cationic polyelectrolyte

“…Dando humic acid (DHA) and Inogashira humic acid (IHA) are standard HA samples supplied by the Japanese Humic Substance Society (JHSS) and they were isolated according to the method recommended by the International Humic Substance Society (IHSS) (Aiken et al, 1979). DHA was extracted from Black Forest soil and IHA was extracted from Ando soil.…”

“…Strichen fulvic acid (SFA) was extracted from a Bs horizon of a peaty podzol (Strichen Soil Association, Scotland) using the methods recommended by the IHSS (Aiken et al, 1979). Literature data regarding the elemental composition and average particle masses of the samples are summarized in Table 1.…”

The comparison of fulvic acids extracted from the primary and secondary effluent

“…FA were extracted from the collected material in a laboratory. FA were isolated from the collected samples in accordance with the procedure [16,17]. The concentration of the FA solution was determined in a vacuum evaporator and was specified by the determination of dry residue.…”