Constituents And Structure Of Different Types Of Natural Organic Matter And Their Effects On The Sorption Of Phenanthrene And Nonylphenol

Sorption of hydrophobic organic compounds(HOCs) in natural organic matter(NOM) is an important process because it governs the distribution, transport and fate of these compounds in natural environment. NOM exhibits high heterogeneity, and contains a variety of different types of organic matter, including young biopolymers, middle aged humic substances, old aged geosorbents such as kerogen, and incomplete combustion products of organic materials such as black carbon. The sorption mechanisms of HOCs by these types of NOM are different. As the structure and composition of organic matter is a major factor that affecting the sorption behaviors of HOCs, it is very important to acquire accurate quantitative information of the structure and composition of NOM. Moreover, as one of the bioremediation stratigies, biosorption can be used in the removal of HOCs in the aquaticenvironment. Therefore, the further understanding the sorption mechanisms between HOCs and NOM is important for the control and remediation of HOCs in the aquaticenvironment.The biosorption of HOCs on pure algae, field-collected planktons and their algal fractions were investigated. Three commercial algal species, two cultured algal species and three field-collected plankton samples were collected and selectively fractionated into different organic fractions. The advanced NMR techniques were used to quantitate the concentrations of different functional groups. These algal organic fractions were characterized and used as biosorbents for phenanthrene(Phen) and nonylphenol(NP).The biosorption behaviors of Phen and NP were compared, and were related to the compositions and properties of the algal samples to infer the possible biosorption mechanism. The Phen sorption for the nonhydrolyzable organic carbon(NHC) in pure algae and field-collected planktons was nonlinear, that for alkaline nonhydrolyzable organic carbon(ANHC) was slightly nonlinear, and that for the other fractions was linear. The LP and NHC fractions exhibited higher sorption capacities for Phen and NP than other fractions did. The sorption capacities for the original pure algae and field-collected plankton samples were related to their lipid(LP) contents. The sorption capacities for the pure algae, field-collected planktons and their fractions were negatively related to their polar groups such as alkyl C-O and polar C, and positively to alkyl carbon and poly(methylene) carbon, indicating the importance of polarity and aliphatic structure. The higher sorption capacities observed for NP than for Phen on the investigated algal samples are explained by specific interactions such as hydrogen bonding and π-π interaction.Two pollen and two moss samples were collected and separated into different organic fractions. These samples and their fractions were characterized and used as biosorbents for Phen to investigate the important effect of the structure and composition of bimasses on the biosorption of Phen. The structure of the NHC fractions in pollen samples issimilar to that of sporopollenin, exhibiting high aliphatic nature, whereas the NHC fractions of moss sampes exhibited relatively higher aromatic nature. Pollen organic fractions exhibited greater sorption capacity and higher nonlinearitythan moss organic fractions did, indicating the importance of the type of organic matter. The sorption capacities of the pollen and their fractions were negatively related to polar groups, and positively to alkyl carbon, poly(methylene) carbon and aromatic carbon, respectively, indicating the combined contributionof polarity, and aliphatic cabon as well as aromatic carbon structure.Three surface sediment samples were collected and selectively fractionated into different organic fractions. These samples and their fractions were used as sorbents for Phen and NP to examine the sorption behaviors and mechanisms of Phen and NP. The DP/MAS 13 C NMR spectra indicated that the NHC fractions inthe sediments contained high contents of aromatic carbon, which ranges from 64.07% to 73.10%. After being solvent extracted, the lipid free(LF) fractions exhibited greater sorption capacity than the demineralized(DM) fractions did, indicatding that the presence of LPcouldblock the accessibility of sorption sites for Phen and NP. The sorption capacities of the sediment and their fractions were negatively related to alkyl carbon and protonated aromatic carbon, and positively to nonprotonated aromatic carbon, respectively. The sorption nonlinearity(n) of the sediment and their fractions were negatively related to nonprotonated aromatic carbon, but positively to protonated aromatic carbon. These correlations demonstrate that nonprotonated aromatic carbon is the main factor leading to the increasingsorption capacity and nonlinearity. The higher sorption capacities observed for NP than for Phen on the investigated sediment samples are explained by specific interactions such as π-π interaction.The structure and composition of sequentially alkalinely-extracted kerogen, and the sorption behaviors of Phen on the different kerogen fractions were investigated. A type II kerogen was extracted from a Maoming shale, and treated by different chemical procedures. The isolated four shale fractions include the following: bulk kerogen(BK),organic solvent extracted kerogen(SEK),alkalinely-extracted kerogen fractions(EKs) at 20 °C, 40 °C and 60 °C, respectively, and residual kerogen(RK). After these kerogen fractions were characterized by using elemental and stable carbon isotopic composition analyses, X-ray photoelectron spectra, a suite of advanced solid-state NMR techniques, and surface area and porosimetry analysis, the sorption isotherms of Phen on these kerogen fractions were established in order to examine the differences in chemical and structural properties among different kerogen fractions and to investigate their sorption behaviors of Phen. It was found that the yields of total extracted EKs at 20 °C, 40 °C and 60 °C were 10.47%, 20.60% and 27.9%, respectively, indicating that considerable amounts of kerogen were dissolved, and temperature was an important factor influencing the yields of EKs extracted from BK fraction. Aromatic moieties(C-C, C-H and C-O) were the dominant organic structure in EKs, representing more than 60% of total carbon in these samples. The composition and structure of EKs were obvious different from those of BK, RK60 and SEK fractions, in which nonpolar aliphatic carbon were the dominant constituents. The aromatic moieties of EKs were more soluble in base solutions and were relatively easily extracted from BK, whereas the aliphatic moieties of EKs were less soluble in base solutions and were relatively hardly extracted from BK. After being alkalinely-extracted, RK60 contained lower aromatic carbon content than BK did.After being solvent-extracted, SEK had lower nonpolar aliphatic carbon content than BK did. New evidence is given to an alternative understanding of the supramolecular view of kerogen, which is assumed to be stabilized predominantly by weak dispersive forces such van der Waals, π-π, δ-π and hydrogen bonds. This investigation supplies a new phenomenon that kerogen could bedissolved gradually indilute alkaline solutions.The CO2 adsorption data indicated that specific surface areas and the micropore volumes of EKs were higher than those of bulk BK and RK60. The latterly extracted EKs exhibited greater sorption affinity and more nonlinear sorption behavior than the earlier extracted EKs, indicating that the relatively polar and weak sorption affinity domains in EKs were easily extracted. The sorption behaviors of EKs were different from those of BK, RK60 and SEK. After being alkalinely-extracted, RK60 showed decreasing sorption capacity, but after being solvent-extracted, SEK showed increasing sorption capacity. For EKs, the Phen sorption capacity was positively correlated with H/C atomic ratios and nonpolar aliphatic carbon, butwas inversely related to O/C atomic ratios and aromatic carbon. The nonlinear factor(n) was positively correlated with nonprotonated aromatic carbon, but wasinversely related nonpolar aliphatic carbon. These correlations indicated that the kerogen samples containing low nonprotonated aromatic carbon and more nonpolar aliphatic carbon exhibited greater sorption affinity and more nonlinear sorption. The Phen sorption capacity in EKs was also related to specific surface areas and the micropore volumes, indicating the potential importance of microporosity.