Importance of Sporopollenin Structure and Accessibility in the Sorption of Phenanthrene by Biota Spores and Pollens

Structural characteristics of dissolved black carbon and its interactions with organic and inorganic contaminants: A critical review

Biochar (BC) is a sustainable and renewable carbonaceous material, and its soluble component, dissolved black carbon (DBC), is the key to understanding BC's geological and environmental processes. Although the relationship between the changes in DBC structure and its properties, functions, and associated environmental risks has been explored, a gap remains in our understanding of DBC's fate and behavior in the natural environment. Thus, in this review, we have highlighted the molecular and chemical compositions and the structural evolution of DBC during pyrolysis, the influence of DBC's physicochemical properties on its fate and transport, DBC's interaction with soil and its contaminants, and DBC stability in soil and water environments along with potential risks. Based on our in-depth assessment of DBC and its biogeochemical roles, we believe that future studies should focus on the following: (1) using advanced techniques to understand the chemical and molecular structure of DBC deeply and concisely and, thus, determine its fundamental role in the natural environment; (2) investigating the multi-functional properties of DBC and its interaction mechanisms; and (3) evaluating the environmental behaviors of and risks associated with DBC after BC application. In future, it is necessary to gain a deeper insight into the fate and transport of DBC with contaminants and study its associated risks under BC application in the environment.

A novel biosorbent functionalized pillar[5]arene: Synthesis, characterization and effective biosorption of Cr(VI)

Among toxic chemicals, hexavalent chromium (Cr(VI)) is one of the most carcinogenic and toxic pollutants that hostiles to the health of both humans and other living things. Therefore, the removal of Cr(VI) is of great importance to keep our environment clean and tidy. In this study, an easy-make, inexpensive, and natural biosorbent material (Sp-P[5]) was prepared to preserve our environment using a pillar[5]arene based-on sporopollenin microcapsule. The prepared biosorbent was successfully characterized by some techniques such as FTIR, XRD, and SEM. The biosorbent, Sp-P[5], exhibited an open mesoporous structure richly decorated with multi-amine-containing moieties resulting in enhanced Cr(VI) sorption. The sorption behavior of Cr(VI) ions is satisfactorily adapted from the sorption kinetics pseudo-second-order law and the isotherm models to the Langmuir model at different temperatures. The Langmuir model fits at different temperatures (298-328 K) and the maximum sorption capacities of the Cr(VI) ion ranged from 106.38 to 117.26 mg/g. The thermodynamic calculations reveal that the sorption of Cr(VI) ions on the Sp-P[5] is entropy-driven, endothermic, and spontaneous. The prepared biosorbent was also applied to the natural wastewater samples and different ions (chromate and dichromate). The sorption and desorption experiments showed that the sorption efficiency for Cr(VI) ions of the Sp-P[5] decreased to 70.88 % after 8 cycles. As result, the synthesized biosorbent, Sp-P[5], has outstanding potential in the removal of Cr(VI) ions from water bodies and natural wastewater systems.

The chemical structure characteristics of dissolved black carbon and their binding with phenanthrene

The elucidation of interactions between the dissolved black carbon (DBC) in biochar and hydrophobic organic contaminants (HOCs) is crucial for controlling the environmental behavior of HOCs. The complicated chemical structures of DBCs result in diverse interaction mechanisms between DBCs and HOCs, which were driven by different chemical structures in DBCs. In the present study, ten DBCs were extracted from rice straw and corncob biochars and their chemical structures were characterized and analyzed. The binding of phenanthrene (Phen) with DBC were studied through fluorescence quenching experiments. DBCs with low concentration (1 mg C/L) were found to complex with high amounts of Phen per unit mass. No significant difference was found in the amount of the bound Phen per unit amount of DBC when the concentration of DBC increased beyond >5 mg C/L. The dominant mechanisms involved in the binding of Phen by DBCs are speculated to be hydrophobic interactions, π-π electron donor-acceptor (EDA), and chemical partition, which was driven by the fatty carbon chain, aromatic rings, and quinone groups or ester groups, respectively. This study elucidates the interactions between DBC and Phen, which is of great significance for understanding the environmental behavior of HOCs.

Dynamics in imidacloprid sorption related to changes of soil organic matter content and quality along a 20-year cultivation chronosequence of citrus orchards

The on-going and extensive use of neonicotinoids occur in orchards. However, it is still unknown whether and how orchard management affects soil properties, especially the contents and structure of soil organic matter during orchard development, and their further influences on neonicotinoid persistence. Here, surface soil samples were collected from the citrus orchards with different cultivation ages (1, 10, 14, and 20 years), and their physicochemical properties were determined. Changes in the chemical structure of soil organic matter (SOM) were furtherly examined using solid-state CP/TOSS ¹³C NMR. Then, the sorption isotherms of imidacloprid in these soils were investigated. The sorption coefficient (K_d) of imidacloprid at C_e of 0.05 mg/L in the orchard soils increased by 19.4-23.3%, along a 20-year chronosequence of cultivation, which should be mainly ascribed to the increase of SOM. However, the organic carbon-normalized sorption coefficient (K_oc, sorption per unit mass of OM) of imidacloprid declined with increasing cultivation ages. Moreover, the polar and aliphatic domains of SOM had a significantly positive relation to the K_oc of imidacloprid, suggesting its key role in governing imidacloprid sorption. The results highlighted that reasonable management measures could be adopted to control the occurrence and fate of neonicotinoids in soils, mainly by affecting the content and quality of SOM.

Natural aeolian dust particles have no substantial effect on atmospheric polycyclic aromatic hydrocarbons (PAHs): A laboratory study based on naphthalene

Natural aeolian dust (AD) particles are potential carriers of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. The heterogeneous interaction between them may lead to worsened air quality and enhanced cytotoxicity and carcinogenicity of ambient particulates in downwind areas, and this topic requires in-depth exploration. In this study, AD samples were collected from four Asian dust sources, and their physical properties and compositions were determined, showing great regional differences. The physical and chemical interactions of different AD particles with naphthalene (Nap; model PAH) were observed in aqueous systems. The results showed that AD particles from the Loess Plateau had weak adsorption to Nap, which was fitted by the Langmuir isotherm. There was no obvious adsorption to Nap found for the other three AD samples. This difference seemed to depend mainly on the specific surface area and/or the total pore volume. In addition, the Nap in the aqueous solution did not undergo chemical reactions under dark conditions and longwave ultraviolet (UV) radiation but degraded under shortwave UV radiation, and 2-formylcinnamaldehyde and 1,4-naphthoquinone were the first-generated products. The degradation of Nap in the aqueous solution was probably initiated by photoionization, and the reaction rate constant (between 1.44 × 10^-4 min^-1 and 8.55 × 10^-4 min^-1) was much lower than that of Nap with hydroxyl radicals. Instead of inducing or promoting the chemical change in Nap, the AD particles slowed photodegradation due to the extinction of radiation. Therefore, it is inferred that natural AD particles have no substantial effect on the transportation and transformation of PAHs in the atmosphere.