A Theoretical Study of the Adsorption Process of B-aflatoxins Using Pyracanthakoidzumii (Hayata) Rehder Biomasses.

Employing theoretical calculations with density functional theory (DFT) using the B3LYP/6-311++G(d,p) functional and basis set, the interaction of the aflatoxin B1 (AFB1) molecule and the functional groups present in the Pyracantha koidzumii biosorbent was investigated. Dissociation free energy and acidity equilibrium constant values were obtained theoretically both in solution (water) and gas phases. Additionally, the molecular electrostatic potential for the protonated molecules was calculated to verify the reactivity. Thus, methanol (hydroxyl group), methylammonium ion (amino group), acetate ion (carboxyl group), and acetone (carbonyl group), were used as representatives of the substrates present in the biomass; these references were considered using the corresponding protonated or unprotonated forms at a pH value of 5. The experimental infrared spectrophotometric data suggested the participation of these functional groups in the AFB1 biosorption process, indicating that the mechanism was dominated by electrostatic interactions between the charged functional groups and the positively charged AFB1 molecule. The theoretical determination indicated that the carboxylate ion provided the highest interaction energy with the AFB1 molecule. Consequently, an enriched biosorbent with compounds containing carboxyl groups could improve the yield of the AFB1 adsorption when using in vitro and in vivo trials.

Biosorption of B-aflatoxins Using Biomasses Obtained from Formosa Firethorn [Pyracantha koidzumii (Hayata) Rehder].

Mycotoxin adsorption onto biomaterials is considered as a promising alternative for decontamination without harmful chemicals. In this research, the adsorption of B-aflatoxins (AFB1 and AFB2) using Pyracantha koidzumii biomasses (leaves, berries and the mixture of leaves/berries) from aqueous solutions was explored. The biosorbent was used at 0.5% (w/v) in samples spiked with 100 ng/mL of B-aflatoxin standards and incubated at 40 °C for up to 24 h. A standard biosorption methodology was employed and aflatoxins were quantified by an immunoaffinity column and UPLC methodologies. The biosorbent-aflatoxin interaction mechanism was investigated from a combination of zeta potential (ζ), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The highest aflatoxin uptakes were 86% and 82% at 6 h using leaves and the mixture of leaves/berries biomasses, respectively. A moderate biosorption of 46% was attained when using berries biomass. From kinetic studies, the biosorption process is described using the first order adsorption model. Evidence from FTIR spectra suggests the participation of hydroxyl, amine, carboxyl, amide, phosphate and ketone groups in the biosorption and the mechanism was proposed to be dominated by the electrostatic interaction between the negatively charged functional groups and the positively charged aflatoxin molecules. Biosorption by P. koidzumii biomasses has been demonstrated to be an alternative to conventional systems for B-aflatoxins removal.

[Characteristics of foliar delta13C values of common shrub species in various microhabitats with different karst rocky desertification degrees].

By measuring the foliar delta13C values of 5 common shrub species (Rhamnus davurica, Pyracantha fortuneana, Rubus biflorus, Zanthoxylum planispinum, and Viburnum utile) growing in various microhabitats in Wangjiazhai catchment, a typical karst desertification area in Guizhou Province, this paper studied the spatial heterogeneity of plant water use at niche scale and the response of the heterogeneity to different karst rocky desertification degrees. The foliar delta13C values of the shrub species in the microhabitats followed the order of stony surface > stony gully > stony crevice > soil surface, and those of the majority of the species were more negative in the microhabitat soil surface than in the others. The foliar delta13C values decreased in the sequence of V. utile > R. biflorus > Z. planispinum > P. fortuneana > R. davurica, and the mean foliar delta13C value of the shrubs and that of typical species in various microhabitats all increased with increasing karst rocky desertification degree, differed significantly among different microhabitats. It was suggested that with the increasing degree of karst rocky desertification, the structure and functions of karst habitats were impaired, microhabitats differentiated gradually, and drought degree increased.

Assessment of cationic dye biosorption characteristics of untreated and non-conventional biomass: Pyracantha coccinea berries.

This work reports on the assessment of the dye methylene blue biosorption properties of Pyracantha coccinea berries under different experimental conditions. Equilibrium and kinetic studies were carried out to determine the biosorption capacity and rate constants. The highest biosorption yield was observed at about pH 6.0, while the biosorption capacity of the biomass decreased with decreasing initial pH values. Batch equilibrium data obtained at different temperatures (15, 25, 35 and 45 degrees C) were modeled by Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. Langmuir isotherm model fitted the equilibrium data, at the all studied temperatures, better than the other isotherm models indicating monolayer dye biosorption process. The highest monolayer biosorption capacity was found to be 127.50mg/g dry biomass at 45 degrees C. Kinetic studies indicate that the biosorption process followed the pseudo-second-order model, rather than the pseudo-first-order model. DeltaG degrees , DeltaH degrees and DeltaS degrees parameters of biosorption show that the process is spontaneous and endothermic in nature. The biosorbent-dye interaction mechanisms were investigated using a combination of Fourier transform infrared spectroscopy and scanning electron microscopy. The biosorption procedure was applied to simulated wastewater including several pollutants. The results obtained indicated that the suggested inexpensive and readily available biomaterial has a good potential for the biosorptive removal of basic dye.