Revelation of high-adsorption-performance activated carbon for removal of fluoroquinolone antibiotics from water

The preparation of carbonaceous sorbents can combine the use of waste material and the improvement of water quality. Six activated carbons prepared from different agricultural waste biomasses were tested for adsorption of norfloxacin and ofloxacin fluoroquinolone antibiotics from water. Activated carbons were prepared by conventional pyrolysis at 600 degrees C in a nitrogen atmosphere of ZnCl2-activated red mombin seeds (RMS), corn cob (CC), coffee husk (CH), internal and external parts of mango seeds (MSEP, MSIP), and ice cream beans (GS), which are widely available as agro-industrial biomass wastes in Latin America. The textural and surface properties of prepared activated carbons were thoroughly investigated, and the sorption mechanism was described through proper kinetic and adsorption isotherm models. Moreover, the molecular dimensions of norfloxacin and ofloxacin were estimated to consider the possible sterical shielding of micropores of the investigated activated carbons. Norfloxacin and ofloxacin were strongly adsorbed onto all investigated activated carbons. Adsorption kinetics fitted best to Elovich model; adsorption isotherms correlated best with Redlich-Peterson model. Maximum adsorption capacities, obtained from Langmuir model, were 404 mg.g(-1) for norfloxacin and 380 mg.g(-1) for ofloxacin. The best adsorption performance was observed for RMS-based activated carbon. A comparison of prepared materials led to the conclusion that high micropore volume and net pore volume are the determining properties of good adsorption performance in the case of removal of fluoroquinolone antibiotics from water.Web of Scienc

Candida parapsilosis Biofilm Identification by Raman Spectroscopy

Colonies of Candida parapsilosis on culture plates were probed directly in situ using Raman spectroscopy for rapid identification of specific strains separated by a given time intervals (up to months apart). To classify the Raman spectra, data analysis was performed using the approach of principal component analysis (PCA). The analysis of the data sets generated during the scans of individual colonies reveals that despite the inhomogeneity of the biological samples unambiguous associations to individual strains (two biofilm-positive and two biofilm-negative) could be made

The influence of structural properties on the adsorption capacities of microwave-assisted biochars for metazachlor removal from aqueous solutions

Biochars, carbonaceous materials prepared without the usage of chemical agents, are porous materials capable of adsorbing pollutants from ground-and surface waters. In this study, biochars prepared from various types of agricultural biomass were tested for the adsorptive removal of herbicide metazachlor from an aqueous environment. Banana wastes, red mombin seeds, corncob, cocoa pod husk, and coffee husk were used as precursors. Biochars were prepared with the aid of microwave treatment. The effect of precursor type on structure and adsorption was examined. Adsorption was controlled by a multistep mechanism, adsorption kinetics followed predominantly the pseudo-second-order model, adsorption isotherms suited to both Langmuir and Freundlich isotherms, depending on the particular biochar. Significant differences between the structural properties and adsorption capacities of the examined biochars were observed. The best adsorption properties for metazachlor uptake were observed for banana waste-based biochar, which had large, elongated pores, highest volume of micropores and one of the highest contents of polar functional groups. The maximum adsorption capacity, calculated from Langmuir isotherm, was 146.01 mg.g(-1), The adsorption capacity at equilibrium, obtained by kinetic measurements, was 27.25 mg.g(-1), the kinetic constant was 5.14.10- 3 dm3.min(-1) (both calculated from pseudo-second order model). Molecular modeling revealed that metazachlor molecules preferably entered two layer wide cavities containing one COOH group with their pyrazole rings.Web of Science103art. no. 10800