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As an important part of lake and reservoir ecosystem, sediment is an important "source" and "sink" of pollutants. Antibiotics, as a kind of important emerging organic pollutants, have attracted global attention. In order to understand the adsorption behavior and mechanism of antibiotics in sediment, enrofloxacin (ENR) was used as the target pollutant to evaluate its adsorption behavior in sediment and soil and the response mechanism of environmental factors by using the intermittent equilibrium method. The results showed that the adsorption equilibrium time of ENR in sediment and soil was 6 h, and the adsorption kinetics was in line with the quasi-second-order kinetics. The two-compartment model Herry-Langmuir can better describe the adsorption of ENR by sediment and soil. There is a lag phenomenon in desorption process.The average lag coefficient HI of sediment and soil was 1.08 × 10−3 and 0.43 × 10−3, respectively, indicating that ENR was difficult to be released. When pH = 5, the adsorption capacity is the highest, indicating that the adsorption mechanism of ENR in the sample is mainly cation exchange; the higher the cationic valence state of the background liquid is, the stronger the competitive adsorption capacity is, which leads to the gradual decrease of ENR adsorption capacity in the sample. Because ENR contains -F group, resulting in complex reaction with Al3+ in the solution, thus reducing the activity of Al3+, reducing the competitive adsorption of Al3+ and ENR, then ENR adsorption capacity increased. The change of ENR adsorption capacity of sediment and soil is Q(Al3+)>Q(Na+)>Q(K+)>Q(Ca2+)>Q(Mg2+)>Q(Fe3+). The adsorption capacity of ENR on sediment was higher than that on soil under all conditions. [ABSTRACT FROM AUTHOR]

The main objective of this work was to study the adsorption characteristics of Cd by adding corn stover biochar and saline-alkali soil after freezing and thawing, and the saline-alkali land in Lesheng Town, Da'an City, Jilin Province was selected as the model/representative area. The artificially simulated freezing and thawing environments was conducted in the experiments. After the soil is incubated, adsorption experiments were carried out. FTIR spectra analysis indicated that biochar amendment increased the aromatic contents of the soil. Moreover, the results showed that regardless of biochar amendment, the freezing-thawing could increase hydroxyl, carboxyl, and aromatic hydrocarbon contents. In contrast, freezing-thawing reduced the soil pH, cation exchange capacity, conductivity, and exchangeable sodium (regardless of biochar amendment). In all cases, Cd adsorption isotherms and kinetic curves were best fit by the Langmuir equation and quasi-second-order kinetic equation, respectively, and the thermodynamic parameters of Cd adsorption (ΔG < 0, ΔH > 0, and ΔS > 0) suggested that the process was consistently spontaneous, endothermic, and disordered. A significant increase in soil Cd adsorption capacity was observed in the with increasing pH. [ABSTRACT FROM AUTHOR]

Due to the norfloxacin will enter the natural water body with the effluent of the sewage treatment plant and cause water environment pollution, the research on how to effectively remove norfloxacin has become a hot topic. This experiment used hydrochloric acid and sodium hydroxide to study the modification of fly ash. The structure characteristics and properties of modified fly ash were determined by scanning electron microscope, X-ray diffractometer and infrared spectrometer, and the adsorption process of norfloxacin by fly ash was analyzed. It was found that the surface of fly ash modified by acid and alkali was rougher and the voids increased, which provided a rich adsorption site for the adsorption reaction of norfloxacin on fly ash, moreover, the specific surface area of sodium hydroxide modified fly ash increased the most, and the ability to adsorb norfloxacin was the strongest. The adsorption process characteristics showed that the adsorption reaction of norfloxacin is spontaneous, exothermic, disordered, and when the temperature increased, the adsorption amount of norfloxacin by fly ash was decreased, and the adsorption effect of fly ash on norfloxacin was the strongest under the pH = 7.0, yet inhibited when the adding of Ca2+ in the solution. [ABSTRACT FROM AUTHOR]

The levels of enrofloxacin have exceeded acceptable standards in the water environment of many global regions, and the problem of pollution caused by enrofloxacin needs to be solved urgently. In this study, phosphoric acid and potassium hydroxide were used to modify corn stalk biochar. The properties and structure of the modified biochar were studied by scanning electron microscopy, infrared spectrometer, X-ray diffraction spectroscopy, and other analytical methods. Other factors influencing enrofloxacin adsorption were assessed using the equilibrium adsorption method. The surface area of the acid- and alkali-modified biochar was found to increase 10- and 14-fold, respectively. The equilibrium adsorption capacity of enrofloxacin on the acid- and alkali-modified biomass carbon increased by 27.80% and 54.08%, respectively. The quasi-second-order kinetic equation and Langmuir equation described the adsorption process of the biochars accurately. At pH = 5.0, the biochars had the highest levels of enrofloxacin adsorption. The adsorption of enrofloxacin onto the biochars negatively correlated with the concentration of Ca2+ in the background solution. [ABSTRACT FROM AUTHOR]