RESUMEN
Residual antibiotics in water are often persistent organic pollutants. The purpose of this study was to prepare a cellulose nanocrystals/graphene oxide composite (CNCs-GO) with a three-dimensional structure for the removal of the antibiotic levofloxacin hydrochloride (Levo-HCl) in water by adsorption. The scanning electron microscope, Fourier transform infrared (FT-IR), energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and other characterization methods were used to study the physical structure and chemical properties of the CNCs-GO. The three-dimensional structure of the composite material rendered a high surface area and electrostatic attraction, resulting in increased adsorption capacity of the CNCs-GO for Levo-HCl. Based on the Box-Behnken design, the effects of different factors on the removal of Levo-HCl by the CNCs-GO were explored. The composite material exhibited good antibiotic adsorption capacity, with a removal percentage exceeding 80.1% at an optimal pH of 4, the adsorbent dosage of 1.0 g l-1, initial pollutant concentration of 10.0 mg l-1 and contact time of 4 h. The adsorption isotherm was well fitted by the Sips model, and kinetics studies demonstrated that the adsorption process conformed to a quasi-second-order kinetics model. Consequently, the as-synthesized CNCs-GO demonstrates good potential for the effective removal of antibiotics such as levofloxacin hydrochloride from aqueous media.
RESUMEN
Developing an efficient adsorption material is of great significance for application in wastewater contaminated with pesticides. The present study investigated a promising nanomaterial (PhaCNCs) prepared with nanocellulose by grafting polyvinylamine for adsorption chlorpyrifos (CP). Structures and characteristics of PhaCNCs were analyzed using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). Central composite design based on response surface methodology was used to optimize adsorption process of CP by PhaCNCs. The optimum chemometric showed that 0.57 g L-1 PhaCNCs adsorbed 36.81 mg L-1 CP to yield an efficiency of 92.72 %. The results indicated that the adsorption process was well-described by the pseudo-second-order model. Langmuir isotherm calculated the maximum adsorption capacity for CP of 98.116 mg g-1, implied that the adsorption capacity of PhaCNCs was significantly higher than other adsorbents. This study will contribute to the development of adsorption processes for CP removal from aqueous environments.
RESUMEN
An exciting electrochemical oxidation (EO) process has been developed. Compared with electro-Fenton (EF) and electro-coagulation (EC) processes, this process had more advantages in the degradation of methylene blue. It is observed that methylene blue can be quickly degraded by EO, in which an iron rod is used as an anode, graphite is used as a cathode, and fly ash-red mud particles are used as particle electrodes. Compared to EC and EF processes that are affected by specific pH values, EO has excellent performance in the pH range of 3.0-11.0. In addition, the electric energy consumption (EEC) of EF, EC and EO is 81.51, 36.55 and 21.35 kW h m-3 respectively, suggesting EO is more economical. The free radical scavenging mechanism of i-PrOH is studied, and the contribution of EC, EF and fly ash-red mud particle electrodes in EO is inferred. Particle electrodes before and after use are characterized by SEM, EDS and BET to illustrate the role of particle electrodes in the EO system. Analysis of flocs and solutions by FTIR and GC-MS proves that EO can effectively degrade methylene blue, and the degradation route of methylene blue is speculated. The particle electrode dissolution experiment shows that the prepared fly ash-red mud particle electrode is considered to be suitable and safe for wastewater treatment. Finally, in actual surface water experiments, the EO process still has great potential.
RESUMEN
Choosing an electrode material with good performance and low cost is of great significance for the practical application of the electro-Fenton process. In this study, graphite felt was systematically studied to determine its application performance in an electro-Fenton system. The influence of operating parameters, pH and voltage, on the H2O2 yield and the evolution of iron ions was investigated, which helped to select the optimal parameter values. The removal rate of methylene blue was 97.8% after 20 min electrolysis under the conditions of 7 V voltage and pH 3. Inhibition experiments showed the graphite felt E-Fenton system mainly relied on the indirect oxidation of ·OH and the direct oxidation of the graphite felt anode to degrade the methylene blue. The graphite felt showed good stability as a cathode during repeated use, but the anode conductivity and catalytic performance were decreased, and the adsorption performance was enhanced. Finally, the graphite felt electrode was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS) to preliminarily analyze the reason for the change in anode performance.
RESUMEN
To study the detection of weak D and Del from samples initially screened RhD(-), RhD phenotype was initially screened by routine serological test, out of which weak D phenotype was detected by indirect antiglobulin test (IAT) and Del phenotype was detected by chloroform-trichloroethylene absorption-elution test. The results showed that 56 samples were RhD(-) confirmed by routine serology test, which were screened out of 26 200 donors, among them 5 samples were typed as weak D by IAT and 9 cases samples were typed as Del by absorption-elution test. In conclusion, the samples which typed as RhD(-) by routine serological test must be identified by IAT and chloroform-trchloroethylene absorption test is order to detect weak D and Del phenotype. It is important for clinical transfusion safely.
