Biosorption of azo dyes by raspberry-like Fe3O4@yeast magnetic microspheres and their efficient regeneration using heterogeneous Fenton-like catalytic processes over an up-flow packed reactor

Raspberry-like Fe3O4@yeast composite microspheres, whose properties integrate the biosorption features of yeast cells with the excellent magnetic and catalytic properties of Fe3O4 nanoparticles were synthesized by a simple electrostatic-interaction-driven self-assembly heterocoagulation. They were successfully applied in an up-flow packed column for the removal of the model water contaminant methylene blue dye (MB) by consecutive bioadsorption-heterogeneous Fenton oxidation cycles. The as-synthesized Fe3O4@yeast composites were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), powder X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The adsorption process was controlled by the electrostatic interactions between the adsorbent and contaminant. The adsorbent is suitable for the adsorption of positively charged compounds at mildly acidic pH, neutral and alkaline pH, with the highest performance observed at alkaline pH. The experimental breakthrough curves measured at different influent MB concentration, flow rate, bed height and pH were modeled by the Yoon-Nelson model. The in-situ regeneration of the contaminant-loaded Fe3O4@yeast microspheres and their reuse in multiple cycles was demonstrated by triggering the heterogeneous Fenton-like reaction catalyzed by the supported magnetite. The raspberry-like Fe3O4@yeast magnetic microsphere should be a promising and practical adsorbent for removal and destruction of positively charged organic compounds in wastewater

The complete chloroplast genome sequences of two species from Nitraria

Nitraria tangutorum and N. roborowskii are the representative species of Nitraria and mainly distributed in the salt deserts regions of northwest China. In the current study, we report the complete sequences of the chloroplast genomes of N. tangutorum and N. roborowskii, which were 159,383 and 159,397 bp in length, respectively, with 112 predicted genes consisting of 79 protein-coding genes, 39 tRNA genes, and eight rRNA genes. The GC content of the two chloroplast genomes were 37.15% and 37.32% in N. tangutorum and N. roborowskii, respectively. ML phylogenomic analysis indicated that N. tangutorum and N. roborowskii formed one monophyletic group as the basal position of Sapindales clade and supporting separate this genus form Zygophyllaceae

Efficient Absorption of Antibiotic from Aqueous Solutions over MnO2@SA/Mn Beads and Their In Situ Regeneration by Heterogeneous Fenton-Like Reaction

Alginate has been extensively used as absorbents due to its excellent properties. However, the practical application of pure alginate has been restricted since the saturated adsorbent has weak physical structure and could not be regenerated easily. In this study, a low-cost and renewable composite MnO2@alginate/Mn adsorbent has been prepared facilely for the absorptive removal of antibiotic wastewater. FE-SEM, FTIR, and XRD analyses were used to characterize the samples. The norfloxacin (NOR) was used as an index of antibiotics. More specifically, the batch absorption efficiency of the adsorbents was evaluated by pH, contact time with different NOR concentration, and the temperature. Thus, the performance of absorption kinetic dynamics and isotherm equations were estimated for the adsorptive removal process. Parameters including ΔG0, ΔH0, and ΔS0 were utilized to describe the feasible adsorption process. To regenerate the saturated absorptive sites of the adsorbent, the heterogeneous Fenton-like reactions were trigged by introduction of H2O2. The results showed that the in situ regenerating has exhibited an excellent recycling stability. The high activity and the simple fabrication of the adsorbents make them attractive for the treatment of wastewater containing refractory organic compound and also provide fundamental basis and technology for further practical application

Adsorption Performance of Methyl Violet via α-Fe2O3@Porous Hollow Carbonaceous Microspheres and Its Effective Regeneration through a Fenton-Like Reaction

α-Fe2O3@porous hollow carbonaceous microspheres (α-Fe2O3@PHCMs) were prepared through a combination of hydrothermal and calcination method. The novel α-Fe2O3@PHCMs integrated the adsorptive and catalytic performances and served as an inexpensive adsorbent to rapidly remove cationic dye (methyl violet (MV)) from aqueous solution. Equilibrium studies indicated that the dye molecules obeyed Langmuir type of adsorption with the calculated maximum adsorption capacity of 539.8 mg∙g−1 at 313.15 K. Kinetic data were better described by pseudo-second-order model and the thermodynamic studies illustrated that MV adsorption onto the composite was spontaneous, endothermic and occurred by physisorption. The Fenton-like process was found to be effective for the regeneration of the spent α-Fe2O3@PHCMs. The regeneration efficiency, as high as 88.0%, was still maintained after three consecutive adsorption-regeneration cycles. FTIR and XRD characterizations of the composite before and after adsorption-regeneration treatment showed that the Fenton-like process did not cause serious damage to the structure of composites

Adsorption of Organic Dyes by TiO 2

TiO2@yeast-carbon microspheres with raspberry-like morphology were fabricated based on the pyrolysis method. The obtained products were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). Effects of initial dye concentration and contact time on adsorption capacity of TiO2@yeast-carbon for cationic dye methylene blue (MB) and anionic dye congo red (CR) were investigated. Experimental data were described by Langmuir, Freundlich, Temkin, and Koble-Corrigan isotherm models, respectively. It was found that the equilibrium data of MB adsorption were best represented by Koble-Corrigan, and CR adsorption was best described by both Freundlich and Koble-Corrigan isotherm models. The kinetic data of MB and CR adsorption fitted pseudo-second-order kinetic model well. The results demonstrated that TiO2@yeast-carbon microspheres achieved favorable removal for the cationic MB in comparison with that for the anionic CR. In addition, regeneration experimental results showed that TiO2@yeast-carbon exhibited good recycling stability, reusability, and in situ renewability, suggesting that the as-prepared TiO2@yeast-carbon might be used as the potential low cost alternative for recalcitrant dye removal from industrial wastewater. One possible mechanism for regenerating dye-loaded TiO2@yeast in situ was also proposed

Magnetic Fe3O4@Chitosan Carbon Microbeads: Removal of Doxycycline from Aqueous Solutions through a Fixed Bed via Sequential Adsorption and Heterogeneous Fenton-Like Regeneration

The adsorptive removal of antibiotics from aqueous solutions is recognized as the most suitable approach due to its easy operation, low cost, nontoxic properties, and high efficiency. However, the conventional regeneration of saturated adsorbents is an expensive and time-consuming process in practical wastewater treatment. Herein, a scalable adsorbent of magnetic Fe3O4@chitosan carbon microbeads (MCM) was successfully prepared by embedding Fe3O4 nanoparticles into chitosan hydrogel via an alkali gelation-thermal cracking process. The application of MCM composites for the adsorptive removal of doxycycline (DC) was evaluated using a fixed-bed column. The results showed that pH, initial concentration, flow rate, and bed depth are found to be important factors to control the adsorption capacity of DC. The Thomas and Yoon-Nelson models showed a good agreement with the experimental data and could be applied for the prediction of the fixed-bed column properties and breakthrough curves. More importantly, the saturated fixed bed can be easily recycled by H2O2 which shows excellent reusability for the removal of doxycycline. Thus, the combination of the adsorption advantage of chitosan carbon with catalytic properties of magnetic Fe3O4 nanoparticles might provide a new tool for addressing water treatment challenges

A novel and sensitive method for determining vitamin B3 and B7 by pre-column derivatization and high-performance liquid chromatography method with fluorescence detection - Fig 5

<p>The 3D response surface of peak area affected by varying derivatization temperature and time(a), varying derivatization temperature and EDC dosage (b), derivatization time and EDC dosage (c).</p

Novel Fabrication of Biodegradable Superabsorbent Microspheres with Diffusion Barrier through Thermo-Chemical Modification and Their Potential Agriculture Applications for Water Holding and Sustained Release of Fertilizer

Synergistic utilization of water and fertilizer has vital contribution to the modern production of agriculture. This work reports on a simple and facile strategy to prepare biodegradable yeast/sodium alginate/poly­(vinyl alcohol) superabsorbent microspheres with a diffusion barrier merit by thermo-chemical modification route. The integrated performances, including water absorbency, water retention, water evaporation ratio, leaching loss control, sustained-release behaviors, and degradation in soil, were systematically investigated. The results revealed that the modified microspheres were a triumphant water and fertilizer manager to effectively hold water and control the unexpected leakage of fertilizer for sustained release. Therefore, this work provides a promising approach to ameliorate the utilization efficiency of water and fertilizer in potential agriculture applications