Yongqian Fu

Novel magnetic chitosan/poly(vinyl alcohol) hydrogel beads: preparation, characterization and application for adsorption of dye from aqueous solution.

Novel magnetic chitosan/poly(vinyl alcohol) hydrogel beads (m-CS/PVA HBs) were prepared by an instantaneous gelation method and characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA). Results of characterization indicated that m-CS/PVA HBs have been prepared successfully without damaging the crystal structure of Fe(3)O(4) and their saturation magnetization were about 21.96 emu g(-1). The adsorption capacity of Congo Red on the m-CS/PVA HBs was 470.1 mg g(-1). The adsorption was well described by pseudo-second-order kinetics and Langmuir equation. Positive value of enthalpy change (ΔH(∘)) (13.32 kJ mol(-1)) showed that the adsorption was endothermic and physical in nature. The values of Gibbs free energy change (ΔG(∘)) were found to be -3.321 kJ mol(-1) at 298 K for m-CS/PVA HBs, indicating the spontaneity of Congo Red adsorption. Therefore, the m-CS/PVA HBs could be employed as a low-cost alternative to other adsorbents in the removal of dyes from aqueous solution.

Effective decolorization of congo red in aqueous solution by adsorption and photocatalysis using novel magnetic alginate/γ-Fe2O3/CdS nanocomposite

AbstractMagnetic alginate/γ-Fe2O3/CdS composite photocatalyst (m-alginate/Fe2O3/CdS composite) was synthesized via a simple hydrothermal method, and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and vibrating sample magnetometer (VSM). The photocatalytic activity of m-alginate/Fe2O3/CdS composite was evaluated via the adsorption-photocatalytic removal of aqueous organic dye, i.e. congo red (CR). The m-alginate/Fe2O3/CdS composite can be easily manipulated and separated by a magnetic field, leading to the convenience and feasibility in the removal of aqueous hazardous dye. In addition, the kinetics of photocatalysis of CR has also been performed and found to follow the pseudo-first-order kinetics. These results suggest that m-alginate/Fe2O3/CdS composite can be used as an effective photocatalyst for the removal of hazardous pollutants such as dyes, and the adsorption-photocatalysis of these organic contaminants in wastewater effluents can s...

High-efficiency l-lactic acid production by Rhizopus oryzae using a novel modified one-step fermentation strategy.

In this study, lactic acid fermentation by Rhizopus oryzae was investigated using the two different fermentation strategies of one-step fermentation (OSF) and conventional fermentation (CF). Compared to CF, OSF reduced the demurrage of the production process and increased the production of lactic acid. However, the qp was significantly lower than during CF. Based on analysis of μ, qs and qp, a novel modified OSF strategy was proposed. This strategy aimed to achieve a high final concentration of lactic acid, and a high qp by R. oryzae. In this strategy, the maximum lactic acid concentration and productivity of the lactic acid production stage reached 158g/l and 5.45g/(lh), which were 177% and 366% higher, respectively, than the best results from CF. Importantly, the qp and yield did not decrease. This strategy is a convenient and economical method for l-lactic acid fermentation by R. oryzae.

Equilibrium and Kinetic studies on adsorption of methyl orange from aqueous solution on chitosan/kaolin/γ-Fe 2 O 3 nanocomposite

Adsorption of anionic azo dye methyl orange (MO) on chitosan/kaolin/ γ-Fe<inf>2</inf>O<inf>3</inf> nanocomposite from aqueous solutions was investigated in a batch system with respect to adsorbent dosage and initial pH. The pseudo-first-order, pseudo-secondorder kinetic models and intra-particle diffusion model were used to evaluate the kinetic data and the rate diffusion model constants were calculated. Results of the kinetic studies showed that MO dye onto chitosan/kaolin/γ-Fe<inf>2</inf>O<inf>3</inf> nanocomposite was better described by the pseudo-second-order kinetic model. The Langmuir isotherm provided the better correlation for MO adsorption onto chitosan/kaolin/γ-Fe<inf>2</inf>O<inf>3</inf> nanocomposite. The maximum adsorption capacities were 36.67 and 35.27 mg g⁻¹ for MO adsorption at 310 and 320 K.

Effects of Calcium on the Morphology of Rhizopus oryzae and L-lactic Acid Production

The effects of exogenous calcium on fungal pellet morphology during preculture and L-lactic acid production were studied. The results showed that addition of exogenous calcium could induce pellet formation. The diameter of the pellet increased with increasing concentration of exogenous calcium, including CaCl2 and CaCO3. The smaller pellet precultured with low concentration of soluble calcium (CaCl2) was beneficial for L-lactic acid production because the pellet was dense and the large inner part of the pellet was inactive. By contrast, the larger pellet precultured with high concentration of insoluble calcium (CaCO3), except 8.0 g/L CaCO3, was beneficial for L-lactic acid production. Supported by the CaCO3 powder, the entire biomass layer was fully active, and the highest L-lactic acid productivities of 1.22 g/L h and 58.6 g/L L-lactic acid were reached using the 1.5 mm pellet.