Jianyou Long

Simultaneous removal of thallium and chloride from a highly saline industrial wastewater using modified anion exchange resins

Simultaneous removal of thallium (Tl) and chloride from a highly saline industrial wastewater was investigated using modified anion ion exchange resins. The removal of thallium was mainly driven by the exchange of Tl-chlorocomplex (TlCl4-) formed in the oxidation of thallous (Tl (I)) to thallic ion (Tl (III)) by hydrogen peroxide (H2O2) under saline conditions. Over 97% of thallium and chloride removal was achieved using the modified resins, with a wide optimal conditions found to be H2O2 dosage 1.0-25.0mL/L, pH 1.6-4.3, and flow rate 0.5-4.7mL/L. The modified resins had an exchange capacity of 4.771mg Tl/g dry resins for thallium and 1800mg Cl/g dry resins for chloride. Stable regeneration could be achieved with the modified resins: over 97% of thallium and 90% of chloride can be eluted using Na2SO3 solution and alternating hot (60°C) H2SO4 and cold (25°C) water, and over 98% removal of thallium and chloride was achieved after five consecutive regeneration cycles.

Removal of thallium from aqueous solutions using Fe-Mn binary oxides

In this study, Fe-Mn binary oxides, which harbor the strong oxidative power of manganese dioxide and the high adsorption capacity of iron oxides, were synthesized for Tl(I) removal using a concurrent chemical oxidation and precipitation method. The adsorption of Tl onto the Fe-Mn adsorbent was fast, effective, and selective, with equilibrium sorption reaching over 95% under a broad operating pH (3-12), and high ionic strength (0.1-0.5mol/L). The adsorption can be well fitted with both Langmuir and Freundlich isotherms, and the kinetics can be well described by the pseudo-second-order model. Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) spectra suggest that surface complexation, oxidation and precipitation were the main mechanisms for the removal of Tl. This study shows that the Fe-Mn binary oxides could be a promising adsorbent for Tl removal.

Synthesis of FC-supported Fe through a carbothermal process for immobilizing uranium

The abundant generation of uranium (U), a radioactive nuclide, engenders a severe hazard to the environment. Iron based materials were used to immobilize U from water, however, the immobilization is limited by the agglomeration of nanoparticle Fe. In this study, a novel carbothermal process was proposed to synthesize flour carbon (FC) supported nano-flake Fe (Fe-FC). Scanning electron microscopy (SEM) and nitrogen isotherm adsorption-desorption analysis were conducted to characterize Fe-FC. The immobilization characteristics were investigated through batch sorption experiments. Results indicated that nano-flake was appropriately dispersed on the surface. The sorption capacity reached 19.12 mg/g when the initial concentration of U and the dosage of Fe-FC were 20 mg/L and 1 g/L, respectively. Langmuir isotherm sorption and pseudo-second-order models were fitted well to sorption experimental data. The sorption mechanism is ascribed to surface chemisorptions between U(VI) and Fe-FC. Subsequently, X-ray diffraction (XRD) analysis validated that formation of Fe2UO3 contributed to the favorable immobilization of U and that Fe2UO3 was the fate of U.

Fractional distribution of thallium in paddy soil and its bioavailability to rice

To investigate the bioavailability of thallium (Tl) in soil and rice in a Tl-contaminated area in Guangdong, China, the topsoil and rice samples were collected from 24 sampling sites and analyzed. Moreover, a modified sequential extraction procedure was applied to determine the different Tl fractions in the soil. The mean pH value of the soil samples was 4.50. The total Tl concentration in the paddy soil was about 4-8 times higher than the Canadian guideline value (1mgkg-1) for agricultural land uses. The mean ecological risk index of Tl was determined to be 483, indicating that potential hazard of the paddy soil was serious. The mean content of Tl in rice was 1.42mgkg-1, which exceeded the German maximum permissible level (0.5mgkg-1) of Tl in foods and feedstuffs by a factor of nearly 3. The hazard quotient value via rice intake was 57.6, indicating a high potential health risk to the local residents. The distribution of various Tl fractions followed the order of easily reducible fraction (40.3%) > acid exchangeable fraction (30.5%) > residual fraction (23.8%) > oxidizable fraction (5.4%). Correlation analyses showed that the easily reducible fraction correlates positively with the soil Fe and Mn contents, whereas the acid exchangeable fraction is significantly correlated with the S content. The soil pH was negatively correlated with the Tl content in both soil and rice. The Tl content in rice was more strongly correlated with the exchangeable fraction than the total Tl content in the soil. Overall, the bioavailability of Tl in more acidic soil is higher, and is strongly dependent on the speciation of Tl, especially the content of acid exchangeable fraction.

Shape-dependent adsorption of CeO 2 nanostructures for superior organic dye removal

Highly efficient removal of dye pollutants from water resources remains a great challenge. Herein, we demonstrate a new approach for the efficient removal of anionic organic dyes from wastewater using shape-dependent CeO2 nanostructures. It was found that the volume stoichiometry ratio of ethanol to water (EtOH/H2O) was a key factor affecting the CeO2 nanostructures. Accordingly, the adsorption capacity of the spindle CeO2 nanostructure for Congo red reached 162.4 mg g-1, which is much higher than that of octahedral and spherical CeO2 or other adsorbents previously reported. The superior adsorption performance may be mainly attributed to the peculiar structure and presence of electrostatic interactions between the sample surface and dye molecules. This finding will provide new avenues for using promising adsorbent materials for dye removal in water treatments.

Enhancement production of qinlingmycin by a soil- derived Streptomyces No. 24 using protoplast fusion technology and assessment of antibacterial activity

This study was aimed at improving qinlingmycin production by protoplast fusion technology for Streptomyces No. 24 and mutant strain Ms-24. In the protoplast preparation, the optimal glycine concentration, lysozyme concentration and lytic time were 0.25%, 1 mg/ml and 1 h, respectively. In the process of protoplast fusion, the weight of polyethylene glycol (PEG) molecule had little effect, while the top fusion efficiency was observed at 50% PEG. By protoplast fusion, the three high qinlingmycin producing fusants Pf77, pf126 and pf138 were fortunately obtained from 163 fusant strains. In vitro antibacterial activities of the three fusants than Streptomyces No. 24 were increased by 43.48, 60.87 and 65.22%, respectively. The results by HPLC detection analysis showed qinlingmycin productions of the fusants fermented broths were increased by 36.59, 74.39 and 91.46%, respectively, than that of Streptomyces No. 24. The fusants showed good heredity stability in continuing transferred ten generations test. Key words : Protoplast fusion, Streptomyces No. 24, mutant Ms-24, qinlingmycin, antibacterial activity