Efficient treatment of palladium from wastewater by acrolein cross-linked chitosan hydrogels: Adsorption, kinetics, and mechanisms.

Herein we present a study on the preparation and properties of a hydrogel adsorbent for treatment of wasted palladium souring from actial petrochemical industrial wastewater. Chitosan was used as the raw material and acrolein as the cross-linking agent for the hydrogel (A/CS). The adsorption behaviors of the hydrogel for Pd(II) ions were characterized and analyzed. The effect of pH, temperature, adsorption kinetics, and thermodynamics were investigated. Langmuir models were employed to describe the adsorption isotherms, while the pseudo-second-order equation was applied to describe the adsorption kinetics. The experimental results demonstrated that the adsorption was a monolayer chemical adsorption, and the adsorption capacity was found to reach 505.05 mg/g under optimal conditions. In addition, FT-IR and XPS analyses, combined with MS calculations confirmed that chelation and electrostatic attraction were dominated in the adsorption process. Overall, the development of this hydrogel adsorbent will provide a practical approach to the treatment of industrial wastewater containing palladium and have great potential for practical applications.

Efficient selective recycle of acid blue 93 by NaOH activated acrolein/chitosan adsorbent via size-matching effect.

Here we report an efficient strategy to separate and recycle acid blue 93 (AB93) from mixed anionic dyes selectively within sodium hydroxide activated A/CS adsorbent (N-A/CS). This work broke the common sense that the larger the specific surface area, the better the adsorption property is, which provided an alternative strategy to separate dyes. The adsorption equilibrium of AB93 could be achieved approximately within 1-2 min, and the maximum adsorption capacity was up to 2500 mg/g. Besides, it can be activated continuously and reused at least 15 times. In mixed anionic dyes, the adsorption selectivity of N-A/CS on AB93 in the mixture of AB93 and acid fuschin (AF) reached up to 99.7 %. Molecular dynamics simulation revealed that the trend of adsorption energy for dyes qualifies well with the experimental order of adsorption capacities and molecular sizes among five anionic dyes based on molecular matching effect. Thus, N-A/CS is a low-cost, easily-preparable, significantly-effective-and-reusable adsorbent, providing a promising "size-matching" strategy to adsorb multi-component dye systems.

In-situ Raman study on kinetics behaviors of hydrated bubble in thickening.

Natural gas leakage by means of bubbles in cold seep abundantly existed on the ocean floor, causing the change of ocean ecology and the increase of atmospheric temperature. Fortunately, hydrated bubbles as a way of methane sequestration can reduce the effect on the ocean ecology and the escape of gas bubbles from the ocean floor, and are getting attention. To know the growth mode and efficiency of gas hydrate sequestration on bubble, the thickening growth kinetics of hydrated bubble was studied in present work. In-situ Raman spectroscopy was used to analyze the evolution of gas pores and mass transfer channels in the sI CH4, sI CH4-C2H6 and sII CH4-C2H6 hydrate films on the hydrated bubble by the peak area ratio of Raman spectra. Three types of Raman spectra (a-, b-, and c-type), three texture structures of film (Large gas pore; Small gas pore; No gas pore) and two hydrate thickening patterns (filling of new hydrate within large gas pores; covering growth on the original hydrate lattice) were provided in the thickening of hydrated bubble. Results showed that the thickening of the hydrated bubble was a multi-stages growth, i.e., quick growth (stage I), slow growth (stage II), and no growth (stage III). The texture structures and the type and size of gas pore in hydrated bubble were critical for the kinetics growth rate of hydrated bubble in thickening. Especially, the theory of heterogeneous growth of hydrated bubble was proposed to apply the hydrate growth at the interface of two or multi- bubbles, accelerating the efficiency of carbon sequestration as the hydrated bubble. This study will provide a better theoretical basis for understanding the behaviors and efficiency of hydrated carbon sequestration on the surface of bubbles resulting from the gas leakage in the hydrate exploitation or the natural cold seep. SYNOPSIS: Hydrated bubble strongly modulates the emission of a potent greenhouse gas from the deep sea.

Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy.

The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15 K), as determined by the stable C-H region Raman peaks and AL/AS value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to small cavities) being around 3.0. However, it was reduced at higher temperatures (271.15 K and 272.15 K), as shown from the dramatic change in Raman spectra and fluctuations in AL/AS values. The self-preservation effect for methane-ethane double hydrate is observed at temperatures lower than 271.15 K. The structure transition from sI to sII occurred during the methane-ethane hydrate decomposition process, which was clearly identified by the shift in peak positions and the change in relative peak intensities at temperatures from 269.15 K to 271.15 K. Further investigation shows that the selectivity for self-preservation of methane over ethane leads to the structure transition; this kind of selectivity increases with decreasing temperature. This work provides new insight into the kinetic behavior of hydrate dissociation below the ice point.

Ultrasound estimation of female bladder volume based on magnetic resonance modeling.

PURPOSE: We developed a precise method to noninvasively and conveniently measure female bladder volume greater than 100 ml by ultrasound. MATERIALS AND METHODS: Using the proposed method bladder magnetic resonance measurements were made in 7 healthy women to create the volume estimation model. To validate the model for ultrasound application bladder ultrasound images were scanned in 23 healthy women and corresponding volumes were calculated. Calculated and true volumes were compared with the Pearson correlation coefficient and Bland-Altman plots. RESULTS: A total of 51 bladder magnetic resonance images were segmented and reconstructed as 3-dimensional objects. Of the 51 objects 24 had a volume of greater than 100 ml. Based on the 24 objects we regressed the new equation, V = 7.1 x Dl x H - 23, where V represents estimated volume, Dl represents bladder depth and H represents bladder height measured by the proposed method. The estimation was statistically significant (SE 44, r(2) 0.94, p <0.001). A total of 69 ultrasound measurements were made and corresponding volumes were calculated by the equation. The sum of voided and post-void residual volume, when there was any, was considered true volume (range 140 to 995 ml). A significant relationship was found between true and calculated volume (mean difference -3 ml, mean absolute difference 23, r(2) = 0.97, p <0.01). The Bland-Altman 95% limits of agreement were -57 to 51 ml. CONCLUSIONS: The proposed method performs well to estimate female bladder volume greater than 100 ml.