Mihua Shao

Spatial distribution and risk assessment of heavy metals in sediments of Shuangtaizi estuary, China.

In order to evaluate the spatial distribution and potential ecological risk of Pb, Cu, Zn, Cd, and Hg, the surface sediments were collected from 18 sites in the Shuangtaizi estuary. The concentrations of Pb, Cu, Zn, Cd, and Hg were analyzed by atomic absorption spectrophotometry and atomic fluorescence spectrometry after digestion. The particle sizes of the sediments were analyzed using a laser diffraction particle size analyzer. The results show that the heavy metal contents in the sediments are observed in the following order: Zn (18.25-126.75mg/kg)>Pb (4.38-9.65mg/kg)>Cu (1.80-17.68mg/kg)>Cd (0.241-0.764mg/kg)>Hg (0.007-0.021mg/kg). In comparison with the concentrations of heavy metals in other regions, the concentrations of Pb, Cu, and Zn in the Shuangtaizi estuary are generally low, and the Cd concentrations are close to those reported in other regions. Both the potential ecological risk index and the geoaccumulation index reveal that the heavy metal pollution in Shuangtaizi estuary is mainly dominated by Cd.

Assessment of Heavy Metal Contamination in the Sediments of the Shuangtaizi Estuary Using Multivariate Statistical Techniques

ABSTRACT In order to assess heavy metal pollution of sediment samples collected from Shuangtaizi estuary, contamination factor (CF) and multivariate statistical analyses, including principal component analysis (PCA), cluster analysis (CA) and correlation analysis, are carried out in this paper. CF confirms that Pb, Cu and Hg concentrations are very low and all fall within the range of background, while Zn and Cd demonstrate moderate contamination (in A10, A13, A15, A16 and A17 sites) and very high contamination (in A10, A13, A15 and A17 sites), respectively. The PCA indicates that four significant principal components (PCs) are extracted, explaining 88.959% of total variance, which suggests that Pb, Cu and Zn are mainly associated with organic carbon (OC). The result from CA is consistent with that obtained from PCA, classifying that the heavy metals in two clusters derive from different sources. Correlation analysis supports the conclusions from PCA and CA, elucidating the relationships between heavy metals and particle sizes of the sediments.

Coal-Based Carbon Membrane Coupled with Electrochemical Oxidation Process for the Enhanced Microalgae Removal from Simulated Ballast Water

A treatment system combining the coal-based carbon membrane with electrochemical oxidation process was designed for the enhanced microalgae removal from simulated ballast water. The effects of various parameters including microalgae species, microalgae density, electric field intensity, and electrical conductivity on the separation performance were carried out. Fouling test was further performed for assessing the antifouling ability of the treatment system. The results showed big microalgae species tended to form a thick fouling layer on the carbon membrane, resulting in low permeate flux. High microalgae density gave rise to serious membrane fouling, which decreases the permeate flux. The treatment system showed enhanced permeate flux and fouling resistance by coupling with electrochemical oxidation process. High conductivity favored the electrochemical reactions on the surface of the carbon membrane, which reduces the clogging of the microalgae to the carbon membrane. After cleaning, the treatment system still kept high permeate flux, implying its good regeneration ability.

Morphologically controlled synthesis of porous Mn2O3 microspheres and their catalytic applications on the degradation of methylene blue

AbstractPorous Mn2O3 microspheres are controllably synthesized by selectively etching MnCO3 precursor with HCl solution. Morphologies and microstructures of Mn2O3 microspheres are analyzed by SEM, TEM, XRD, and N2 sorption technique. The catalytic performances of Mn2O3 microspheres for the degradation of methylene blue (MB) are investigated, and the reaction kinetics of MB degradation is also studied. The results show it is feasible to control the morphologies of Mn2O3 microspheres by adjusting the concentration of HCl solution, and the well-developed porous Mn2O3 microspheres demonstrate good potential on MB degradation. The degradation reactions follow the pseudo-first-order kinetic model, and the degradation capabilities for MB are great dependent on BET surface areas and pore volumes of Mn2O3 microspheres.

Enhanced Treatment Ability of Membrane Technology by Integrating an Electric Field for Dye Wastewater Treatment: A Review

The increasing environmental awareness and stricter regulations have prompted the developments of various treatment technologies for dye wastewater. Membrane separation receives extensive attention as a promising technology because of many advantages. However, higher removal performance requirements and membrane fouling issues make a single separation method inadequate for the removal of dyes from industrial wastewater. Exerting an electric field on membrane separation system for dye wastewater treatment has already been proposed and newly developed in recent years because each technology complements the advantages and overcomes the challenges of the other. Although the amount of literature in this field is limited, this integrated technology has exhibited good performance on dye removal and is believed to have a bright prospect. This review mapped out the previous studies and current trends as well as provided a prospective outlook for advances in various membrane-combining technologies with an electric field, especially with the electric advanced oxidation processes. The different combination patterns, performance evaluations, removal mechanisms, and treatment parameters are gathered and discussed.