Environmental Science and Pollution Research - Many parts of the vehicle cabin generate volatile organic compounds (VOCs), and some are hazardous and/or odorous to humans. In this study, VOCs in... 相似文献
Sodium citrate (SC) is a widely-used food and industrial additive with the properties of complexation and microbial degradation. In the present study, nano-zero-valent iron reaction system ([email protected]) was successfully established by modifying nanoscale zero-valent iron (nZVI) with SC and biochar (BC), and was employed to remove Cr(Ⅵ) from aqueous solutions. The nZVI, SC-nZVI and [email protected] were characterized and compared using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyses (TGA), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that nZVI was successfully loaded on the biochar, and both the agglomeration and surface passivation problems of nanoparticles were well resolved. The dosage of SC, C:Fe, initial pH and Cr(Ⅵ) concentration demonstrated direct effects on the removal efficiency. The maximum Cr(Ⅵ) removal rate and the removal capacity within 60 min were 99.7% and 199.46 mg/g, respectively (C:Fe was 1:1, SC dosage was 1.12 mol.%, temperature was 25°C, pH = 7, and the original concentration of Cr(Ⅵ) was 20 mg/L). The reaction confirmed to follow the pseudo-second-order reaction kinetics, and the order of the reaction rate constant k was as follows: [email protected] > [email protected] > SC-nZVI > nZVI. In addition, the mechanism of Cr(Ⅵ) removal by [email protected] mainly involved adsorption, reduction and co-precipitation, and the reduction of Cr(Ⅵ) to Cr(Ⅲ) by nano Fe0 played a vital role. Findings from the present study demonstrated that the [email protected] exhibited excellent removal efficiency toward Cr(Ⅵ) with an improved synergistic characteristic by SC and BC. 相似文献
Phosphogypsum (PG) is one of solid wastes with large amount of yield and serious pollution, which has attracted wide attention. The aim of this study is to investigate filling performance of PG on polypropylene (PP) or high-density polyethylene (HDPE) matrix. In this work, PG was calcined initially to improve whiteness and fix impurities. X-ray diffraction (XRD) results showed that after calcined at 500 °C, the PG phase changed from CaSO4·2H2O to CaSO4. The modification effects of the three modifiers were evaluated by Fourier transform infrared spectra (FTIR), oil absorption value, water floatability, and contact angle analysis. The effects of weight fraction of PG in PP and HDPE matrix on mechanics and morphology were observed by tensile test, impact test, and scanning electron microscope. Scanning electron microscope (SEM) showed that modified PG can be dispersed uniformly in the matrix at low filling content. With the increase of PG filling content, the analysis of mechanical properties showed that the tensile strength of HDPE matrix increased, while the tensile strength of PP matrix decreased gradually. The impact strength of HDPE matrix would decrease, but the impact strength of PP matrix increased first and then decreased. Compared with calcium carbonate (CC), the mechanical properties of HDPE filled with PG performed better. The apparent density showed that polymer composites filled with PG have the characteristics of light weight.
As an ubiquitous carcinogen, polycyclic aromatic hydrocarbons (PAHs) are closely related to anthropogenic activities. The process of urbanization leads to the spatial interlacing of farmlands and urbanized zones. However, field evidence on the influence of urbanization on the accumulation of PAHs in crops of peri-urban farmlands is lacking. This study comparatively investigated the urbanization-driven levels, compositions, and sources of PAHs in 120 paired plant and soil samples collected from the Yangtze River Delta in China and their species-specific human intake risks. The concentrations of PAHs in crops and soils in the peri-urban areas were 2407.92 ng g?1 and 546.64 ng g?1, respectively, which are significantly higher than those in the rural areas. The PAHs in the root were highly relevant to those in the soils (R2?=?0.63, p?<?0.01), and the root bioconcentration factors were higher than 1.0, implying the contributions of root uptake to plant accumulations. However, the translocation factors in the peri-urban areas (1.57?±?0.33) were higher than those in the rural areas (1.19?±?0.14), indicating the enhanced influence through gaseous absorption. For the congeners, the 2- to 3-ring PAHs showed a higher plant accumulation potential than the 4- to 6-ring PAHs. Principal component analysis show that the PAHs in the peri-urban plants predominantly resulted from urbanization parameters, such as coal combustion, vehicle emissions, and biomass burning. The mean values of estimated dietary intake of PAHs from the consumption of peri-urban and rural crops were 9116 ng day?1 and 6601.83 ng day?1, respectively. The intake risks of different crops followed the order rice?>?cabbage?>?carrot?>?pea. Given the significant input of PAHs from urban to farmland, the influence of many anthropogenic pollutants arising from rapid urbanization should be considered when assessing the agricultural food safety.
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