Magnetic anomalies of forest soils in the Upper Silesia-Northern Moravia region

Previous investigations revealed a strong magnetic anomaly due to soil magnetic enhancement in the industrialized cross-border area of Upper Silesia (Poland) and Northern Moravia (Czech Republic). Since industrial and urban dusts contain magnetic particles, this soil magnetic enhancement is assumed to be of anthropogenic origin, caused by a high concentration of atmospherically deposited magnetic particles, accumulated in topsoil layers. This assumption is proved by investigations of vertical profiles of magnetic susceptibility along a transect crossing the border area of the two countries. The results show that the population of magnetic minerals in the organic horizon is different from that in the mineral horizons. The vertical distribution of magnetic susceptibility and thermomagnetic analysis suggests negligible lithogenic contribution. The observed relationship between magnetic susceptibility and some heavy metals, confirmed by micromorphological observations and microchemical analysis of magnetic particles separated from the organic horizons of forest topsoil, has proved the usefulness of soil magnetometry for pollution study.     

Synthesized magnetic nanoparticles coated zeolite for the adsorption of pharmaceutical compounds from aqueous solution using batch and column studies

The contamination of fresh water with pharmaceutical and personal care products (PPCPs) has risen during the last few years. The adsorption of some PPCPs namely, Diclofenac-Na, Naproxen, Gemfibrozil and Ibuprofen from aqueous solution has been studied, magnetic nanoparticles coated zeolite (MNCZ) has been used as the adsorbent. Batch adsorption experiment was conducted to study the influences of different adsorption parameters such as contact time, solution pH and PPCPs concentrations in order to optimize the reaction conditions. The removal was favored at low pH values. Thus, as pH turns from acidic to basic conditions these compounds were less efficiently removed. The initial concentration does not appear to exert a noticeable effect on the removal efficiency of the studied PPCPs at low concentrations, but it showed less removal efficiency during high concentration of PPCPs especially for Ibuprofen. The removal of Diclofenac-Na was independent on time, while the contact time was of significant effect on the adsorption of Naproxen, Gemfibrozil and Ibuprofen even though these compounds were removed up to 95% during 10 min using MNCZ. From the isotherm adsorption study, the adsorption of PPCPs studied on MNCZ was best fitted with Freundlich isotherm equation. Pseudo-second order model providing the best fit model with the experimental data. Column adsorption study was conducted to compare the removal efficiency of MNCZ with other processes used at drinking water treatment plants (DWTPs), MNCZ showed high removal efficiency (>99%) than other used processes at DWTPs.     

镁铝水滑石衍生复合氧化物的COS水解性能

采用共沉淀的方法制备了系列镁铝水滑石衍生复合氧化物,分别考察了煅烧温度、反应温度、水蒸气体积分数以及碱金属添加对材料COS水解反应活性的影响.通过X射线衍射仪(XRD)、气体吸附仪(BET)、程序升温脱附(TPD)和X射线光电子能谱(XPS)等对复合氧化物的晶体结构、比表面积、孔结构和碱性位分布等进行表征.结果表明,水解反应活性随煅烧温度的增加先升高后减小,650℃煅烧制备的复合氧化物材料具有最佳的水解反应活性(COS完全转化的维持时间为180min).反应温度的升高有利于水解活性的提高,从70℃起水解反应就具有很高的活性和稳定性.此外,Cs的添加有利于水解反应活性的提高,掺杂后材料COS完全转化的维持时间达到了480 min.     

Comparison of different combined treatment processes to address the source water with high concentration of natural organic matter during snowmelt period

The source water in one forest region of the Northeast China had very high natural organic matter (NOM) concentration and heavy color during snowmelt period. The efficiency of five combined treatment processes was compared to address the high concentration of NOM and the mechanisms were also analyzed. Conventional treatment can hardly remove dissolved organic carbon (DOC) in the source water. KMnO₄ pre-oxidization could improve the DOC removal to 22.0%. Post activated carbon adsorption improved the DOC removal of conventional treatment to 28.8%. The non-sufficient NOM removal could be attributed to the dominance of large molecular weight organic matters in raw water, which cannot be adsorbed by the micropore upon activated carbon. O₃ + activated carbon treatment are another available technology for eliminating the color and UV₂₅₄ in water. However, its performance of DOC removal was only 36.4%, which could not satisfy the requirement for organicmatter. The limited ozone dosage is not sufficient to mineralize the high concentration of NOM. Magnetic ion-exchange resin combined with conventional treatment could remove 96.2% of color, 96.0% of UV₂₅₄ and 87.1% of DOC, enabling effluents to meet the drinking water quality standard. The high removal efficiency could be explained by the negative charge on the surface of NOM which benefits the static adsorption of NOM on the anion exchange resin. The results indicated that magnetic ion-exchange resin combined with conventional treatment is the best available technology to remove high concentration of NOM.     

Separation/degradation behavior and mechanism for cationic/anionic dyes by Ag-functionalized Fe3O4-PDA core-shell adsorbents

● PDA-Fe₃O₄-Ag was made by hydrothermal and oxidation self-polymerization method. ● PDA-Fe₃O₄-Ag had great magnetic separation performance. ● PDA-Fe₃O₄-Ag had good adsorption and degradation performance for ionic dyes. ● PDA-Fe₃O₄-Ag showed NR and MO degradation potential of 91.2% and 87.5%, respectively. High-performance adsorbents have been well-studied for the removal of organic dye pollutants to promote environment remediation. In this study, an Ag nanoparticle-functionalized Fe₃O₄-PDA nanocomposite adsorbent (PDA-Fe₃O₄-Ag) was synthesized, and the adsorption/separation performance of commonly used cationic and anionic organic dyes by the PDA-Fe₃O₄-Ag adsorbent were assessed. Overall, PDA-Fe₃O₄-Ag exhibited a significantly higher adsorption capacity for cationic dyes compared to anionic dyes, the highest of which was more than 110.0 mg/g (methylene blue (MB)), which was much higher than not only the adsorption capacities of the anionic dyes in this study but also other dye adsorption capacities reported in the literature. The dye adsorption kinetics data fitted well to both the pseudo second-order kinetics model and the Langmuir isotherm model, suggesting a monolayer-chemisorption-dominated adsorption mode. Thermodynamics analysis indicated that the adsorption process was both endothermic and spontaneous. Furthermore, the PDA-Fe₃O₄-Ag adsorbent achieved high photodegradation removal rates of the dyes, especially neutral red (NR) and methyl orange (MO), which were 91.2% and 87.5%, respectively. With the addition of PDA-Fe₃O₄-Ag, the degradation rate constants of NR and MO increased from 0.08 × 10⁻² and 0 min⁻¹ to 2.11 × 10⁻² and 1.73 × 10⁻² min⁻¹, respectively. The high adsorption and photocatalytic degradation performance of the PDA-Fe₃O₄-Ag adsorbent make it an excellent candidate for removing cationic and anionic dyes from the industrial effluents.     

Weak magnetic field accelerates chromate removal by zero-valent iron

Weak magnetic field(WMF) was employed to improve the removal of Cr(VI) by zero-valent iron(ZVI) for the first time. The removal rate of Cr(VI) was elevated by a factor of 1.12–5.89 due to the application of a WMF, and the WMF-induced improvement was more remarkable at higher Cr(VI) concentration and higher p H. Fe2+was not detected until Cr(VI) was exhausted, and there was a positive correlation between the WMF-induced promotion factor of Cr(VI) removal rate and that of Fe2+release rate in the absence of Cr(VI) at pH 4.0–5.5. These phenomena imply that ZVI corrosion with Fe2+release was the limiting step in the process of Cr(VI) removal. The superimposed WMF had negligible influence on the apparent activation energy of Cr(VI) removal by ZVI, indicating that WMF accelerated Cr(VI)removal by ZVI but did not change the mechanism. The passive layer formed with WMF was much more porous than without WMF, thereby facilitating mass transport. Therefore,WMF could accelerate ZVI corrosion and alleviate the detrimental effects of the passive layer, resulting in more rapid removal of Cr(VI) by ZVI. Exploiting the magnetic memory of ZVI, a two-stage process consisting of a small reactor with WMF for ZVI magnetization and a large reactor for removing contaminants by magnetized ZVI can be employed as a new method of ZVI-mediated remediation.     

Coupling magnetic particles with flocculants to enhance demulsification and separation of waste cutting emulsion for engineering applications

Magnetic particles were coupled with a flocculant to enhance the demulsification and separation of waste cutting emulsions. The optimal magnetic particle size and critical magnetic field conditions were investigated to achieve large-scale engineering application of magnetic demulsification separation for waste cutting emulsion treatment. The micro-scale magnetic particles were found to show comparable effects to nano-scale magnetic particles on enhancing the demulsification and separation of cutting emulsions, which are beneficial for broadening the selectivity of low-cost magnetic particles. The critical magnetic separation region was determined to be an area 40 mm from the magnetic field source. Compared to the flocculant demulsification, the magnetic demulsification separation exhibited a significant advantage in accelerating flocs–water separation by decreasing the separation time of flocs from 180–240 min to less than 15 min, compressing the flocs by reducing the floc volume ratio from 60%–90% to lower than 20%, and showing excellent adaptability to the variable properties of waste cutting emulsions. Coupled with the design of the magnetic disk separator, continuous demulsification separation of the waste cutting emulsion was achieved at 1.0 t/hr for at least 10 hr to obtain clear effluent with 81% chemical oxygen demand removal and 89% turbidity reduction. This study demonstrates the feasibility of applying magnetic demulsification separation to large-scale continuous treatment of waste emulsion. Moreover, it addresses the flocs–water separation problems that occur in practical flocculant demulsification engineering applications.     

220kV输电线路导线不同排列方式下电磁环境影响分析

从220 kV高压架空输电线路工程的导线不同排列方式入手,分析不同导线排列方式下输电线路产生的电磁环境影响,通过对相同电压等级的同塔四回路输电线在导线水平排列和垂直排列两种方式下对周围电磁环境影响的比较分析,探讨此两种导线排列方式对周围环境的影响程度。同时,通过预测输电线路在导线相同排列方式下不同相序布置时对周围环境的影响,对今后的高压输电线路架线方式从减小环境影响角度考虑提出建议。     

A nanocomposite consisting of silica-coated magnetite and phenyl-functionalized graphene oxide for extraction of polycyclic aromatic hydrocarbon from aqueous matrices

In this study,graphene oxide was covalently immobilized on silica-coated magnetite and then modified with 2-phenylethylamine to give a nanocomposite of type Fe_3O_4@SiO_2@GO-PEA that can be applied to the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons(PAHs) from water samples.The resulting microspheres(Fe_3O_4@SiO_2@GO-PEA) were characterized by Fourier transform-infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),CHNS elemental analysis,and vibrating sample magnetometry(VSM) techniques.The adsorbent possesses the magnetic properties of Fe_3O_4 nanoparticles that allow them easily to be separated by an external magnetic field.They also have the high specific surface area of graphene oxide which improves adsorption capacity.Desorption conditions,extraction time,amount of adsorbent,salt concentration,and pH were investigated and optimized.Following desorption,the PAHs were quantified by gas chromatography with flame ionization detection(GC-FID).The limits of detection(at an S/N ratio of 3) were achieved from 0.005 to0.1 μg/L with regression coefficients(R~2) higher than 0.9954.The relative standard deviations(RSDs) were below 5.8%(intraday) and 6.2%(inter-day),respectively.The method was successfully applied to the analysis of PAHs in environmental water samples where it showed recoveries in the range between 71.7%and 106.7%(with RSDs of 1.6%to 8.4%,for n = 3).The results indicated that the Fe_3O_4@SiO_2@GO-PEA microspheres had a great promise to extraction of PAHs from different water samples.     

Removal of Cs from water and soil by ammonium-pillared montmorillonite/Fe3O4 composite

To remove cesium ions from water and soil, a novel adsorbent was synthesized by following a one-step co-precipitation method and using non-toxic raw materials. By combining ammonium-pillared montmorillonite (MMT) and magnetic nanoparticles (Fe₃O₄), an MMT/Fe₃O₄ composite was prepared and characterized. The adsorbent exhibited high selectivity of Cs⁺ and could be rapidly separated from the mixed solution under an external magnetic field. Above all, the adsorbent had high removal efficiency in cesium-contaminated samples (water and soil) and also showed good recycling performance, indicating that the MMT/Fe₃O₄ composite could be widely applied to the remediation of cesium-contaminated environments. It was observed that the pH, solid/liquid ratio and initial concentration affected adsorption capacity. In the presence of coexisting ions, the adsorption capacity decreased in the order of Ca^2 + > Mg^2 + > K⁺ > Na⁺, which is consistent with our theoretical prediction. The adsorption behavior of this new adsorbent could be expressed by the pseudo-second-order model and Freundlich isotherm. In addition, the adsorption mechanism of Cs⁺ was NH₄⁺ ion exchange and surface hydroxyl group coordination, with the former being more predominant.