Electro-migration of heavy metals in an aged electroplating contaminated soil affected by the coexisting hexavalent chromium

Cr(VI) was often reported to oxidize soil organic matter at acidic environments due to its high ORP, probably thus changing cationic metal species bound to soil organic matter, and influencing their electro-migration patterns. However, such an effect on the electro-migration was not confirmed in most previous studies. Therefore, this study applied a fixed voltage direct current field on an aged electroplating contaminated clayed soil, with a special interest in the direct or indirect influence of Cr(VI) on the electro-migration of other coexisting metals. After 353 h electrokinetic process, 81% of Zn, 53% of Ni and 22% of Cu in the original soil were electro-migrated into the electrolyte, and most of the remaining concentrated near the cathode. The Cr(VI) oxidized some soil organic matter along its migration pathway, with a pronounced reaction occurred near the anode at low pHs. The resulting Cr(III) reversed its original movement, and migrated towards the cathode, leading to the occurrence of a second Cr concentration peak in the soil. Metal species analyses showed that the amount of metals bound to soil organic matter significantly decreased, while a substantial increase in the Cr species bound to Fe/Mn (hydro-)oxides was observed, suggesting an enhancement of cationic metal electro-migration by the reduction of Cr(VI) into Cr(III). However, the Cr(VI) may form some stable lead chromate precipitates, and in turn demobilize Pb in the soil, as the results showed a low Pb removal and an increase in its acid-extractable and residual fractions after electrokinetic remediation.     

Short-term effect of aniline on soil microbial activity: a combined study by isothermal microcalorimetry, glucose analysis, and enzyme assay techniques

The accidents of aniline spill and explosion happened almost every year in China, whereas the toxic effect of aniline on soil microbial activity remained largely unexplored. In this study, isothermal microcalorimetric technique, glucose analysis, and soil enzyme assay techniques were employed to investigate the toxic effect of aniline on microbial activity in Chinese soil for the first time. Soil samples were treated with aniline from 0 to 2.5 mg/g soil to tie in with the fact of aniline spill. Results from microcalorimetric analysis showed that the introduction of aniline had a significant adverse effect on soil microbial activity at the exposure concentrations ≥0.4 mg/g soil (p?<?0.05) and ≥0.8 mg/g soil (p?<?0.01), and the activity was totally inhibited when the concentration increased to 2.5 mg/g soil. The glucose analysis indicated that aniline significantly decreased the soil microbial respiratory activity at the concentrations ≥0.8 mg/g soil (p?<?0.05) and ≥1.5 mg/g soil (p?<?0.01). Soil enzyme activities for β-glucosidase, urease, acid-phosphatase, and dehydrogenase revealed that aniline had a significant effect (p?<?0.05) on the nutrient cycling of C, N, and P as well as the oxidative capacity of soil microorganisms, respectively. All of these results showed an intensively toxic effect of aniline on soil microbial activity. The proposed methods can provide toxicological information of aniline to soil microbes from the metabolic and biochemical point of views which are consistent with and correlated to each other.     

污泥浓度对微孔曝气氧传质过程的影响

污泥浓度是影响微孔曝气氧传质过程的重要因素之一。在小试及中试规模上,研究了不同污泥浓度对微孔曝气氧传质过程的影响,得出曝气性能随污泥浓度的变化规律。结果表明,当污泥浓度低于2000mg／L时,曝气性能随浓度的增大而增强,在2000～3000mg／L时,KLa达到最大值;当污泥浓度大于2000～3000mg／L时,曝气性能随污泥浓度增大而降低,当污泥浓度大于5000mg／L时,曝气性能急剧降低。这一规律对于在设计和运行中合理确定污水处理中的污泥浓度,在达到处理效果的前提下,尽量降低电耗具有重要意义。     

活性染料K-2BP、KN-B和KN-R在椰壳活性炭上的脱色性能

开展椰壳活性炭对活性染料K-2BP、KN-B和KN-R的吸附脱色研究。发现K-2BP、KN-B和KN-R在该型活性炭上的吸附脱色率均随初始pH值的降低、温度的升高、染料初始浓度的降低、活性炭用量的增加以及NaCl盐度的增加而增加。在pH=7和T=25℃下,K-2BP、KN-B和KN-R在活性炭上的等温吸附规律符合Langmuir模型方程,最大饱和吸附量Qmax分别为263.15、256.41和250 mg/g,吸附自由能△G298 K分别为-10.632、-3.783和-2.805 kJ/mol;该条件下K-2BP、KN-B和KN-R的动力学吸附规律均符合准一级动力学吸附方程。等温吸附研究和吸附动力学研究均表明,相同条件下3种活性染料在该型活性炭上的吸附效果由高到低的顺序为:K-2BP>KN-B>KN-R。     

鸡毛不溶解蛋白海绵膜的制备与表征

通过冷冻干燥,将羽毛还原法残渣制成表面光滑、有弹性、孔隙致密、柔韧性高的海绵膜,不需预处理也无需添加交联剂,并通过傅立叶红外光谱仪(FTIR)、扫描电镜(SEM)、元素分析、示差扫描量热仪(DSC)和透气性测量仪对膜进行表征。在最佳甘油含量下,膜均匀平整,在160℃以内性质稳定,透气量368 mm/s,在医药、生物、纺织、环境及日化领域都具有很大的应用潜力。     

Comparisons of ambient air particulates concentrations (TSP,PM2.5) and dry depositions during smog and non-smog periods at Luliao,Shalu District sampling site

The concentrations of ambient total suspended particulates (TSP) and PM_2.5, and the dry depositions at a sample site at Luliao Junior High School (Luliao) in central Taiwan were measured during smog and non-smog days between December 2017 and July 2018. The results are compared to those obtained during non-smog periods in the years 2015–2017. The mean TSP and PM_2.5 concentrations and dry deposition flux were 72.41?±?26.40, 41.88?±?23.51?μg/m³, and 797.57?±?731.46?μg/m² min, respectively, on the smog days. The mean TSP and PM_2.5 concentrations and dry deposition flux on the non-smog days were 56.39?±?18.08, 34.81?±?12.59?μg/m³ and 468.93?±?600.57?μg/m² min, respectively. The mean TSP concentration in the smog period was 28% greater than that in the non-smog period, and the mean PM_2.5 concentration was 20% higher. The mean dry deposition flux in the smog period was 70% higher than that in the non-smog period at Luliao. The PM_2.5 concentrations exceeded the standards set by the Taiwan EPA (35?μg/m³ daily, and 15?μg/m³ annually). Therefore, the TSP and PM_2.5 concentrations and dry deposition must be reduced in central Taiwan on smog days. In addition, atmospheric TSP and PM_2.5 concentrations at various sampling sites were compared, and those herein were not higher than those measured in other countries. Finally, apart from the local traffic emissions, during smog periods, the other pollution source originated from the transportation process of traffic pollutants emitted in the northwest side of Taiwan.     

Ambient Air Particulates Bound Mercury Hg(p) Study Among Four Crops (Rice,White Cabbage,Arden Lettuce,and Gynura) at a Characteristic Sampling Site

The main purpose of this study was to monitor ambient air particulates and particulate-bound Hg (Hg[p]) compositions in different crops in the coastal zone in the Taichung, Taiwan, area at a sampling site during 2013 October to 2013 December. In addition, a direct mercury analyzer (DMA-80) was used to directly detect the concentration with measured results by the regression equation of Hg in the ambient air. The results indicated that: 1) the mean values of ambient air Hg(p) compositions in rice displayed no significant differences for weeks one, two, and three versus those of the other crops (white cabbage, Arden lettuce, and Gynura procumbens); 2) for white cabbage, the higher the humidity, the lower the average ambient air Hg(p) compositions that were obtained, a phenomenon that was also reflected on the crops of white cabbage and G. procumbens; 3) Arden lettuce displayed no significant differences in the leaf Hg(p) compositions during weeks one, two, and three; however, the stem portions displayed significant differences in Hg(p) compositions during weeks two and three; and 4) the Spearman statistical method showed the mean differences for ambient air Hg(p) at the Long-jing sampling site (coastal regions) with four different crops (rice, white cabbage, Arden lettuce, and Gynura) in central Taiwan. The results further revealed no significant differences in mean values.     

羽毛不可溶角蛋白海绵膜对Cr（Ⅵ）的吸附性能

通过冷冻干燥,将还原法产生的凝胶状不可溶蛋白制备成具有致密孔隙的海绵膜,无需预处理和无交联剂,并研究了其对Cr（Ⅵ）的吸附性能。结果表明,在60℃、固液比12．5g／L、初始浓度100mg／L下最大吸附量为148．8mg／g,吸附过程符合Langmuir型和Freundlich型等温吸附模型,为吸热过程,物理吸附和化学吸附均起到重要作用。     

吡啶改性膨润土对直接耐晒翠蓝染料废水脱色性能研究

为了解决日益严重的水污染问题,用吡啶作改性剂,对膨润土进行有机改性,制得一种新型水处理剂,用于直接耐晒翠蓝染料废水的处理。研究了处理废水的最佳工艺条件。结果表明,投土量为10g／L,pH=3．5,搅拌速度为175r／min,搅拌时间25rain,离心时间为2min,吡啶改性土对直接耐晒翠蓝染料废水的脱色率可达80％。改性土对直接耐晒翠蓝的吸附过程可用准二级速率方程较好地描述。     

重庆市清水溪河流沉积物重金属污染及潜在生态风险评价

采用单因子指数法和Hakanson潜在生态风险指数法,通过分析清水溪流域18个采样点沉积物中典型重金属污染物Cd、Cr、Cu、Pb和Zn的含量,定量确定了清水溪沉积物中重金属的污染程度和潜在生态风险程度。结果表明,清水溪流域污染非常严重,上中游河段受到重金属的高强度污染,主要的重金属污染因子为Zn,污染因子的高低顺序为：Zn>Cu>Cr>Cd>Pb;潜在生态风险指数RI平均值为255.58,清水溪处于高值潜在生态风险,且上中游河段潜在生态风险指数很高,主要的潜在生态风险因子为Cd,潜在生态风险因子的大小顺序为：Cd>Cu>Cr>Zn>Pb。