Sorption Behavior and Mechanism of Pb(II) on Chinese Loess

Lead pollution is common in Western China and has caused serious public health problems recently. The treatment of wastewater containing Pb(II) is stringent for the sustainable development of local economics. The Chinese loess proved effective to remove Pb(II) from aqueous solution and applicable in the treatment of wastewater from lead–zinc ore mining sites. The adsorption capacity of Chinese loess about Pb(II) is determined as high as 270.26?mg?g?1 in this study. Factors affecting the adsorption of Pb(II) include slurry concentration, solution pH, temperature, and equilibrating duration. The optimum conditions for Pb(II) adsorption include sorbent dosage ≥ 0.05?g/50?mL, pHi ≥ pHzpc, temperature = 55°C, and equilibration duration ≥ 30?min. The isotherms and kinetic data are well fitted with Langmuir model and pseudo-first order kinetics, respectively. The thermodynamic behavior reveals the exothermic and spontaneous nature of the adsorption. The adsorption of Pb(II) on loess involves chemical reaction with calcite and surface complexation with clay minerals and hydrolysis of quartz; the former is considered as the dominant mechanism. X-ray diffraction and Fourier transform infrared patterns confirmed these speculations.     

Synthesis of Long Afterglow Photoluminescent Materials Sr_2MgSi_2O_7∶Eu~(2 ), Dy~(3 ) by Sol-Gel Method

Withtheprogressofsocialcivilizationanddevel opmentofmodernscienceandtechnology ,thedemandforluminescentmaterialskeepsincreasingduetoitsgreatsocialandeconomicbenefits .Therefore ,prepa rationofluminescentmaterialswasregardedbypeopleveryearly .Asanembellish…     

Cu2+、Cd2+、Cr6+胁迫对斑马鱼抗氧化酶活性的影响

[目的]研究Cu<'2+>、Cd<'2+>、Cr<'6+>对斑马鱼抗氧化酶活性影响,探讨重金属对斑马鱼毒性大小.[方法]以斑马鱼为模式生物,采用半静态法对斑马鱼进行驯养和试验,测定Cu<'2+>、Cd<'2+>和Cr<'6+>对超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性影响.[结果]Cu<'2+>暴露1d胁迫斑马鱼SOD和CAT为诱导效应,胁迫POD为抑制-诱导-抑制效应,Cu<'2+>暴露7 d胁迫斑马鱼SOD为诱导效应,胁迫POD和CAT为抑制效应;Cu<'2+>和Cr<'6+>暴露1 d和7 d胁迫斑马鱼SOD和CAT均为诱导效应,胁迫POD为抑制效应.且暴露1 d和暴露7 d酶活性变化均显著.[结论]Cu<'2+>、Cd<'2+>、Cr<'6+>单一胁迫斑马鱼抗氧化系统酶活性变化显著,在短时间和低浓度暴露下,Cr<'6+>毒性作用最显著;在短时间中、高浓度暴露下,Cu<'2+>毒性作用最显著;长时间暴露时,Cu<'2+>毒性作用最强,可为重金属污染对水生生物毒性机理研究提供参考.     

石墨炉原子吸收光谱法测定钨粉及三氧化钨中微量铅、镉

本文研究了用酒到石酸络合基体元素钨，在不加基体改进剂的情况下，用标准加入法直接测定钨粉及三氧化钨中微量铅，锌的方法，铅，镉的检出限分别为2．6ng/ml和0.11ng/ml，回收率分别90％－115％和93％－113％之间，相对标准偏差均小于10％。     

剩余污泥裂解灰陶粒吸附酸性矿山废水中Zn2+、Cu2+、Pb2+性能及机理

以剩余污泥裂解灰为主要原材料,按照剩余污泥裂解灰︰膨润土︰淀粉为6︰3︰1的比例混合,经过造粒、熟化、干燥,最后于1 050 ℃氮气气氛下煅烧60 min制备多孔陶瓷颗粒。采用SEM-EDS、XRD表征陶粒吸附酸性矿山废水中Zn2+、Cu2+、Pb2+前后的微观形貌、元素变化及晶体结构。结果表明,所制备陶粒表面粗糙,具有大量孔隙结构。当陶粒投加量为3 g,初始pH=3.2,反应时间24 h时,制备的剩余污泥裂解灰陶粒对于Zn2+、Cu2+、Pb2+ 去除率分别达到99.2 0%、85.1 0%、96.27%。初始pH为中性时陶粒吸附效果优于酸性条件。陶粒对于Cu2+、Pb2+的吸附过程符合准二级动力学模型,以离子交换为主;对于Zn2+,准一级与准二级动力学模型均能较好拟合,物理吸附与化学吸附发挥同等重要作用。陶粒吸附过程均符合Freundlich等温模型,对于Cu2+的吸附主要发生在非均相活性位点,对于Zn2+和Pb2+的吸附既可以发生在均相单层也可以发生在非均相活性位点。利用剩余污泥裂解灰制备多孔陶瓷颗粒,不仅可以用于酸性矿山废水中处理重金属离子,还能解决污泥处置的问题,达到以废治污的目的。     

Attenuation of Roadway-Derived Heavy Metals by Wood Chips

Wood chips were evaluated for their ability to attenuate heavy metals in roadway runoff. Column experiments with controlled synthetic runoff composition and flow rate were used to assess effects of flow rate (intercepted sheetflow from a 3-m wide roadway section), runoff salt concentration, wood exposure to alternating wetting and drying cycles, wood aging, competition among dissolved heavy metals, and removal of particle-associated heavy metals. Overall, wood chips damped the “pulse” of copper in the synthetic runoff such that the effluent was characterized by lower concentrations (3–25% of input) over longer periods of time, but with little retention of the total copper mass. The most effective treatment was wood chips aged up to 9 months. Increased aging and chip water content reduced effluent concentrations, relative to no treatment. Flow rate had no effect on effluent concentrations. The presence of salt (>2?mS/cm) or dissolved lead (500?μg/L) in the runoff caused greater copper effluent concentrations than the no treatment case. Removal of suspended particles (and associated contaminants) was greater than 85% with an estimated capacity of 0.16?g/gwood. Field evaluation with concentrated flow to a gutter containing a wood chip treatment showed little effect on total or dissolved copper and zinc runoff concentrations and indicated that wood chips may be a source of contaminants in subsequent storm events. Applications of wood chips to treat roadway runoff would not provide a significant decrease in total maximum daily load contributions (e.g., kg/d); however, there may be some scenarios for which wood chip treatments to decrease peak storm water concentrations of dissolved heavy metals in sheetflow runoff is desirable.     

Hydrothermal preparation and persistence characteristics of nanosized phosphor SrS：Eu^2＋,Dy^3＋

Nanosized long-persistent phosphors SrS: Eu2+, Dy3+ were prepared by the hydrothermal method. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and charge-coupled device spectrometry. The persistence characteristic was studied using the decay curves. The results showed that the emission intensity decreased sharply with temperature increasing, although the particle size increased. The S2- vacancies caused by oxidization served as shallow traps, and Dy3+ served as deep traps in SrS: Eu2+, Dy3+. The afterglow intensity of SrS: Eu2+, Dy3+ was higher than that of SrS: Eu2+ prepared at the same temperature. However, the minimization span of initial afterglow with temperature for the former sample was larger than that for the latter. Binary-doped phosphor decayed more slowly than the singly doped one. The afterglow of SrS: Eu2+, Dy3+ decayed more quickly with the increase of sintering temperature.     

Effects of Cd2+, Pb2+ and CH3Hg+ on high voltage-activated calcium currents in pheochromocytoma (PC12) cells: potency, reversibility, interactions with extracellular Ca2+ and mechanisms of block

The present study attempted to determine the relationship between affective disposition and the favorability of letters of reference. We hypothesized that individuals with positive dispositions would write more favorable letters than would individuals with less positive or neutral dispositions. In addition, we also hypothesized that length of letter would partly mediate the relationship between affective disposition and letter favorability. To test these hypotheses, two studies were conducted. In order to present letter writers with a controlled stimulus, Study 1 entailed having 110 undergraduate students write letters of reference for two hypothetical job candidates in a laboratory setting. In order to test the generalizability of the laboratory study, Study 2 involved 95 faculty members who submitted three recent letters of reference they had written. Results showed that affective disposition was related to the favorability of letters of reference in both studies. Results also revealed that length of letter partly mediated the relationship between affective disposition and letter favorability. Copyright 1998 Academic Press.     

Impact of Salinity on MS-2 Sorption in Saturated Sand Columns—Fate and Transport Modeling

This research investigated the sorption and transport of MS-2 in saturated sand under a wide range of salinities using one-dimensional column experiments. The salinity varied from 0 ppt (fresh water) to 30 ppt. The MS-2 in the fresh water showed very weak adsorption due to having the same negative charge as the sand. Increasing the salinity concentrations dramatically enhanced MS-2 adsorption. The MS-2 breakthrough revealed the existence of reversible and irreversible sorption sites in the sand. Salinity increased MS-2 attachment by compressing the double layers of MS-2 and reversible sorption sites. The salinity also changed some reversible sorption sites into irreversible sorption sites by reversing to positive surface charges of silica powder. An advection-dispersion-sorption model with a two-site reversible-irreversible kinetic sorption was developed to describe MS-2 breakthrough under different salinity conditions. The sorption parameters were estimated and their independence was evaluated by minimizing the total squared error of the MS-2 data. The proposed model showed good agreement with the experimental data for a wide range of salinity levels from fresh water to near seawater. The strong sorption shown in the MS-2 breakthrough at high salinity levels above 8 ppt was able to distinguish the proposed model from other sorption models. This study promotes the understanding of the viral sorption with salinity and provides a useful model for coastal management of viral migration in saline coastal groundwater.     

Characterization of Y2O2S:Eu3+, Mg2+, Ti4+ Long-Lasting Phosphor Synthesized by Flux Method

Long-lasting phosphor Y2O2S∶Eu3 , Mg2 , Ti4 was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased with the increase of Eu2O3 content in Y2O2S∶Eu3 x(0.01≤x≤0.10). On the other hand, the change of unit cell parameter a is not linear dependence. In the Y2O2S∶ Eu3 crystal structure, Eu3 ions only replaced Y3 ions′ places in which it posited center position of c axis. With the increase of Eu2O3 content, the position of the strongest emission peak changed from 540 nm (5D1→7F2 transition) to 626 nm (5D0→7F2 transition), and the maximum intensity was obtained when x=0.09 in Y2O2S∶Eu3 x(0.01≤x≤0.10). This is due to the environment of trivalent europium in the crystal structure of Y2O2S. Doping with Mg2 or Ti4 ions alone cannot get the good long-lasting afterglow effect, whereas co-doping with Mg2 and Ti4 ions and excited with 365 nm ultraviolet light, a strong thermoluminesence peak appeared, red and orange long-lasting phosphorescence (LLP) was also observed and the phosphorescence lasted nearly 3 h in the light perception of the dark-adapted human eye (0.32 mcd*m-2). Thus the LLP mechanism was analyzed.     

Mg~（2＋）,Ca~（2＋）,Ba~（2＋）离子部分取代对SrAl_2O_4：Eu~（2＋）,Dy~（3＋）晶体结构和发光性能的影响

采用高温固相反应法制备了Sr0.9M0.1Al2O4：Eu2＋,Dy3＋（M=Mg,Ca,Ba）长余辉发光材料,并对其晶体结构、光谱性质、余辉特性进行了分析.X射线衍射测试结果表明,Mg2＋,Ca2＋,Ba2＋离子部分取代SrAl2O4基质中的Sr后,基质晶体结构并没有发生改变.光谱测试结果表明,Mg2＋,Ca2＋,Ba2＋取代后发光材料的激发光谱都是一个从250~450 nm范围内的宽激发带,在266nm,320nm,360nm,416 nm处各有一个激发峰.发射光谱中Mg2＋和Ba2＋的取代使波长出现蓝移,而Ca2＋的取代使波长出现红移.余辉测试结果表明,Ca2＋取代后的余辉时间长于Mg2＋和Ba2＋的取代.     

树脂富集铼的研究

用201×7强碱性凝胶型离子交换树脂对钼精矿焙烧烟尘浸出液中的铼进行分离富集工艺条件进行研究。通过对溶液中主要金属离子存在状态的分析,选择用201×7树脂对溶液中铼进行离子交换吸附,对该树脂在实验溶液中的有关吸附交换的表观吸附容量、吸附溶液pH等进行了实验研究,另外选择出了对负载树脂上铼进行有效解吸的解吸剂,并进行了动态解吸。实验结果表明:烟尘浸出液经氧化预处理后,用201×7树脂在常温,pH=9.0时可以对浸出液中的铼有效富集,树脂对铼的表观饱和吸附容量为92 mg/g;采用1 mol/L的硝酸溶液可以对负载树脂上的铼进行有效的解吸。     

BaAl12O19中Mn2+和Tb3+的发光及Tb3+对Mn2+的能量传递

采用溶胶-凝胶法合成了Mn2+、Tb3+单掺及共掺的BaAl12O19荧光粉,对其发光性质和Tb3+对Mn2+的能量传递机理进行了研究.研究结果表明,Tb3+单掺的BaAl12O19荧光粉,发射峰位于440nm、489nm、543nm、587nm和623nm,属于Tb3+的5D3→7FJ和5D4→7FJ (J=6,5,4,3)跃迁发射;Mn2+单掺的荧光粉,发射峰位于516nm,归属于Mn2+的4T1→6A1跃迁发射.Mn2+,Tb3+共掺后,Mn2+的发射强度明显提高,而Tb3+的发光强度降低,Tb3+对Mn2+有能量传递作用.初步证实Tb3+对Mn2+的能量传递机理为激子能量传递.     

Ni2+、Cu2+、Zn2+对氧化亚铁硫杆菌氧化 活性影响

为研究金属离子对氧化亚铁硫杆菌（Acidithiobacillus ferrooxidans,At.f）氧化活性的影响,通过测定经初步驯化的At.f菌在不同初始pH下的生长活性,开展不同浓度梯度的Ni2+、Cu2+、Zn2+及三种金属离子共存时对At.f菌的氧化活性影响的试验。结果表明,当初始pH为1.8时,At.f菌生长活性最好,且低浓度的Ni2+、Zn2+对At.f菌氧化活性影响较小,对两种金属离子的耐受浓度均在20 g/L以上;而该细菌对Cu2+比较敏感,当Cu2+浓度为2.5 g/L时,菌株的生长活性明显下降,特别是10 g/L时,对At.f菌的氧化能力有显著的抑制作用。三种金属离子同时存在时对At.f菌氧化活性的影响大于单一金属离子,当三种金属离子的浓度均为2.5 g/L时,在48小时内对At.f菌的氧化能力有显著的抑制作用,当三种金属离子的浓度均为5 g/L时,80小时时菌株对Fe2+的氧化率极低,说明At.f菌需要经过多种金属离子共存驯化培养后才能更好地运用于多金属复杂矿物的处理。     

4A 沸石对锰渣渗滤液中 Mn2＋吸附-解吸研究

在开展4A 沸石吸附—解吸模拟锰渣渗滤液中 Mn2＋实验的基础上,通过 X 射线衍射分析（XRD）和红外光谱分析（FTIR）研究了4A 沸石吸附 Mn2＋的机制及其解吸行为。结果表明：4A 沸石对模拟锰渣渗滤液中 Mn2＋的去除效率高达99．34％,吸附量最高可达92．84 mg／g,但化学解吸和化学—物理联合解吸对于沸石型离子交换吸附的解吸效果不佳,Mn2＋解吸率均未超过1．6％。XRD 和 FTIR 显示4A 沸石对 Mn2＋的吸附机制主要为离子交换。     

The effects of Mg2+, Mn2+, Zn2+, and Al3+ on the nickel deposit during electrowinning from sulfate bath

The presence of impurities like Mg²⁺, Mn²⁺, Zn²⁺, and Al³⁺ during electrowinning of nickel shows several effects. The effects include current efficiency, deposit quality, purity, crystallographic orientation, surface morphology, and polarization behavior. Addition of the impurities did not change the current efficiency significantly but did change the quality and purity of the electrodeposited nickel. Based on the quality of the deposits obtained, the tolerance limits of these impurities in nickel bath were obtained. Although no deviation of nickel structure from fee was observed, the peak height values for different orientations changed with all of the impurities and the values varied with impurity concentration. The surface morphologies of electrodeposited nickel in the presence of impurities also showed changes. The potentiodynamic scan curves for nickel deposition showed deviations in the presence of all the impurities studied. Based on the results, an attempt was made to correlate the various effects.