Oxidative removal of acetaminophen using zero valent aluminum-acid system: Efficacy, influencing factors, and reaction mechanism

Commercial available zero valent aluminum under air-equilibrated acidic conditions (ZVAl/H⁺/air system) demonstrated an excellent capacity to remove aqueous organic compounds. Acetaminophen (ACTM), the active ingredient of the over-the-counter drug Tylenol^®, is widely present in the aquatic environment and therefore the treatment of ACTM-contaminated water calls for further research. Herein we investigated the oxidative removal of ACTM by ZVAl/H⁺/air system and the reaction mechanism. In acidic solutions (pH < 3.5), ZVAl displayed an excellent capacity to remove ACTM. More than 99% of ACTM was eliminated within 16 hr in pH 1.5 reaction solutions initially containing 2.0 g/L aluminum and 2.0 mg/L ACTM at 25 ± 1\textcelsius. Higher temperature and lower pH facilitated ACTM removal. The addition of different iron species Fe⁰, Fe²⁺ and Fe³⁺ into ZVAl/H⁺/air system dramatically accelerated the reaction likely due to the enhancing transformation of H₂O₂ to HO. via Fenton's reaction. Furthermore, the primary intermediate hydroquinone and the anions formate, acetate and nitrate, were identified and a possible reaction scheme was proposed. This work suggested that ZVAl/H⁺/air system may be potentially employed to treat ACTM-contaminated water.     

春季黄渤海溶解有机碳的平面分布特征

依据2010年4～5月对黄渤海调查所得的数据,分析了黄渤海溶解有机碳(dissolved organic carbon,DOC)的含量及其平面分布特征,并对其影响因素进行了初步探讨.结果表明,2010年春季黄渤海DOC的浓度范围为0.96～4.71 mg.L-1,平均浓度为2.27 mg.L-1.平面分布上,DOC整体呈现南北近岸浓度高、中部外海浓度低的特点.在渤海西部近岸、山东半岛东部及长江口东北部均存在高值,尤其是渤海西部近岸,DOC浓度最高达到4.71 mg.L-1,这主要是受河流输入和沿岸流的影响;低值区则主要集中在南黄海中部外海,DOC浓度普遍低于1.50 mg.L-1.     

Ammonium-dependent regulation of aerobic methane-consuming bacteria in landfill cover soil by leachate irrigation

The impacts of landfill leachate irrigation on methane oxidation activities and methane-consuming bacteria populations were studied by incubation of landfill cover soils with leachate and (NH₄)₂SO₄ solution at different ammonium concentrations. The community structures and abundances of methane-oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) were examined by PCRDGGE and real-time PCR. Compared with the pure (NH₄)₂SO₄ solution, leachate addition was found to have a positive effect on methane oxidation activity. In terms of the irrigation amount, ammonium in leachate was responsible for the actual inhibition of leachate. The extent of inhibitory effect mainly depended on its ammonium concentration. The suppression of the predominant methaneconsuming bacteria, type I MOB, was responsible for the decreased methane oxidation activity by ammonium inhibition. Methaneconsuming bacteria responded diversely in abundance to ammonium. The abundance of type I MOB decreased by fivefold; type II MOB showed stimulation response of fivefold magnification upon the first addition but lessened to be lower than the original level after the second addition; the amount of AOB was stimulated to increase for 20-30 times gradually. Accumulated nitrate from nitrification strengthened the ammonium inhibition on type I and type II MOB, as a result, repetitive irrigation was unfavorable for methane oxidation.     

Fractionation of residual Al in natural water treatment from reservoir with poly-aluminum-silicate-chloride (PASiC): Effect of OH/Al, Si/Al molar ratios and initial pH

An aluminum fractionation study was conducted for a surface reservoir water treatment to understand the performance of poly-aluminum-silicate-chloride (PASiC) in terms of the residual Al fractions as a function of initial pH. The coagulation performance expressed as turbidity and organic matter removal was established as supporting data. Some extra data were evaluated in terms of the residual Al ratio of the composite PASiC coagulant. The main residual Al sources were the Al fractions derived from the use of PASiC. The turbidity and organic matter removal ability was optimal at initial pH 6.00-7.00, while the concentrations of various residual Al species and the residual Al ratio of PASiC were minimal at an initial pH range of 7.00-8.00. Under the conditions of OH/Al molar ratio = 2.00 and Si/Al molar ratio = 0.05, PASiC had superior coagulation performance and comparatively low residual Al concentrations. The Al fraction in the composite PASiC coagulant seldom remained under such conditions. Experimental data also indicated that the suspended (filterable) Al fraction was the dominant species, and organic-bound or organo-Al complex Al was considered to be the major species of dissolved Al in water treated by PASiC coagulation. Additionally, the dissolved inorganic monomeric Al species dominated the dissolved monomeric Al fraction.     

Identification of rice cultivars with low brown rice mixed cadmium and lead contents and their interactions with the micronutrients iron, zinc, nickel and manganese

Paddy fields in mining areas are usually co-contaminated by a cocktail of mixed toxic heavy metals (e.g., Cd and Pb in Pb/Zn mines). However, previous studies on rice cultivars screened for effective metal exclusion have mostly focused on individual metals, and have been conducted under pot-trial or hydroponic solution conditions. This study identified rice cultivars with both low Cd and Pb accumulation under Cd-and Pb-contaminated field conditions, and the interactions of the toxic elements Cd and Pb with the micronutrient elements Fe, Zn, Mn and Ni were also studied. Among 32 rice cultivars tested, there were significant differences in Cd (0.06-0.59 mg/kg) and Pb (0.25-3.15 mg/kg) levels in their brown rice, and similar results were also found for the micronutrient elements. Significant decreases in concentrations of Fe and Mn were detected with increasing Cd concentrations and a significant elevation in Fe, Mn and Ni with increasing Pb concentrations. A similar result was also shown by Cd and Ni. Three cultivars were identified with a combination of low brown rice Cd and Pb, high micronutrient and grain yield (Wufengyou 2168, Tianyou 196 and Guinongzhan). Present results suggest that it is possible to breed rice cultivars with low mixed toxic element (Cd, Pb) and high micronutrient contents along with high grain yields, thus ensuring food safety and quality.     

Persistence and mobility of 2,4-D in unsaturated soil zone under winter wheat crop in sub-tropical region of India

The present study was undertaken to determine the persistence and mobility of 2,4-dichlorophenoxy acetic acid (2,4-D) in unsaturated soil zone under real field conditions for the wheat crop in Roorkee, India. Three experimental plots were chosen in the agricultural field itself to represent the real field conditions in the study area and the potential movement and persistence of herbicide 2,4-D was investigated under three different irrigation treatments. The presence of herbicide along with soil water content was determined in soil at different depths at a temporal scale. The movement of the herbicide was also simulated numerically by solving the coupled soil water content movement and mass transport equations using HYDRUS-1D. The measured soil water content trends and the 2,4-D concentration profiles showed a good agreement with the numerically simulated results. The maximum effect of the herbicide was primarily retained up to 15 cm of the soil profile. The current existing dosage of 0.5 kg ha⁻¹ of pesticide was found to be safe to avoid soil contamination as no residue of 2,4-D was traced at the end of the wheat crop season in any of the plots. Higher concentrations of 2,4-D were also simulated numerically and the simulated results showed that the safe dosage of pesticide application would depend on irrigation treatments.     

兰州市大气中苯并(a)芘与儿童尿中1-羟基芘的分析及风险评价

对兰州市不同区域空气中苯并(a)芘和儿童尿液中1-羟基芘同步采样,分别采用气相色谱-质谱联用法和高效液相色谱法进行检测.结果表明:不同区域苯并(a)芘浓度有显著差别,研究区日均浓度约为对照区日均浓度的两倍.冬季大气中的浓度明显高于夏季,其中研究区冬季均值约为夏季的26.46倍,对照区冬季均值约为夏季的29.41倍.儿童尿中1-羟基芘的浓度与空气中苯并(a)芘的浓度呈一致的变化,冬季研究区儿童尿中1-羟基芘的均值为0.86μmol·(mol肌酐)-1,对照区为0.63μmol·(mol肌酐)-1.冬季研究区儿童的终生超额危险度最高,达到2.32×10-4,接近不可接受水平.     

3-氨丙基三乙氧基硅烷改性蒙脱石的表征及其对Sr(Ⅱ)的吸附研究

3-氨丙基三乙氧基硅烷(APTES)作为偶联剂在粘土功能化方面具有特殊的研究意义.因此,本文采用X射线衍射(XRD)、扫描电镜(SEM)及红外光谱(FTIR)等方法对不同离子交换容量(1.0CEC、1.5CEC、2.0CEC、2.5CEC、3.0CEC、4.0CEC)的APTES改性蒙脱石(APTES-Mt)的结构及表面进行表征与分析,同时对Sr(Ⅱ)的吸附性能进行了研究.结果表明,改性蒙脱石对Sr(Ⅱ)的吸附平衡时间为24h,吸附量随溶液pH(1.0～10.0)的增大而增强,且改性蒙脱石的吸附量是原始蒙脱石吸附量的3倍.改性蒙脱石对Sr(Ⅱ)的吸附作用较强,吸附后的Sr(Ⅱ)不易从材料中解吸出来.XRD、SEM和FTIR等分析结果显示,APTES已经成功插入层间,改性蒙脱石对Sr(Ⅱ)的吸附机理主要为配位吸附.     

利用皂土吸附和介电泳方法间接去除水中的Mn2+

水中重金属去除一直是水处理的技术难点.锰虽然是动物必需的微量元素之一,但是人和动物摄入过量的锰会对神经系统等产生毒害.利用皂土吸附水中的重金属Mn2+,在装有微电极阵列芯片的介电泳池研究装置中,通过调节外加交流电压,捕获悬浮液中的皂土从而间接去除Mn2+.吸附了微量重金属离子的皂土被捕获到电场强度较大的区域,发生了正介电泳.该研究为建立一种从废水中间接去除重金属离子的实际可行方法奠定了实验基础,不存在二次污染.     

Adsorption characteristics and mechanism of Cr （Ⅵ） on chitoan-yttrium porous microsphere

以壳聚糖和Y2（OH）5NO3为原料通过乳液交联法制备了壳聚糖-钇（Ch—Y）复合微球,通过扫描电镜、透射电镜、X射线衍射、红外光谱等方法对其表面形貌、结构进行了表征.探讨了溶液的pH值、反应时间、投加量、离子初始浓度对其吸附性能的影响.研究结果表明,壳聚糖-钇（Ch—Y）复合微球在pH值为3的酸性环境中对Cr（Ⅵ）保持了较高的吸附能力,吸附容量为52.39mg·g-1,其吸附行为符合Langmuir吸附等温模型;通过吸附机理的研究,发现壳聚糖-钇（Ch—Y）对Cr（Ⅵ）吸附是化学吸附静电吸附协同氧化Cr（Ⅵ）离子作用来实现的.