Electrochemical Properties of Electrodes with Different Shapes and Diffusion Kinetic Analysis of Microbial Fuel Cells on Ocean Floor     

FU Yubin  LIU Jia  SU Jia  ZHAO Zhongkai  LIU Yang  XU Qian 《青岛海洋大学学报(英文版)》2012,(1):25-31

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负载型纳米Pd/Fe对挥发性氯代烃的去除     

尚海涛  李智灵  杨琦  席宏波  郝春博 《现代地质》2008,22(2):313-320

氯代烃的污染治理已成为当今世界最热门的研究领域之一。以水体中最常见的氯代烃污染物1,1-二氯乙烯（1,1-DCE）、林丹（γ-HCH）为主要目标污染物,探讨了不同条件下负载型纳米Pd/Fe对氯代烃的去除效果。负载型纳米Pd/Fe采用浸渍→液相还原→还原沉淀的方法制备,透射电镜显示采用该方法制备的负载型金属钯和铁的平均粒径均在纳米级范围内。负载型纳米Pd/Fe具有较高的表面反应活性,当负载型纳米Pd/Fe 用量为40 g/L、反应时间达2 h时,1.1-二氯乙烯和林丹的去除率分别达到85%和100%。脱氯率与Pd/Fe投加量、钯含量、初始pH值、反应温度等因素有关,与溶液的初始浓度关系不大。负载型纳米Pd/Fe对11-DCE和γ-HCH去除均符合一级反应动力学方程,速率常数分别为0-528 3 h^-1及2-012 9 h^-1,反应的半衰期t1/2分别为1.31 h和0.34 h。推断在反应过程中,Fe腐蚀产生的H2为主要还原剂,Pd是良好的加氢催化剂,在金属颗粒表面形成高浓度反应相,使反应短时间内完成。  相似文献   

Phosphorus retention and release by sediments in the eutrophic Mai Po Marshes, Hong Kong   总被引：5，自引：0，他引：5  

Lai DY  Lam KC 《Marine pollution bulletin》2008,57(6-12):349-356

This study examined the phosphorus retention and release characteristics of sediments in the eutrophic Mai Po Marshes in Hong Kong. Results of chemical fractionation show that the sum of inorganic P pools exceeded 50% of the total sediment P content, with the redox-sensitive iron-bound P (Fe(OOH) approximately P) being the dominant P fraction. Given the considerable average Fe(OOH) approximately P concentration of 912 microg g(-1), Mai Po sediments demonstrated a great potential to release bioavailable P under low sediment redox potentials. This was further supported by the high mean anaerobic P flux of 31.8 mg m(-2)d(-1) recorded in Mai Po sediment cores, indicating the role of bottom sediments as a net P source. Although sediments in Mai Po had appreciable Langmuir adsorption maxima (1642-3582 mg kg(-1)), the high zero equilibrium P concentrations (0.02-0.51 mg L(-1)) obtained suggest that sediment sorption processes would contribute to sustaining the eutrophic conditions in overlying water column even with a further reduction in external P load. Concerted efforts should be made to reduce internal loading of P, especially under reducing conditions, to complement the implementation of zero discharge policy for Deep Bay for effective eutrophication abatement and long-term water quality improvement in the Mai Po Marshes.  相似文献   

Biosorption of Methylene Blue from Aqueous Solution Using a Bioenergy Forest Waste: Xanthoceras sorbifolia Seed Coat     

Zengyu Yao  Lihua Wang  Jianhua Qi 《洁净——土壤、空气、水》2009,37(8):642-648

Xanthoceras sorbifolia seed coat (XSSC), a bioenergy forest waste, was used for the adsorption of methylene blue (MB) from aqueous solutions. The effects of adsorbent dosage, pH, adsorbate concentration and contact time on MB biosorption were studied. The equilibrium adsorption data was analyzed by Langmuir and Freundlich isotherm models. The results indicated that the Langmuir model provided the best correlation with the experimental data. The adsorption capacity of XSSC for MB was determined with the Langmuir model and was found to be 178.6 mg/g at 298 K. The adsorption kinetic data was modeled using the pseudo‐first order, pseudo‐second order, and intraparticle diffusion kinetic equations. It was seen that the pseudo‐second order equation could describe the adsorption kinetics, and intraparticle diffusion was not the sole rate controlling factor. Thermodynamic parameters were also evaluated. Standard Gibbs free energy was spontaneous for all interactions, and the biosorption process exhibited exothermic standard enthalpy values. The results indicated that XSSC is an attractive alternative for removing cationic dyes from wastewater.  相似文献   

辽河西部凹陷古近系烃源岩生烃动力学特征   总被引：4，自引：0，他引：4  

刘立峰  姜振学  钟宁宁  郑菲菲 《地球科学》2009,34(5):799-805

针对辽河西部凹陷不同岩性、不同干酪根类型18块样品进行了较详细的开放体系生烃动力学研究, 模拟结果反映出相同岩性不同有机质类型烃源岩动力学特征存在较大的差异, 有机质类型越好, 平均活化能越小, 主频活化能对应的反应分数越大, 活化能分布范围越窄, 表明有机质类型对烃源岩生烃动力起着决定性作用.应用平行一级反应模型, 结合埋藏史、热史对辽河西部凹陷古近系烃源岩生烃史进行了定量研究, 层位上, 西部凹陷沙三、沙四段是主力烃源岩, 分别占总生烃量的63.9%和18.5%, 其次为沙一二段和东营组, 4套烃源岩累计生烃量为328.09×108t;东营期是主要的生烃时期.   相似文献   

Removal of EDTA from Aqueous Solutions Using Activated Carbon Prepared from Rubber Wood Sawdust: Kinetic and Equilibrium Modeling     

K. Anoop Krishnan  K. G. Sreejalekshmi  Sumol Varghese  T. S. Anirudhan 《洁净——土壤、空气、水》2010,38(4):361-369

Adsorptive removal of EDTA (ethylenediaminetetraacetic acid) from aqueous solution was studied using steam pyrolyzed activated carbon. Rubber wood sawdust, obtained from a local timber facility at Kodangavila, Trivandrum, Kerala, India was used as the precursor for the production of the activated carbon. Batch adsorption experiments were employed to monitor and optimize the removal process. The experimental parameters, i. e., solution pH, agitation time, initial EDTA concentration and adsorbent dosage, affecting the adsorption of EDTA onto sawdust activated carbon (SDAC) were optimized. The inner core mechanism for the interaction between EDTA and SDAC, which resulted in the adsorption process, was also discussed. The change in amount of EDTA adsorbed onto SDAC and CAC (commercial activated carbon) was compared over a wide range of pH (2.0–8.0). The maximum removal of EDTA took place in the pH range of 4.0–6.0 for SDAC and 5.0–5.5 for CAC, which demonstrates the effectiveness of the former adsorbent. Kinetic as well as equilibrium studies were performed to determine the rate constant and adsorption capacity, respectively. The adsorption kinetic data was fitted with pseudo‐first‐order kinetics and the equilibrium data was shown to follow the Langmuir isotherm model. These observations explain the formation of a monolayer of EDTA on the surface of SDAC as confirmed by the slow approach to equilibrium after 4 h of contact time. The adsorption capacity of SDAC for the removal of EDTA was 0.526 mmol/g and is seen to be greater than that of CAC and other reported adsorbents (0.193–0.439 mmol/g). Finally, it is clear that the production of steam pyrolyzed activated carbon in the presence of K₂CO₃ greatly enhanced EDTA removal and resulted in a product with possible commercial value for wastewater treatment strategies.  相似文献   

Isotherm Study of Phosphorus Uptake from Aqueous Solution Using Aluminum Oxide     

Liang Zhang  Song Hong  Jing He  Fuxing Gan  Yuh‐Shan Ho 《洁净——土壤、空气、水》2010,38(9):831-836

Aluminum oxide, which could be an alternative filter media for phosphorus uptake from aqueous solution, was selected as an adsorbent for the isotherm study of phosphorus uptake from aqueous solution. Batch method was adopted to investigate the adsorption behavior of phosphorus onto aluminum oxide. The Langmuir, Freundlich, and Redlich–Peterson isotherms were used to analyze the experimental data by both the linear and nonlinear regression methods. The adsorption experiment was conducted at various temperatures, to choose the appropriate method and obtain the creditable adsorption parameters for phosphorus uptake studies. The results indicated that the nonlinear regression method might be a better way to compare the best‐fitting isotherm and obtain the parameters for the adsorption of phosphorus onto aluminum oxide. Both the Redlich–Peterson and the Freundlich isotherms have high coefficients of determination for the adsorption of phosphorus onto aluminum oxide at various temperatures. In addition, a new relationship between the Redlich–Peterson and the Freundlich isotherm parameters was presented.  相似文献   

Removal of Organic Pollutants from Wastewater Using Wood Fly Ash as a Low‐Cost Sorbent     

Sawanya Laohaprapanon  Marcia Marques  William Hogland 《洁净——土壤、空气、水》2010,38(11):1055-1061

In this study, untreated and treated wood fly ash (WA) was used as a low‐cost sorbent in batch sorption tests to investigate the removal of organic pollutants from a real wastewater generated by cleaning/washing of machinery in a wood‐laminate floor industry in Sweden. The experiments focused on the effect of the WA dosage and particle size on the removal efficiency for organic compounds. With a WA dosage of 160 g L^?1 and a particle size less than 1 mm, the reductions of chemical oxygen demand (COD), biologic oxygen demand, and total organic carbon were 37 ± 0.4, 24 ± 0.4, and 30 ± 0.3%, respectively. Pre‐treatment of WA with hot water improved the COD removal efficiency by absorption from 37 ± 0.4 to 42 ± 1.6% when the same dosage (160 g L^?1) was applied. Sorption isotherm and sorption kinetics for COD using untreated WA can be explained by Freundlich isotherm and pseudo‐second‐order kinetic models. Intra‐particle diffusion model indicates that pore diffusion is not the rate‐limiting step for COD removal. Based on the experimental data, WA could be used as an alternative low‐cost sorption media/filter for removal of organic compounds from real industrial wastewater.  相似文献   

Malachite Green Adsorption onto Chitosan Coated Bentonite Beads: Isotherms,Kinetics and Mechanism     

Wan Saime Wan Ngah  Noorul Farhana Md Ariff  Azhan Hashim  Megat Ahmad Kamal Megat Hanafiah 《洁净——土壤、空气、水》2010,38(4):394-400

The removal of Malachite green (MG) from aqueous solutions by cross‐linked chitosan coated bentonite (CCB) beads was investigated and the CCB beads were characterized by Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X‐ray diffraction (XRD) analysis. Solubility and swelling tests were performed in order to determine the stability of the CCB beads in acidic solution, basic solution and distilled water. The amount of MG adsorbed was shown to be influenced by the initial pH of the solution, contact time and the initial MG concentration. A kinetic study indicated that a pseudo‐second‐order model agreed well with the experimental data. From the Langmuir isotherm model, the maximum adsorption capacity of MG was found to be 435.0 mg g^–1. Desorption tests were carried out at different concentrations of EDTA, H₂SO₄ and NaOH. However, all desorbing solutions showed zero recovery of MG at all concentrations.  相似文献   

Dynamic Treatment Response of Olive Mills Wastewater Using Series of Adsorption Steps     

Mohammed‐Osama J. Azzam  Kamal Al‐Malah  Ziad Al‐Gazzawi  Saad A. Al‐Omari 《洁净——土壤、空气、水》2010,38(9):822-830

Olive mills wastewater (OMW) is a critical environmental problem in the Mediterranean area due to its extremely high levels of COD and phenols. In this study, a group of adsorption experiments were conducted to investigate the dynamic response of the pH, COD, phenols, TSS, TDS, and TS concentrations of pretreated OMW, using different concentrations of activated carbon as adsorbent. The pretreatment included sedimentation and filtration of OMW. The pretreated OMW was then subjected to adsorption. A series of adsorption steps in stirred batch vessels were studied, namely, one stage, two‐stage countercurrent, and three‐stage countercurrent adsorption systems. A combined two‐ two‐stage countercurrent adsorption steps were also studied. Experimental results showed that such treatment protocols were promising. For example, a treatment protocol composed of a three‐stage countercurrent adsorption process using activated carbon of concentration of 24 g/L of OMW was able to reduce the COD from 60 000 mg/L down to 22 300 mg/L, while phenols were reduced from 450 to 15 mg/L.  相似文献