Download or read book Desorption of Trace Contaminants From Activated Carbon Effect of Strongly Competing and Pore Blocking Background Organic Matter on Desorption Kinetics written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms of Competitive Adsorption Between Trace Organic Contaminants and Natural Organic Matter on Activated Carbon written by Li Ding and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Activated carbon adsorption is widely used in water treatment for removal of various organic micropollutants; nonetheless, the presence of natural organic matter (NOM) in source water can reduce its efficiency for micropollutant removal. NOM has been shown to compete with target contaminant via different mechanisms: direct competition for available adsorption sites which reduces equilibrium capacity for target compounds, blocking of pore entrance which reduces diffusion rate of the target compounds, and covering of surface sites which may actually enhances diffusion rate of the target compounds. The objective of this dissertation study was to further elucidate the individual competitive effects, to investigate how pore sizes of adsorbents and molecular structure of competing compounds affect competition and to gain a comprehensive understanding of the competitive adsorption. Atrazine, a widely used herbicide in the United States, was used as the trace-level target contaminant and NOM from different source waters as well as NOM surrogates were used as the competing compounds. Powdered activated carbons (PACs) with different pore size distribution (PSD) were used. The PSD was found to have great influence on the pore blockage (PB) effect caused by NOM. The equilibrium capacity of the NOM used in this study was best correlated to the amount of pores of diameter 15-50 ©5, which was also inversely related to the magnitude of the pore blockage effect. Activated carbon that has more surface area in this pore size range had a smaller PB effect on atrazine adsorption kinetics at the same NOM loading. This finding indicated that mesopores are important in realizing adsorption capacity for trace compounds by alleviating the adverse PB effect. The site covering effect was confirmed with additional types of PACs and various competing compounds. More important, the correlation equation that describes the enhanced surface diffusion coefficient for atrazine as a function of the loading of the site-covering compounds was found to be independent of either the PAC type or the competing compound type. The key component was to quantify the competing compound as the equivalent background compound (EBC), which reflected the extent of active sites being covered. iii The site competing effect, the site covering effect and the pore blocking effect were evaluated for five NOM surrogates with different sizes. The smaller molecules were generally more effective in reducing the equilibrium capacity of the target compound. However, for molecules of similar molecular weight, elongated molecules tended to have more equilibrium effect than round molecules. From a kinetic perspective, the enhancement in diffusivity was within one order of magnitude for all five surrogates, while the extent of the PB effect was greatly relying on molecular size that large-sized surrogates caused a much stronger PB effect. Therefore, the overall kinetic effect was dependent on molecular size and the PB effect was usually dominant except for very small molecules. Consistent with the enhanced kinetics associated with pre-adsorbed site-covering competing compounds, atrazine preloading was found to also increase the diffusion coefficient of atrazine, and the extent of enhancement caused by atrazine was greater than that caused by competing compounds. Several explanations were proposed for the difference, which include the micropore filling hypothesis and the artifact associated with the EBC method that was used for site-covering loading quantification.

Download or read book Effects of Activated Carbon Characteristics on Organic Contaminant Removal written by Detlef R. U. Knappe and published by IWA Publishing. This book was released on 2004-01-01 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many water treatment plants need to remove objectionable trace organic compounds, and activated carbon adsorption is often the best available technology. Utilities face the challenge of having to choose from a large variety of activated carbons, and iodine number or BET surface area values are often utilized in the selection process. Although neither parameter correlates well with adsorption capacities, alternative activated carbon selection criteria based on fundamental adsorbent and adsorbate properties are lacking to date. The first objective of this research was to systematically evaluate the effects of activated carbon pore structure and surface chemistry on the adsorption of two common drinking water contaminants: the relatively polar fuel oxygenate methyl tertiary-butyl ether (MTBE) and the relatively nonpolar solvent trichloroethene (TCE). The second objective was to develop simple descriptors of activated carbon characteristics that facilitate the selection of suitable adsorbents for the removal of organic contaminants from drinking water.Originally published by AwwaRF for its subscribers in 2003 This publication can also be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below

Download or read book Activated Carbon Adsorption of Trace Organic Compounds written by Vernon L. Snoeyink and published by . This book was released on 1977 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Kinetics of Trace Metals Sorption on and Desorption from Soils written by Zhenqing Shi and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the kinetics of trace metals sorption and desorption on soils is important for better prediction of metal behavior in the environment. In this dissertation, the effect of solution chemistry and soil composition on trace metal sorption and desorption kinetics was investigated. Based on the experimental results, predictive kinetics models were formulated and successfully used to describe the kinetics of trace metals sorption and desorption on a variety of soils. The kinetics experiments were conducted with a stirred-flow method. A number of soil samples, which cover a wide range of soil properties from USA and European countries, were selected to test the effect of soil composition. The effects of solution chemistry, pH, metal loadings, and dissolved organic matter (DOM) concentration, were also systematically examined. Most of kinetics experiments were run with two trace metals, copper and zinc, which demonstrated very different kinetics behaviors. The solution pH has significant effect on the Cu and Zn sorption and desorption kinetics which can be accounted by the proton competition. DOM greatly enhanced Cu release but had little effect on Zn, attributed to formation of strong Cu-DOM complex decreasing the Cu ion re-adsorption on soils. Among all soil components, soil organic matter (SOM) is the dominant phase controlling Cu and Zn sorption and desorption kinetics. The effect of residence time was also tested. The kinetics models were formulated and successfully used to describe the Cu and Zn sorption and desorption kinetics under different solution chemistry and soil compositions. The models are based on the mass balance of the flow system and incorporate the chemical reactions between metals and soils. For Zn, a two-site kinetics model, including one fast and one slow site, was necessary. The soil organic carbon (SOC) is the major model parameter accounting for the effect of soil properties on Zn sorption and desorption kinetics. The organic carbon normalized sorption rate coefficients can be applied to different soils based on their SOC concentrations. One set of rate coefficients can be applied to different influent Zn concentrations, which corresponds to the linear portion of the Zn sorption isotherm. The sorption rate coefficients were dependent on solution pH which was accounted for by Zn and proton competition. The same model parameters can be applied to different flow rates. (Abstract shortened by UMI.).

Download or read book Desorption of Organic Micropollutants from Activated Carbon Impact of Dissolved Organic Matter and Adsorbent Characteristics written by Geert Aschermann and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Activated Carbon Adsorption of Organic Matter written by Seongho Hong and published by . This book was released on 1995 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Activated Carbon Surface Chemistry and Pore Structure on the Adsorption of Trace Organic Contaminants from Aqueous Solution written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The principal objectives of this research were (1) to identify activated pore structure and surface chemistry characteristics that assure the effective removal of trace organic contaminants from aqueous solution, and (2) to develop a procedure to predict the adsorption capacity of activated carbons from fundamental adsorbent and adsorbate properties. To systematically evaluate pore structure and surface chemistry effects on the adsorption of organic micropollutants from aqueous solution, a matrix of activated carbon fibers (ACFs) with three activation levels and four surface chemistry levels was prepared and characterized. In addition, three commercially available granular activated carbons (GACs) were studied to verify whether correlations developed for the ACF matrix are valid for adsorbents that are typically used for water treatment. BET surface area, pore size distribution, elemental composition, point of zero charge and infrared spectroscopy data were obtained to characterize the adsorbents. The results showed that the ACF matrix prepared in this study permits a fairly independent evaluation of surface chemistry and pore structure effects on organic contaminant adsorption from aqueous solution. Methyl tertiary-butyl ether (MTBE), a relatively hydrophilic adsorbate, and trichloroethene (TCE), a relatively hydrophobic adsorbate, served as adsorbate probes. To evaluate the effects of natural organic matter (NOM) on MTBE and TCE adsorption capacities, isotherm experiments were conducted in ultrapure water and Sacramento-San Joaquin Delta water. With respect to surface chemistry, both single-solute isotherms and isotherms in the presence of NOM indicated that hydrophobic adsorbents more effectively removed TCE and MTBE from aqueous solution than hydrophilic adsorbents. Enhanced water adsorption on polar surface sites explained the poorer performance of the hydrophilic adsorbents. Based on the elemental composition of the low-ash carbons evaluated in this study, act.

Download or read book Effect of Surface Groups on Adsorption of Pollutants written by Robert W. Coughlin and published by . This book was released on 1970 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adsorption and Desorption Characteristics of Natural Organic Matter in Natural Waters on Granular Activated Carbon written by Megan Denise Storrar and published by . This book was released on 2006 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Trace Contaminant Adsorption and Sorbent Regeneration written by Lockheed Missiles and Space Company and published by . This book was released on 1970 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Activated Carbon Surface Chemistry and Pore Structure on the Adsorption of Trace Organic Contaminants from Aqueous Solution written by Lei Li and published by . This book was released on 2002 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: trace organic contaminants, pore structure, surface chemistry, adsorbent.

Download or read book Sorption Equilibrium and Desorption Kinetics of Hydrophobic Pollutants in Porous Media written by Karen Elizabeth Gardner and published by . This book was released on 1994 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adsorption Technology in Water Treatment written by Eckhard Worch and published by Walter de Gruyter. This book was released on 2012-08-31 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adsorption processes have played a central role in water treatment for many years but their importance is on the rise with the continuous discoveries of new micropollutants in the water cycle (pharmaceuticals for example). In addition to the classical application in drinking water treatment, other application fields are attracting increasing interest, such as wastewater treatment, groundwater remediation, treatment of landfill leachate, and so on. Based on the author's long-term experience in adsorption research, the scientific monograph treats the theoretical fundamentals of adsorption technology for water treatment from a practical perspective. It presents all the basics needed for experimental adsorption studies as well as for process modelling and adsorber design. Topics discussed in the monograph include: introduction into basic concepts and practical applications of adsorption processes; adsorbents and their characterisation, single and multi-solute adsorption equilibria, adsorption kinetics, adsorption dynamics in fixed-bed adsorbers and fixed-bed adsorber design, regeneration and reactivation of adsorbents, introduction into geosorption processes in bank filtration and groundwater recharge. According to the increasing importance of micropollutants in the water cycle, particular attention is paid to their competitive adsorption in presence of background organic matter. Clear illustrations, extensive literature references and a useful index make this work indispensible for both scientists and technicians involved in water treatment.

Download or read book Behavior of Metals in Soils written by Joan E. McLean and published by . This book was released on 1992 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adsorption of Organic and Emerging Pollutants on Carbon Materials in Aqueous Media Environmental Implications written by Jordi Lladó Valero and published by . This book was released on 2016 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last two decades an increasing presence of organic substances such drugs, pesticides, etc. has been detected in water which may affect the health of the organisms and the environment. Some of these contaminants remain in the water after the usual treatment in sewage plants. This fact makes evident the need of introduction of the tertiary treatments that allow the complete elimination of these substances. This Doctoral Thesis researches for the elimination of different organic and emerging compounds present in water by means of the adsorption with new activated carbons. In particular, new carbon materials from different wastes, coal, synthetic materials, which have been produced and characterized, allow the adsorption of the organic compounds widely used in society. Different characteristics of the adsorbents (chemical composition, functional groups, texture, etc.) and of adsorbates (dimensions, hydrophobicity, pKa, functional groups, etc.) that influence on the adsorption process have been studied. Moreover, in this work, an analysis and kinetic model have been proposed. The analytic model allow, by chemometrics, enhancing the quantification of two or more organic compounds in solution by spectroscopy UV-vis. The kinetic model proposed provides a better comprehension and interpretation, as a better prediction of the different parameters on the adsorption process. In this sense, the following Thesis presents five works which have allowed a better comprehension of the adsorption process by means carbon materials from different origin. The first work, "highly microporous activated carbons from biocollagenic wastes as adsorbents or aromatic pollutants in water originating from industrial activities", about the texture and chemical composition of activated carbon from biocollagenic wastes which have been studied in order to observe how these parameters affect on the adsorption of aromatic monosubstitued compounds. Moreover, different variables as temperature and activating agent are studied in the process of manufacture activated carbons. The second work, "Removal of pharmaceutical and Iodinated Contrast Media (ICM) compounds on carbon xerogels and activated carbons. NOM and textural properties influences", shows the important role of pore size distribution in activated carbon which plays on the adsorption of different pharmaceuticals (salicylic acid, paracetamol, diclifenac, etc.) and iodinated contrast media (iohexol, iodixanol, iomeprol, etc) of different size. The influence of natural organic matter (NOM) in water is also studied in the adsorption of the all pollutants. The adsorption of paracetamol, phenol and salicylicacid in different coal-based activated carbon is showed in the contain of the work "Removal of pharmaceutical pollutants in water using coal-based activated carbons". In this work, the chemical characteristics on the surface of activated carbons are studied in order to observe the influence in the adsorption of different organic compounds; and also the influence of the pH water. The results showed an increase of adsorption of salicylates due to the presence of sulphur on the surface of the adsorbent. The fourth work; "Multicomponent adsorption on coal-based activated carbons on aqueous media: new cross-correlation analysis method", as a continuation of the previous work, shows a new chemometric technique that allows to analysis the binary and ternary solutions correctly by UV-vis spectroscopy. Moreover, the competitive effect between two or three molecules is studied on the adsorption process. In the last work, "Role of activated carbon properties in atrazine and paracetamol adsorption equilibrium and kinetics", a new kinetic model is proposed for the adsorption of paracetamol and atrazine using activated carbon from sewage sludge and two, commercial, activated carbons.

Download or read book Analysis and Modeling of the Impacts of Background Organic Matter on TCE Adsorption by Activated Carbon written by Margaret Caroline Carter and published by . This book was released on 1993 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissertation (Ph.D)--University of Michigan.