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 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 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 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 Competitive Adsorption of Iron and Natural Organic Matter in Groundwater Using Granular Activated Carbon written by Omar Al-Attas and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The treatment of potable water in Vars, ON is accomplished by filtering the colored, iron-laden groundwater through granular activated carbon (GAC) filters. When first installed, these filters unexpectedly experienced chromatographic displacements of iron into the produced water which resulted in orange-brown water at consumers' taps. The treatment plant was later modified by adding potassium permanganate oxidation and a greensand filter prior to the GAC adsorption columns. Consequently, iron was almost completely removed and no longer caused operational problems. The main objective of this dissertation is to study the interactions between natural organic matter (NOM) and iron that caused the observed chromatographic effect. This study was divided into three main stages: a) characterization study on Vars groundwater and its treatment system; b) study of the competitive adsorption of iron with NOM in Vars groundwater; and c) evaluation of the rapid small-scale column test (RSSCT) for predicting the full-scale GAC column breakthroughs. The characterization of Vars groundwater showed that ferrous iron was found to be the dominant iron species, representing 90% of the total iron, and that 15 - 35% of the iron was complexed with NOM. It was hypothesized that the chromatographic displacement of iron from the GAC columns was caused by NOM-iron complexes; however, field mini-column experiments showed this was not the case. Thus, competitive adsorption between iron and NOM was seen as the more likely cause of the chromatographic effect. The adsorption capacity of ferrous iron in Vars raw water was less than that in organic-free water by a factor of 7 due to the competition with NOM over the GAC adsorbing sites. However, the NOM adsorption capacity was not reduced due to the presence of ferrous iron. It was hypothesized that ideal adsorption solution theory (IAST) models, which have been successful in describing competitive adsorption between target organic compounds and NOM, could model the competition between an inorganic compound such as ferrous iron and NOM. The hypothesis was proved to be correct, and the adsorption isotherm of iron in competition with NOM in Vars groundwater was simulated very well by several versions of the IAST model. However, none of the models were capable of simulating the competitive adsorption of NOM and ferrous iron simultaneously. Since the presence of iron did not significantly reduce the adsorption capacity of NOM, a simplified approach of using the single-solute NOM isotherm to represent the competitive NOM isotherm was recommended. The performance of the rapid small-scale column test (RSSCT) was evaluated in order to simulate the iron chromatographic effect observed at Vars' full-scale GAC column. The RSSCT was not capable of predicting the iron phenomenon and the test proved to be problematic due to the oxidation and precipitation of iron within the small voids between the small-scale column's GAC particles. The RSSCT, using constant and linear diffusivities, were applied to simulate the NOM adsorption after greensand treatment. Integrating both diffusivities, the tests predicted the onset and slope of the NOM breakthrough up to 10-L water treated/g GAC, which is equivalent to 250 days of operation time for the full-scale column. However, the NOM breakthroughs deviated beyond that point and the RSSCT using constant diffusivity underestimated the column performance greatly. On the other hand, the linear diffusivity RSSCT underestimated the performance to a lesser degree and its NOM breakthrough was quite parallel to the full-scale performance with lower NOM removals of 15%. The higher long-term NOM removal in the full-scale system may be explained by biodegradation, a phenomenon that was not considered by the short duration of RSSCT.

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 Activated Carbon Adsorption of Trace Organic Compounds written by Vernon L. Snoeyink and published by . This book was released on 1977 with total page 116 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 Competitive Adsorption on Activated Carbon from Bi solute Systems of Selected Organic Contaminants Found in Drinking Waters in Low Concentrations written by Carl W. Baxter and published by . This book was released on 1979 with total page 192 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 Partition and Adsorption of Organic Contaminants in Environmental Systems written by Cary T. Chiou and published by John Wiley & Sons. This book was released on 2003-07-07 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given the presence of a wide variety of contaminants in the environment, it is important to understand what drives a contaminant from one medium to another, as well as the manner and extent to which a contaminant associates with the different media or phases within a local environmental system. Partition and Adsorption of Organic Contaminants in Environmental Systems forms a comprehensive resource on the behavioral characteristics of contaminants so that appropriate strategies can be adopted to either prevent or minimize their adverse impacts on human welfare and natural resources. Cary Chiou’s far-reaching text depicts the processes by which nonionic organic contaminants are sorbed to natural biotic and abiotic substances. This book focuses on physical principles and system parameters that affect the contaminant uptake by soil from water, air, and other media; by fish from water; and by plants from soil and water. As contaminant uptake by natural organic substances is often predominantly a partition interaction, the partition characteristics in several solvent-water model mixtures are treated in detail to elucidate the relevant physicochemical parameters. The account of contaminant sorption to soils, fish, and plants is strengthened by companion chapters on: Fundamentals of solution theory Interphase partition equations Fundamentals of adsorption theory Vapor adsorption on mineral and carbonaceous solids No other single source in the field delivers as compelling a combination of background understanding and "state-of-the-science" comprehension of current issues. Ideally suited for a graduate-level environmental course, Partition and Adsorption of Organic Contaminants in Environmental Systems also serves as a technical guide to current and future research in the field.

Download or read book Effect of Pore Size Distribution on Competitive Adsorption of Trace Organic Micropollutants on Activated Carbon in Natural Water written by Costas Pelekani and published by . This book was released on 1997 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Organic Matter Occurrence in Arizona and Innovative Treatment by Granular Activated Carbon written by Chao-An Chiu and published by . This book was released on 2012 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Population growth and fresh water depletion challenge drinking water utilities. Surface water quality is impacted significantly by climate variability, human activities, and extreme events like natural disasters. Dissolved organic carbon (DOC) is an important water quality index and the precursor of disinfection by-products (DBPs) that varies with both hydrologic and anthropogenic factors. Granular activated carbon (GAC) is a best available technology for utilities to meet Stage 2 D/DBP rule compliance and to remove contaminants of emerging concern (CECs) (e.g., pharmaceutical, personal care products (PCPs), etc.). Utilities can operate GAC with more efficient and flexible strategies with the understanding of organic occurrence in source water and a model capable predicting DOC occurrence. In this dissertation, it was found that DOC loading significantly correlated with spring runoff and was intensified by dry-duration antecedent to first flush. Dynamic modeling based on reservoir management (e.g., pump-back operation) was established to simulate the DOC transport in the reservoir system. Additionally, summer water recreational activities were found to raise the level of PCPs, especially skin-applied products, in raw waters. GAC was examined in this dissertation for both carbonaceous and emerging nitrogenous DBP (N-DBP) precursors (i.e., dissolved organic nitrogen (DON)) removal. Based on the experimental findings, GAC preferentially removes UV254-absorbing material, and DOC is preferentially removed over DON which may be composed primarily of hydrophilic organic and results in the low affinity for adsorption by GAC. The presence of organic nitrogen can elevate the toxicity of DBPs by forming N-DBPs, and this could be a major drawback for facilities considering installation of a GAC adsorber owing to the poor removal efficiency of DON by GAC. A modeling approach was established for predicting DOC and DON breakthrough during GAC operation. However, installation of GAC adsorber is a burden for utilities with respect to operational and maintenance cost. It is common for utilities to regenerate saturated GAC in order to save the cost of purchasing fresh GAC. The traditional thermal regeneration technology for saturated GAC is an energy intensive process requiring high temperature of incineration. Additionally, small water treatment sites usually ship saturated GAC to specialized facilities for regeneration increasing the already significant carbon footprint of thermal regeneration. An innovative GAC regeneration technique was investigated in this dissertation for the feasibility as on-site water treatment process. Virgin GAC was first saturated by organic contaminant then regenerated in-situ by iron oxide nanocatalysts mixed with hydrogen peroxide. At least 70 % of adsorption capacity of GAC can be regenerated repeatedly for experiments using modeling compound (phenol) or natural organic matter (Suwannee River humic acid). The regeneration efficiency increases with increasing adsorbate concentration. Used-iron nanocatalysts can be recovered repeatedly without significant loss of catalytic ability. This in-situ regeneration technique provides cost and energy efficient solution for water utilities considering GAC installation. Overall, patterns were found for DOC and CEC variations in drinking water sources. Increasing concentrations of bulk (DOC and DON) and/or trace organics challenge GAC operation in utilities that have limited numbers of bed-volume treated before regeneration is required. In-situ regeneration using iron nanocatalysts and hydrogen peroxide provides utilities an alternative energy-efficient operation mode when considering installation of GAC adsorber.

Download or read book Activated Carbon Adsorption written by Roop Chand Bansal and published by CRC Press. This book was released on 2005-05-24 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: High surface area, a microporous structure, and a high degree of surface reactivity make activated carbons versatile adsorbents, particularly effective in the adsorption of organic and inorganic pollutants from aqueous solutions. Activated Carbon Adsorption introduces the parameters and mechanisms involved in the activated carbon adsorption

Download or read book Interferences in Trace Contaminant Removal by Adsorption from Water for Groundwater Recharge written by Kevin Gerard McBride and published by . This book was released on 1977 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Activated Carbon for Water and Wastewater Treatment written by Ferhan Cecen and published by John Wiley & Sons. This book was released on 2011-09-19 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph provides comprehensive coverage of technologies which integrate adsorption and biological processes in water and wastewater treatment. The authors provide both an introduction to the topic as well as a detailed discussion of theoretical and practical considerations. After a review of the basics involved in the chemistry, biology and technology of integrated adsorption and biological removal, they discuss the setup of pilot- and full-scale treatment facilities, covering powdered as well as granular activated carbon. They elucidate the factors that influence the successful operation of integrated systems. Their discussion on integrated systems expands from the effects of environmental to the removal of various pollutants, to regeneration of activated carbon, and to the analysis of such systems in mathematical terms. The authors conclude with a look at future needs for research and develoment. A truly valuable resource for environmental engineers, environmental and water chemists, as well as professionals working in water and wastewater treatment.

Download or read book The Sorption of Nonionic Organic Contaminants to Natural Dissolved Organic Matter and Its Implication for Facilitated Contaminant Transport written by Bruce Eric Herbert and published by . This book was released on 1992 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: