Effects of Activated Carbon Characteristics on Organic Contaminant Removal

Effects of Activated Carbon Characteristics on Organic Contaminant Removal
Author: Detlef R. U. Knappe
Publisher: IWA Publishing
Total Pages: 100
Release: 2004-01-01
Genre: Science
ISBN: 1843398419

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

Adsorption Technology in Water Treatment

Adsorption Technology in Water Treatment
Author: Eckhard Worch
Publisher: Walter de Gruyter
Total Pages: 344
Release: 2012-08-31
Genre: Science
ISBN: 3110240238

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.

Effects of Activated Carbon Surface Chemistry and Pore Structure on the Adsorption of Trace Organic Contaminants from Aqueous Solution

Effects of Activated Carbon Surface Chemistry and Pore Structure on the Adsorption of Trace Organic Contaminants from Aqueous Solution
Author:
Publisher:
Total Pages:
Release: 2002
Genre:
ISBN:

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.

Chemicals as Intentional and Accidental Global Environmental Threats

Chemicals as Intentional and Accidental Global Environmental Threats
Author: Elisabeta Chirila
Publisher: Springer Science & Business Media
Total Pages: 518
Release: 2007-01-15
Genre: Science
ISBN: 1402050984

This multidisciplinary book presents a critical assessment of our knowledge of chemical threats to environmental security, with special reference to prevention of chemical releases, rapid detection, risk assessment and effective management of emergency situations and long-term consequences of chemical releases. The technologies evaluated concern mainly prevention and management of both intentional and accident releases of chemicals into the environment. The book features contributors from a range of relevant scientific fields.

Tailoring of the Activation Process of Carbonaceous Adsorbents for Improving Their Adsorption Effectiveness

Tailoring of the Activation Process of Carbonaceous Adsorbents for Improving Their Adsorption Effectiveness
Author: Liang Yan
Publisher:
Total Pages: 230
Release: 2014
Genre:
ISBN:

Activated carbon adsorption is widely used to remove organic matters (both micropollutants and dissolved natural organic matter (DOM)) in water treatment systems. However, economic use and adsorption effectiveness have been major concerns due to not ideal physicochemical characteristics of most current activated carbons. Meanwhile, due to the competitive adsorption effect from DOM, it has been a great challenge to achieve effective micropollutants removal. Therefore, the main objective of this study was to develop activated carbon with specific selectivity for the removal of DOM and another type for effective removal of micropollutants. This will eventually lead to their application in water treatment facility as a sequence of two adsorber beds in series. Chemical activation of bituminous coal by KOH was applied to develop activated carbons. A total of 24 activated carbons with different porous structure and BET surface area were created under different activation conditions. The effect of the different variables of the activation process on critical carbon parameters was analyzed. In this study, phenolic compounds were selected as model compounds to represent micropollutants. In case of phenolic compounds, the oligomerization phenomenon that occurs in the presence of molecular oxygen, must be controlled by limiting the pore size of activated carbon. Therefore, BC-21 with highest microporosity was selected for phenolic compounds removal. In order to understand the impact of BC-21 on oligomerization of phenolics, single solute, binary solute and ternary solute isotherm adsorption were conducted. Meanwhile, commercial activated carbon F400 was used for comparison. These isotherms were collected under anoxic (absence of molecular oxygen) and oxic (presence of molecular oxygen) conditions. All isotherms demonstrated BC-21 has not only better adsorption capacity but also higher regeneration efficiency. BC-41 with highest mesoporosity was used as carbon precursor for DOM removal. Two novel tailoring methods (outgassing and manganese impregnation) were employed to modify the surface chemical characteristics of BC-41. The developed tailored activated carbons (BC-41-OG -argon outgassed and BC-41-MnN - manganese dioxide impregnated) showed much better DOM adsorption rate and equilibrium capacity than F400 and virgin carbon BC-41. The enhanced DOM removal by BC-41-MnN was attributed to the presence of manganese species on the carbon surface. The higher removal of BC-41-OG was due to the higher surface basicity created during the outgassing treatment. It is very common to have micropollutants such as phenolics in the treatment environment. Therefore, the role of phenolic compounds in determining the adsorption effectiveness of DOM using BC-41-OG and BC-41-MnN was further investigated. The results of the kinetic study indicated phenolic compounds have a significant positive effect on the removal rate of DOM. However, the effect on adsorptive capacity of DOM is highly dependent on the surface chemical characteristics of activated carbon. In addition, DOM with different molecular weight distribution demonstrated different extent of influence from oligomerization. The adsorption performance of BC-41-OG and BC-41-MnN was also examined by conducting small column study. The enhanced selectivity in the removal of DOM rather than phenolics was observed for both novel tailored activated carbon as compared to F400.

Adsorption of Organic and Emerging Pollutants on Carbon Materials in Aqueous Media : Environmental Implications

Adsorption of Organic and Emerging Pollutants on Carbon Materials in Aqueous Media : Environmental Implications
Author: Jordi Lladó Valero
Publisher:
Total Pages: 299
Release: 2016
Genre:
ISBN:

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.