Impact of Surface Chemistry on Adsorption: Tailoring of Activated Carbon

Impact of Surface Chemistry on Adsorption: Tailoring of Activated Carbon
Author: Morgana T. Bach
Publisher:
Total Pages: 132
Release: 2007
Genre:
ISBN:

The present work summarizes research into the impact of the surface chemistry of activated carbon on the water treatment phenomena of pH excursions, the tailoring of activated carbon through manipulation of the dissolved oxygen (DO) content of the water used to create steam for activation, and, most importantly, the impact of these changes in surface chemistry on adsorption.

Improving Adsorption of Perfluoroalkyl Acids by Tailoring Surface Chemistry of Activated Carbon and Electric Potentials

Improving Adsorption of Perfluoroalkyl Acids by Tailoring Surface Chemistry of Activated Carbon and Electric Potentials
Author: Navid Saeidi
Publisher:
Total Pages:
Release: 2021
Genre:
ISBN:

The subject of the present thesis is enhancing adsorption of perfluoroalkyl acids (PFAAs) from water on activated carbon (AC) and developing an approach for on-site regeneration of the AC saturated with the compounds. Adsorption of PFAAs on AC is the most common technology for remediation of water contaminated with these compounds. However, there are some drawbacks, e.g. largely differing adsorption performances of various ACs for PFAAs, very low adsorption affinity of short-chain PFAAs and lack of on-site techniques for regeneration of exhausted AC, which reduce the overall efficiency of this technique. In addition, adsorption of PFAAs must be considered as a relocation of the pollutants, not yet their final elimination. With the aim of mitigating the problems mentioned above, this thesis has focused on (i) understanding the effect of AC properties on adsorption of PFAAs, (ii) modifying AC with targeted functional groups for enhancing its affinity towards short- and long-chain PFAAs, (iii) a deeper insight into adsorption mechanism of PFAAs on AC and (iv) developing an electrochemical-based approach for controlling adsorption/desorption of PFAAs on AC. Adsorption of PFAAs was correlated with physical and surface chemical properties of well characterised activated carbon felts (ACFs). The surface chemical properties which were crucial for very high adsorption affinity of ACFs were identified. Targeted modifications were applied to develop the desired surface chemistry on ACF. The modified ACF exposes very high affinity and capacity for short- and long-chain PFAAs even in presence of competitive organic and inorganic ions and in a wide range of pH values. A deeper mechanistic study was performed by a direct comparison between adsorption behaviour of PFAAs with phenanthrene as a nonionic adsorbate and octanoic acid as F-free analogon of perflurooctanoic acid (PFOA). External electrical potential was applied to control adsorption of PFAAs on various ACFs, enabling not only to improve adsorption of PFAAs but also to desorb PFAAs from saturated ACFs. A long-term (around 1000 h) electrosorption/electrodesorption of PFOA with negligible loss of performance of the operational cell was obtained. On account of this, we consider the present study as a significant step forward toward enhancement of adsorption technologies in removal of PFAAs from water.

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.

Activated Carbon Surfaces in Environmental Remediation

Activated Carbon Surfaces in Environmental Remediation
Author: Teresa J. Bandosz
Publisher: Elsevier
Total Pages: 587
Release: 2006-02-27
Genre: Technology & Engineering
ISBN: 0080455956

Activated Carbon Surfaces in Environmental Remediation provides a comprehensive summary of the environmental applications of activated carbons. In order to understand the removal of contaminants and pollutants on activated carbons, the theoretical bases of adsorption phenomena are discussed. The effects of pore structure and surface chemistry are also addressed from both science and engineering perspectives. Each chapter provides examples of real applications with an emphasis on the role of the carbon surface in adsorption or reactive adsorption. The practical aspects addressed in this book cover the broad spectrum of applications from air and water cleaning and energy storage to warfare gas removal and biomedical applications. This book can serve as a handbook or reference book for graduate students, researchers and practitioners with an interest in filtration, water treatment, adsorbents and air cleaning, in addition to environmental policies and regulations. Addresses fundamental carbon science and how it relates to applications of carbon surfaces Describes the broad spectrum of activated carbon applications in environmental remediation Serves as a handbook or reference book for graduate students, researchers and practitioners in the field

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 by Carbons

Adsorption by Carbons
Author: Eduardo J. Bottani
Publisher: Elsevier
Total Pages: 773
Release: 2011-10-10
Genre: Technology & Engineering
ISBN: 0080559425

Adsorption by Carbons covers the most significant aspects of adsorption by carbons, attempting to fill the existing gap between the fields of adsorption and carbonaceous materials. Both basic and applied aspects are presented. The first section of the book introduces physical adsorption and carbonaceous materials, and is followed by a section concerning the fundamentals of adsorption by carbons. This leads to development of a series of theoretical concepts that serve as an introduction to the following section in which adsorption is mainly envisaged as a tool to characterize the porous texture and surface chemistry of carbons. Particular attention is paid to some novel nanocarbons, and the electrochemistry of adsorption by carbons is also addressed. Finally, several important technological applications of gas and liquid adsorption by carbons in areas such as environmental protection and energy storage constitute the last section of the book. The first book to address the interplay between carbonaceous materials and adsorption Includes important environmental applications, such as the removal of volatile organic compounds from polluted atmospheres Covers both gas-solid and liquid-solid adsorption

Foundations of Nanotechnology - Three Volume Set

Foundations of Nanotechnology - Three Volume Set
Author: A. K. Haghi
Publisher: CRC Press
Total Pages: 995
Release: 2015-05-30
Genre: Science
ISBN: 1498757073

Nanoscale science, engineering, and technology-commonly referred to collectively as nanotechnology-is believed by many to offer extraordinary economic and societal benefits. Nanotechnology is generally defined as the ability to create and use materials, devices, and systems with unique properties at the scale of approximately 1 to 100 nm. Nanotechn

Green Carbon Materials

Green Carbon Materials
Author: Thomas E. Rufford
Publisher: CRC Press
Total Pages: 291
Release: 2014-03-06
Genre: Science
ISBN: 9814411140

Agricultural and food industry waste materials have been an important feedstock for activated carbon production for many years. In the development of cleaner energy production and utilization processes, new advanced carbon materials with enhanced properties have been studied. Techniques to tailor pore structure and surface chemistry can produce bet