"Phenols are classified to be one of the most hazardous pollutants found in wastewater. They are discharged into rivers, lakes and seas, causing adverse effects on the environmental and human health. Adsorption is a well-known technique used to treat wastewater. Activated carbon fibers (ACFs) are highly microporous efficient adsorbents due to their small diameters, high surface area and excellent volumetric capacity. In this work, ACFs were produced using polyacrylonitrile (PAN) fibers using different methods and tools. The fibers were stabilized initially at 250 °C followed by carbonization at 850°C at a heating rate of 10°C/min and under the flow of nitrogen gas at a flow rate of 135ml/min. The carbonized fibers were subjected to physical (carbon dioxide) and chemical (potassium hydroxide) activation. The results showed that chemical activation using 3:1 ratio of KOH(wt/wt) produced fibers with a higher surface area of 2885m2/g compared to the physically activated fibers (774m2/g). The synthesized ACFs (Syn-ACFs) were compared and characterized in terms of morphology, thermal stability, composition and pore characteristics using SEM, EDS, TGA, CHN and nitrogen isotherm (Quantachrome). Bench scale batch experiments were carried out to determine and compare the adsorption efficiency, optimum parameters and the capacity of Syn-ACF and commercial ACFs (C-ACFs) for p-cresol removal. The adsorption optimum conditions using Syn-ACFs are: Syn-ACFs dosage = 1 g/l, contact time = 30 minutes, temperature = 25°C and initial pH = 4.6. The adsorption study on (Syn-ACFs) gave a higher removal efficiency of 91.0% of p-cresol compared to 71.6% (C-ACFs) at a concentration of 350ppm. In addition, the adsorption isotherms of p-cresol on C-ACFs and Syn-ACFs were found to follow the Langmuir isotherm equation; however, Syn-ACFs revealed a higher adsorption capacity (500mg/g) compared to C-ACFs (294 mg/g) at 25°C.The Syn-ACFs regeneration method was evaluated thermally at elevated temperatures and chemically using ethanol and n-hexane solvents. The thermal regeneration at 600°C achieved a higher removal efficiency of 84% compared to n-hexane (78%). The Syn-ACFs were evaluated for the treatment of produced water to ensure a removal of 71.2%. The results indicated that Syn-ACFs could be used as an efficient adsorbent for p-cresol removal in wastewater."--Abstract.

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

Mots-clés de l'auteur: adsorption ; VOC ; activated carbon fibers ; zeolites ; surface functionalization.

Activated Carbon Fiber and Textiles provides systematic coverage of the fundamentals, properties, and current and emerging applications of carbon fiber textiles in a single volume, providing industry professionals and academics working in the field with a broader understanding of these materials. Part I discusses carbon fiber principles and production, including precursors and pyrolysis, carbon fiber spinning, and carbonization and activation. Part II provides more detailed analysis of the key properties of carbon fiber textiles, including their thermal, acoustic, electrical, adsorption, and mechanical behaviors. The final section covers applications of carbon fiber such as filtration, energy protection, and energy and gas storage. - Features input from an editor who is an expert in his field: Professor Jonathan Chen has a wealth of experience in the area of activated carbon fiber materials - Provides systematic and comprehensive coverage of the key aspects of activated carbon fiber textiles, from their principles, processing, and properties to their industrial applications - Offers up-to-date coverage of new technology for the fiber and textiles industries - Covers applications such as filtration, energy protection, and energy and gas storage

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