Preparation Of Activated Carbon Fibers Research Articles

Adsorption of caffeine on mesoporous activated carbon fibers prepared from pineapple plant leaves

The present work reports the preparation of activated carbon fibers (ACFs) from pineapple plant leaves, and its application on caffeine (CFN) removal from aqueous solution. The preparation procedure was carried out using the H3PO4 as activating agent and slow pyrolysis under N2 atmosphere. The characterization of materials was performed from the N2 adsorption and desorption isotherms, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, Boehm titration and pHpzc method. ACFs showed high BET surface area value (SBET = 1031m2 g−1), well-developed mesoporous structure (mesopore volume of 1.27cm³ g−1) and pores with average diameter (DM) of 5.87nm. Additionally, ACFs showed features of fibrous material with predominance of acid groups on its surface. Adsorption studies indicated that the pseudo-second order kinetic and Langmuir isotherm models were that best fitted to the experimental data. The monolayer adsorption capacity was found to be 155.50mgg−1. thermodynamic studies revealed that adsorption process is spontaneous, exothermic and occurs preferably via physisorption. The pineapple leaves are an efficient precursor for preparation of ACFs, which were successful applied as adsorbent material for removal of caffeine from the aqueous solutions.

Synthesis of activated carbon fibers from cotton by microwave induced H3PO4 activation

The preparation of activated carbon fiber (ACF) with cotton as raw precursor via microwave assisted H3PO4 activation was explored in the present study. The influence of microwave power, activation time and acid concentration on the properties of activated carbon fiber was investigated. The ACF with maximum surface area and total pore volume of 1370 m2/g and 0.98 cm3 was prepared at microwave input power of 640 W, activation time of 10 min and H3PO4 concentration of 50% (Wt.). The ACF was tested with methylene blue (MB) dye adsorption and the equilibrium adsorption capacity was 476 mg/g, with the adsorption isotherm following the Langmuir isotherm model. The adsorption kinetic followed the pseudo-second-order kinetic model, while the adsorption mechanism was well described by the film diffusion model. The experimental results indicated the potential of cotton as good precursor for the preparation of ACF with promising adsorption capacity by microwave heating.

리오셀 표면개질공정을 도입한 ACF 제조 및 특성

Lyocell fibers were used as a precursor in order to improve yield and strength of cellulose-based precursor while manufacturing activated carbon fiber(ACF). Lyocell fibers as a precursor for the preparation of ACF were surface-modified by reaction with 3-aminopropyltriethoxysilane(APTES) and pre-treated with KOH and H3PO4. Using aforementioned precursor, ACFs were prepared by a series of stabilization, carbonization and activation process at high temperatures. On each process, FT-IR, TGA, UTM and SEM were used to observe fibers' physical properties including structure and porous surfaces. FT-IR results proved that surface modification was achieved during stabilization, carbonization and activation process. TGA results during carbonization process found that surface modified fibers with APTES 0.02 mol(A2) showed higher thermostability, and extended pre-treatment increased yield. Especially, yield was found to have an increase of 10~20 wt% with surface modification during activation process. UTM results showed that tensile strength has the same order of concentration of APTES after surface modification, however, was found to show lower tensile strength than lyocell fibers after stabilization process. SEM results revealed that more homogeneous porosity control could be proceed after modifying the surface for the effective removal of hazardous substances.

Preparation of Micropore-Containing Adsorbents from Kenaf Fibers and Their Use in Mercury Removal from Aqueous Solution

Here, a number of activated carbon fibers (ACFs) prepared from kenaf natural fibers (KNFs) by chemical activation with KOH under different operation conditions have been used as adsorbents for the removal of mercury from aqueous solutions. Samples were characterized by N2 adsorption at 77 K, mercury porosimetry, scanning electronic microscopy (SEM), and FT-IR spectroscopy. The adsorption of mercury at 25°C without pH adjustment from an aqueous solution was evaluated from both kinetic and equilibrium standpoints. It was found that the activation conditions during the preparation of ACFs (i.e., impregnation ratios and activation temperatures) had a strong influence on the porosity of the resultant samples and, therefore, on their mercury adsorption capacity. The sample prepared at 800°C using an impregnation ratio of 3:1 (named K3-800) presented the maximum Langmuir adsorption capacity (10.53 mg/g). This sample showed a specific surface area of 881 m2/g, a micropore volume of 0.60 cm3/g, and the highest total pore volume (2.69 cm3/g).

Optimization of activated carbon fiber preparation from Kenaf using K 2HPO 4 as chemical activator for adsorption of phenolic compounds

The present work reports the preparation of activated carbon fiber (ACF) from Kenaf natural fibers. Taguchi experimental design method was used to optimize the preparation of ACF using K 2HPO 4. Optimized conditions were: carbonization at 300 °C, impregnation with 30% w/v K 2HPO 4 solution and activation at 700 °C for 2 h with the rate of achieving the activation temperature equal to 2 °C min −1. The surface characteristics of the ACF prepared at optimized conditions were also studied using pore structure analysis, scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Pore structure analysis shows that micropores constitute the most of the porosity of the prepared ACF. The ability of the ACF prepared at optimized conditions to adsorb phenol and p-nitrophenol from aqueous solution was also investigated. The equilibrium data of phenol and p-nitrophenol adsorption on the prepared ACF were well fitted to the Langmuir isotherm. The maximum adsorption capacities of phenol and p-nitrophenol on the prepared ACF are 140.84 and 136.99 mg g −1, respectively. The adsorption process follows the pseudo-first-order kinetic model.

Synthesis and characterization of activated carbon fibers from Kevlar

Kevlar [poly (p-phenilylene terephtalamide)], was used as a precursor in the preparation of acti-vated carbon fibers. For this intention, physical and chemical activations were carried out. Activated fiberswere physically prepared from the carbonization of the Kevlar and its later activation with CO 2 and steam ofwater, by the other hand; the chemically activated fibers were obtained by means of the impregnation of thematerial with phosphoric acid and their later carbonization. Different conditions were used and preliminaryanalyses of the precursor were taken into account (TGA-DTA / IR). The resulting fibers were characterizedby N 2 (77K) adsorption, infrared spectroscopy, SEM, and immersion calorimetry. Yields and Burn off werealso evaluated. The results shows that if you want to synthesize activated carbon fibers from Kevlar strongconditions respect to the commonly used such as water steam, high phosphoric acid concentrations and meth-ods of impregnation are the ones who allows the development of optimal surface areas and pore volumes.

The structural transitions of rayon under the promotion of a phosphate in the preparation of ACF

The molecular and physical structures of cellulosic rayon fiber during the stepwise heat treatment for the fabrication of activated carbon fiber (ACF) were researched by Fourier transform infrared spectroscopy, wide angle X-ray diffraction and elemental analysis. Dibasic ammonium phosphate (DAP) lowers the dehydration temperature of rayon evidently and acts also as a reactant besides as a catalyst. Group C=O is generated at 200 °C while group C=C appears at 250 °C. About 220–250 °C is a key temperature range where the chain, ring and crystal structures of rayon macromolecules are damaged completely to lose the basic characteristics of cellulose by dehydration. The drastic changes of weight loss, discoloration and shrinkage occur simultaneously. The bands of chemical groups decrease rapidly and go to disappear during carbonization. The activation at a lower temperature (750 °C) decreases the contents of oxygen-containing groups, but increases them at a higher temperature (950 °C). The microcrystalline structures are gradually formed near 800 °C and activation seems to be favor to the crystallization. A higher usage of the phosphate does not only affect the weight-losses of rayon fiber significantly, it also enhances the specific surface areas of ACF obviously.

A New Preparation Technique of Activated Carbon Fiber

AbstractIn this paper, the characteristic of a new preparation technique of activated carbon fiber (ACF) was discussed. The structures and properties of the ACF produced were investigated simultaneously. The experimental results indicated that this new technique is a high efficient method for the preparation of ACF. It needs simple facilities and is easy to be operated. The products obtained possess high specific surface area and adsorption capacity.