The influence of impregnating chemicals on the carbonization process of viscose fiber cloths
Abstract
The influence of some chemical impregnating such as polyphosphate urea, ZnCl2, AlCl3, FeCl3, H2NaPO4, H3PO4 on the carbonization process of viscose fiber cloth at the temperature range from 30 to 700 0C was studied in detail. By the thermalgravimetric analysis, the obtained results have showed that the presence of these chemical impreganating agents caused lowering the activation energy and increasing the carbonization viscose mass left at 7000C. The polyphosphate urea was proven to be a good chemical agent for the carbonization process.
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Introduction
Activated carbon such as powdered or granular forms is well known owing to its widespread application in many fields as a exellent adsorbent for purification, remediation of wastewater and toxic gas generated in industry [1-4]. In the recent years the activated carbon fiber cloths have receive an increasing concern because they exhibit a comparative advantages over the traditional activated carbon, including their application in high technological inovation as use in cell therapy as a support for stem cell growth [5]. Besides, activated carbon fiber cloths belong to the light stable materials with the higher surface area and pore volume that are easily used in different objectives [5]. The activated carbon fiber cloths are resulting from two main processes including physical or thermal and chemical activation [5]. Physical activation involves two stages such as pyrolysis of the fabric used as a precursor, then followe gasifiction with and oxidizing gas like steam or carbon dioxide [6]. On the other hand, the chemical activation process used for preparation of activated carbon cloths consists of (i) impregnation of the precursor with a Lewis acid such as ZnCl2, AlCl3, H3PO4, (ii) pyrolysis of the impregnated precursor, (iii) washing of the obtained product to eliminate the remaining impregnating chemicals before it is allowed to dry. However, in the pyrolysis process there are two steps. The former step is precursor carbon fiber cloth cabonized to remove hydrate and volatile substance, while, the latter is a process of carbonized fiber cloth is activating. The practice has indicated that the role of impregnating agents is essential issues in preparation of carbonization carbon fiber cloths [4]. In this aricle, the influence of impregnating agents such as FeCl3, AlCl3, ZnCl2, Na2HPO4, H3PO4, polyphosphate urea on the chemical the carbonzation process of viscose fiber cloth was studied in detail. It includs their influence on the main factors about kinetics and thermdynamics of carbonization process. The influence of the impregnating agent on carbonizing process was determined based on the kinetics analysis, using thermogravimetric analysis (TGA) and Kissinger equation.
Conclusion
The study of the influence of chemical impregnating on viscose fiber cloth was carried out in detail. The chemical impregnating agents such as polyphosphate urea, ZnCl2, FeCl3, AlCl3, Na2HPO4 and H3PO4 have been used as chemical agents for carbonization process of viscose fiber cloth. The presence of these agents might cause the change in the mass of viscose fiber remaining after carbonization at temperature from 30 to 7000C. The carbonization process of viscose fiber occurred spontaneously and along endothermic reaction. The main effect of chemical agents is to lowering the carbonization temperature of impregnated viscose fiber comparing with precursor. The chemical agent as polyphosphate urea was proven with the most effective advantage in carbonization of viscose fiber with the highest mass left reached to 39%.