SUMMARY
A respirator is a device designed to protect the wearer from inhaling harmful substances such as dust, fumes, vapors, and/or gases. Generally, a respirator can be grouped into two categories which are air purified respirator (APR) and air supply respirator (ASR). Air purifying respirator removes contaminants from air by passing the ambient air through the air-purifying element before it reaches the user. Besides, the air supplying respirator supplies clean air to a user through an air-supply hose. Air supply respirator consists of the face mask, air cylinder, and regulator. By having air cylinder, air supply respirator can operates up to 45 minutes. However, there are few drawbacks associated in designing an appropriate air-supply respirator which are short duration of operation and not very practical to be used due to the heavy weight of air cylinder. In order to design a flexible and practical air-supply material, this research was conducted to modify the physical and structural properties of a low-cost green-based adsorbent for oxygen adsorption application. To complete this aim, paddy husk was modified using acid and alkaline-based activated carbon (AC) to improve the surface area and porosity volume of modified-sorbent. The morphological and structural analysis were accomplished with the helped of variable pressure scanning electron microscopic, elemental dispersion x-ray analyser, and Fourier transform infrared spectroscopy. The analysis showed that the acid and alkaline functionalized on the activated carbon burnt paddy husk affects the properties of surface sorbent. The oxygen adsorption and desorption studies were conducted in a single cyclical operation. Results gained from this study revealed that the acid-AC burnt paddy husk record the highest oxygen adsorption capacity at 3 bar which is 38.1240 mmol/g, whilst the alkaline-AC burnt paddy husk sorbent able to adsorb 31.6036 mmol/g oxygen at 5 bar. Thus, this study established that the surface chemistry modification done on the burnt paddy husk gives a reasonable effect to the oxygen adsorption capacity.