Preparation, Characterization and Application of Activated Carbon for Arsenic Separation from Water

Abstract

Arsenic removal from water in the form of As(III) and As(V) using activated carbon and iron loaded activated carbon has been studied. Activated carbon has been prepared from jute stick using both chemical activation and physical activation methods. In chemical activation, H3P04 was used as an activating agent while in physical activation steam was used. The activated carbons produced were characterized by determining BET surface area, iodine value, methylene blue dye number, reactivity, pore volume and pore size. In addition, the studies on structural feature, surface functionality and morphology were also carried out using Raman spectroscopy, FT-IR spectroscopy and Scanning Electron Microscopy (SEM). The maximum BET surface area, iodine value and methylene blue number were found to be 1664 m2/g, 1440 mg/g and 475 mg/g, respectively. Activated carbon produced at optimum conditions was used for As(III) and As(V) separation from water in different method, such as batch process, continuous column filtration method and commercial filter method. Around 48% of As(l11) separation while complete removal of As(V) was achieved using chemically activated carbon (ACC) in column filtration method. However, the main objective of this work is to remove As(III) to an acceptable range (below 0.01 ppm), which is the predominant species in the most underground water, especially in Bangladesh. To enhance the arsenic adsorption capacity, iron species was loaded onto the ACC as well as physically activated carbon (ACS). The iron loaded activated carbon F ACC exhibited superior performance in As(III) separation in column filtration method. Almost complete removal of As(III) was achieved when 9 cm of bed thickness using 1.5 g of F ACC was used in a glass column. However, in order F ACC to utilize in practical filtration of arsenic contaminated water an investigation in the scale of 24 L/day of water, a minimum requirement of commercial filtration, was perfonned. In this study a commercial house hold filter body was used after removing the ceramic candleand layers of filter cartridge. The F ACC was filled in the blank filter cartridge and used for filtration. To compare the separation capacity ofFACC, ACC and FACS were also used in the commercial filtration method. The F ACC showed the dominant performance and almost 99% arsenic was removed from the water. Based on the characterization data, F ACC poses much higher BET surface area, micropore surface area and micropore volume which mainly contributed in liquid phase adsorption. In addition, surface polarity due to the presence of functional groups on ACC contributed to widely distribute of iron species on the surface which in turn contributed to efficiently adsorb As(III) from water. Finally, this study embarked an efficient way of As(III) and As(V) separation from water which can be recommended to commercially use for drinking water purification, especially in the countries where arsenic contamination in drinking water created a public health problems.