Apart from calcium oxide, copper oxide is a popular chemical
used to impregnate with activated carbon. One of lignocellulosic
material used was coconut shell that has been impregnated using
copper oxide via steam activation [53,58]. The optimum surface
area of CuO/AC obtained was 1054 m2/g at 3 wt% of copper oxide
[53]. In the study, it was observed that the original activated
carbon had high surface area and well developed porosity
compared to copper oxide impregnated sample [53]. This was
due to the pore blockage caused by copper oxide particles after
calcinations at 450 8C. However, CuO/AC was found to have
increased SO2 adsorption capacity of 116 mg SO2/g, with copper
particles acting as active sites for the oxidation of SO2. Surface