Water that contains high amounts of Mg and Ca metals is hard water. The presence
of these metal ions in water prevents the water from lather formation with soap.
This leads to the consumption of large amounts of soaps which cause loss of economy.
In light of the problem, this study is conducted to investigate the capability of
cactus powder to remove Mg and Ca metals from hard water using FAAS. The result
revealed that the concentration of both Mg and Ca metals decreased as the dose of
cactus powder increased. The concentration of Mg was 5.965 ppm in the absent of
cactus powder, but it was 6.700 ppm at 0.5 g, 2.967 ppm at 1.5 g, 1.833 ppm at 2.5
g, 2.200 ppm at 3.5 g and 1.900 ppm at 4.5 g of cactus powder. In parallel way,
the concentration of Ca was 4.967 ppm in the absent of cactus powder, but it decreased
as 3.067 ppm at 0.5 g, 1.667 ppm at 1.5 g, 0.933 ppm at 2.5 g, 0.967 ppm at 3.5
g and 1.033 ppm at 4.5 g with cactus powder. The percentage removal of both Mg and
Ca metals from hard water increased as the dose of cactus powder increased. The
percentage removal efficiency of cactus powder increased from 0.00% to 68.2% for
Mg metal, and from 0.00% to 79.2% for Ca metal as the dose of cactus powder increased
from 0.0 g to 4.5g, respectively. The percentage
removal of Ca metal increased with contact time as 27.89% at 1 hr, 38.69%
at 2 hr, 53.27% at 3 hr, 71.11% at 4 hr and 71.53% at 5 hr. In the same way, the
percentage removal of Mg metal increased with contact time as 16.00% at 1 hr, 32.84%
at 2 hr, 48.00% at 3 hr, 61.00% at 4 hr and 57.00% at 5 hr. Thus, cactus powder
has the capability to remove Ca and Mg metal ions from hard water due to the accessibility
of its active sites.