Abstract:
Acacia bark (Acacia crassicarpa sp) contains cellulose, lignin and tannin which
have the potential to be used as adsorbents in the form of charcoal. Acacia bark
charcoal is used as an adsorbent in the adsorption of lead(II) ions. This research
aims to determine the highest adsorption capacity and efficiency of acacia bark
charcoal in adsorbing lead(II) ions with optimization conditions for pH, contact
time and adsorbate concentration. Acacia bark charcoal is made through a
carbonization process at 800ºC for 90 minutes. Acacia bark charcoal was
characterized by referring to SNI 06-3730-1995 to determine water content, ash
content, iodine adsorption capacity and methylene blue adsorption capacity.
Characterization of charcoal functional groups before and after adsorption was
analyzed using FTIR, surface morphology and elemental composition of charcoal
before adsorption were analyzed using SEM-EDS. The concentration of the
lead(II) ion solution before and after adsorption was analyzed using AAS. The
adsorption process in this research uses a batch system. The yield of acacia bark
charcoal was 27.2313%. The results of the characterization of SNI 06-3730-1995
for charcoal showed that the water content was 5.79%, the ash content was 4.83%,
the iodine adsorption capacity was 899.1044 mg/g and the methylene blue
adsorption capacity was 25.0078 mg/g. The optimum adsorption conditions were
obtained at pH 6, contact time of 50 minutes and adsorbate concentration of 40
mg/L with adsorption efficiency reaching 99.67% and adsorption capacity of
1.6605 mg/g. FTIR results show that the functional groups contained in acacia
bark charcoal before and after adsorption are almost the same, but there is one
functional group that is only found in charcoal after adsorption, namely O-Pb.
SEM-EDS results show that charcoal before adsorption has more pores and a
rough surface with the elements contained consisting of C, O and K.
