| Summary: | Modified commercial natural zeolite with a coating method of iron oxide
has been conducted by hydrolysis of Fe3+ solution and NaOH. The modified
zeolite was characterized using X-ray diffraction (XRD), while functional groups
were identified by infra-red spectrophotometer (IR). The modified zeolite was
used to adsorb phosphate ion from the solution using comparator adsorbent of
Rowapos (β-FeOOH granular). The observed adsorption parameters were pH,
contact time, adsorbent mass, phosphate ion concentration and solution types.
The result of X-ray diffraction showed 3 major peaks in diffractogram in
the diffraction angle (2θ) of 22.3411°, 27.8800° and 9.9150° which correspond to
d values 3.9761, 3.1975 and 8.91378 �, respectively, indicated that the natural
zeolite was clinoptilolite type material. The adsorption process of phosphate ion
had the highest adsorption percentage (88.6%) occurred at pH 3.02 with a mass of
300 mg adsorbent, initial solution concentration of 2.5 mg.L-1 and contact time of
120 min. The adsorption process of phosphate ion in freshwater was in accordance
with kinetic equation pseudo-second-order (Ho) with the k2 value for ZM was
25.96 g.mg-1.min-1 and for Rowaphos was 14.68 g.mg-1.min-1 with adsorption
capacities of 0.69 mg.g-1for ZM and 0.87 mg.g-1 for Rowaphos. The adsorption of
phosphate ion in saltwater followed kinetic equation pseudo-first- order
(Lagergren) with the k1 value for ZM was 0.0051 min-1 and for Rowaphos is
0.0421 min-1 with adsorption capacities of 0.21 mg.g-1 for ZM and 0.91 mg.g-1
for Rowaphos. Phosphate ion adsorption process by ZM and Rowaphos both in
freshwater and saltwater was dominated by physisorption with the mean free
energy (ED) value < 8 kJ.mol-1 and heat sorption (B) dan �G values are < 20
kJ.mol-1.
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