International Journal of Marine Science 2015, Vol.5, No.29, 1-7
3
Figure 1 FT-IR of porcellanite powder
Fe-O group and the band at 792 cm
-1
related to the
stretching vibration Al-O group (Silverstein
et al.,
2005).
2.2
Effect of contact time
The effect of contact time on the amount of metal
ions adsorbed was investigated at different period
(5-180 min) at 25
°
C. Figure 2 shows that the metal
ions removal percentages increased with an
increase in contact time before attaining
equilibrium. The rate of metal removal is higher at
the beginning due to the large surface area of the
adsorbent being available for the adsorption of the
metal (El-Ashtoukhy
et al., 2008). Equilibrium time
was attained at 90 min for Cu(II) and 30min for
Pb(II). The removal percentage of metal ions in
porcellanite powder for Cu(II) and Pb(II) were found
to be 68.96% and 97.43% respectively.
Figure 2 Effect of contact time on adsorption of Cu, Pb ions
onto porcelanite
2.3
Effect of pH on the adsorption
pH is an important parameter for adsorption of metal
ions from aqueous solution, because it affects the
solubility of the metal ions, concentration of the
counter ions on the functional groups of the adsorbent
and degree of ionization of the adsorbate during
reaction (Adamson and Gast, 2001).The effect of pH
on the adsorption of Cu(II) and Pb(II) ions on the
porcellanite in different media (pH=2, 4, 6, 8 and 10)
was studied by using a fixed concentration 50 mg/l
and time contact of 30, 90min for Cu(II) and Pb(II) at
25
°
C respectively. Figure 3 demonstrate the influence
of pH on the adsorption.
Figure 3 Effect of pH on Cu(II) and Pb(II) adsorption on
porcellanite
The results showed an increase in the removal
percentage of Cu(II) and Pb(II) with increasing pH
values of the solution. At low pH value, binding sites
are generally protanated or positively charged by the
hydronium ions, this repulsion occurs between the
metal cation and the adsorbent. At a higher pH value,
binding sites start deprotonation, and make different
functional groups available for metal binding. In
general, cation binding increase as pH increases
(Esposito et al
.
, 2012). In addition, the solubility of
Cu(II) and Pb(II) ions are greatly decreased as the pH
increased causing an increase in the adsosption affinity
towards the porcellanite surface (Lund, 1994).
Accordingly, the subsequent experiments were done at
pH 6.5 to avoid uncertainly in results as additional
mechanism such as precipitation might play a role in
metal removal from solution.
2.4
Effect of initial concentration of Cu(II) and Pb(II)
ions
The effect of initial concentration of metal ions on the
adsorption was carried out for different initial
concentrations of metal ions in the range of
(10-100mg/l), (50-400mg/l) to Cu(II) and Pb(II),
respectively. The dependence of percent of metal ion
removal on initial concentration of metal ions is
represented in Figure 4. Percent removal was found to
be maximum at low initial concentrations of metal ions.
