REMOVAL OF DIVALENT NICKEL FROM AQUEOUS SOLUTIONS BY ADSORPTION ONTO MODIFIED HOLLY SAWDUST: EQUILIBRIUM AND KINETICS

Abstract

The removal of divalent nickel from aqueous solutions on modified
holly sawdust was studied at varying contact times, pH, initial divalent
nickel concentrations and adsorbent dose. Results showed the removal
efficiency by increasing of pH increased and decreased with initial
nickel divalent concentration. By increasing pH from 2 to 12
(equilibrium time= 240 min, adsorbent dose= 0.6g/100 mL, divalent nickel
concentrations= 60 mg/L), the removal efficiency increased from 17.47 %
to 81.76 %. Also removal efficiency was decreased from 98 % to 19.3 %
by increasing of initial divalent nickel concentrations from 20 mg/l to
100 mg/L. Also the results showed the removal efficiency was increased
by increasing of adsorbent dose and contact time. By increasing of
adsorbent dose from 0.2 g/100CC to 1 g/100CC, the removal efficiency
increased from 32.78% to 99.98%. The removal efficiency increased from
34.7% to 83.67% by increasing of contact time from 5 min to 240 min.
Experimental equilibrium and kinetics data were fitted by Langmuir and
Freundlich isotherms and pseudo-first-order and pseudo-second-order
kinetics models, respectively. The results show that the equilibrium
data follow Langmuir isotherm and the kinetic data follow
pseudo-second-order model. The obtained maximum adsorption capacity was
22.47 mg/g at a pH 7. The results show that the modified holly sawdust
can be used for the treatment of aqueous solutions containing nickel as a
low cost adsorbent.