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Articles by W.S.W. Ngah
Total Records ( 2 ) for W.S.W. Ngah
  M.A.K.M. Hanafiah , W.S.W. Ngah , S.C. Ibrahim , H. Zakaria and W.A.H.W. Ilias
  The ability of rubber or Hevea Brasiliensis (HB) leaf powder to adsorb Pb2+ from aqueous solution has been investigated through batch experiments. The Pb2+ adsorption was found to be dependent on contact time, initial Pb2+ concentration and temperature. The kinetic processes of Pb2+ adsorption onto HB leaf powder were described by applying pseudo-first-order and pseudo-second-order rate equations. The kinetics data for the adsorption process obeyed pseudo-second-order equation. The equilibrium data were described well by the Langmuir and Freundlich isotherms. The maximum adsorption capacity determined from the Langmuir isotherm was found to be 46.73 mg g-1 at 303 K. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were also calculated. The adsorption process was found to be exothermic and spontaneous in nature. The studies showed that HB leaf powder could be used as a good adsorbent material for Pb2+ removal from aqueous solution.
  W.K.A.W.M. Khalir , M.A.K.M. Hanafiah , S.Z.M. So`ad , W.S.W. Ngah and Z.A.A. Majid
  Rubber (Hevea brasiliensis) leaf powder was modified by xanthation process and its potential in removing toxic Pb(II) ion from aqueous solutions was investigated in batch and column experiments. Pb(II) adsorption efficiency was found to be affected by several physicochemical parameters such as adsorbent dosage, shaking rate and temperature. The optimum adsorbent dosage was found to be at 0.02 g with more than 80% Pb(II) removal. The amount of Pb(II) adsorbed (mg g-1) increased with increasing shaking rate but decreased with increasing adsorbent dosage and temperature. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) were computed and Pb(II) adsorption process was found to be exothermic. Fixed-bed column fitted well the Thomas and Yoon-Nelson models with correlation coefficients of R2>0.96.
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