The potential of sodium hydroxide (NaOH) modified Petai Belalang (Leucaenaleucocephala) leaf powder as a biosorbent for methylene blue removal from aqueous solutions was investigated. Adsorption parameters studied include initial dye concentration, pH, dosage, kinetics and isotherms. The pHzpc of chemically treated Leucaenaleucocephala leaf powder was 7.50 and adsorption equilibrium time was achieved after 60 min. The kinetic data was best represented by the pseudo-second order model. The maximum adsorption capacity predicted from Langmuir model was 208.33 mg g-1. This work indicated that NaOH treated Leucaenaleucocephala leaf powder can be an attractive biosorbent for MB removal from diluted industrial wastewater.

Abstract. Sulfuric acid treated Petai belalang (Leucaena leucocephala) leaf powder (SLLP) was used as an adsorbent for Pb(II) ions removal. The experimental adsorption parameters investigated include pH, dosage and initial Pb(II) concentration. Pb(II) removal was more favored at a higher adsorbent dosage, pH and temperature. Adsorption kinetics conformed to the pseudo-second order model while Langmuir isotherm model recorded the value of maximum adsorption capacity (q max) of 222 mg/g. The major functional groups involved in the adsorption process were identified as hydroxyl, amino and ether as revealed by the FTIR analysis. The prepared adsorbent demonstrated a potential application for efficient removal of Pb(II) ions from industrial wastewater.