REMOVAL OF HEAVY METALS (CADMIUM AND ZINC IONS) FROM AQUEOUS SOLUTION USING TREATED POWDERED PLANTAIN(Musa Paradisiaca) STALK AS ADSORBENT

Abstract

Powdered plantain stalk (Musa Paradisiaca) was prepared and treated with 1M sodium hydroxide solution. The plantain stalk was washed, sun-dried for 48 hrs and oven dried for 72hrs at 80oC. The treated powdered plantain stalk was used for adsorption studies of Zn (II) and Cd (II) ions from aqueous solutions of their salts. AAS (GBC 908 AA)) was used to determine the metal ion concentrations. Effect of pH, contact time, adsorbent dosage and initial ion concentration were carried out. The results obtained are: For effect of pH, the percentage adsorbance of zinc ion increased from pH 2 to pH 8(93.5%-94.9%) but for cadmium ion it reduced from pH 2 to pH 4(90.4%-90.2%) and reduced again from pH 6 to pH 8(90.7%-89.5%). For effect of contact time, the percentage adsorbance of zinc ions increased from (94.6%-95.4%) and reduced at 90minutes (95.3%) and increased again at120 minutes (95.4%). For cadmium ions, contact time range was from (91.6%-90.6%) percentage adsorbance. For adsorbance dosage, zinc ions ranged from (94.1%-95.4%) and reduced for 2.0g dosage to (95.1%). The isotherm models used were; Langmuir, Freundlich and Temkin. Langmuir isotherm was found to be the best model for cadmium ion adsorption with a correlation coefficient R2 = 0.860 and for zinc ions, Freundlich isotherm model was best fitted with a correlation coefficient of R2= 0.987. For each of the parameters, adsorption of zinc ions was more compared to the adsorption of cadmium ions. The results obtained showed that treated plantain stalk with 1M NaOH solution, is a good adsorbent for zinc ions than cadmium ions.