Adsorption capacity of Kenaf fibers (Hibiscus Cannabinus L.) in lead aqueous solution

The unregulated effluent coming from recycling industries has been tremendously affecting nearby river systems. It is also one of the major contributors to water pollution due to increasing concentration disposal of heavy toxic metals coming from the effluent. In the report of Greenpeace, the discharge outlet from one of the biggest lead recycling industry amounted to as high as 190 ppm. This study delved into the potential and effectiveness of using Kenaf fibers as an adsorbent for a post treatment process. The effluent was simulated through the use of a lead nitrate aqueous solution. The determination of adsorbent loading for maximum removal was determined by varying the weight of the adsorbent, contact time, while maintaining the initial concentration constant at190 ppm, and volume at 100 mL. The adsorbent loading for maximum removal was 7.5 grams and the contact time to reach the break through was 3 hours these data were used for the actual test runs. At a pH of 2.2, 3 hours contact time, 190 ppm initial concentration and 7.5 grams of adsorbent loading, it was observed that a maximum removal of 40.91% was achieved. To further enhance the effectiveness of Kenaf fibers at pH of optimal removal as discussed by the different literatures, the removal of lead was also tested at pH 5.2. At a higher level of pH, higher percent removal was achieved amounting to 92.71% for 160 ppm initial concentration at a pH of 5.44. The Freundlich isotherm was more favorable at pH 5.2 which gave an R2 value of 0.9671. The adsorption capacity of Kenaf fibers at pH 5.2 based from the Freundich Isotherm was computed to be 0.26 (mg adsorbate/g Kenaf fibers) (L of water/mg adsorbate) 0.8029 A pH 6.7, a higher percentage removal occurred as compared to a pH of. 5.2. The percent removal reached as high as 98.26% for 130 ppm initial concentration. Also, a trend of decreasing concentration with increasing percentage removal was exhibited. The Langmuir isotherm was more favorable at pH of 6.7 which gave an R2 value of 0.9971. The adsorption capacity of Kenaf fibers at ph 6.7 based from the Langmuir Isotherm is 3.56 mg/g