Water Filter Fabrication from a Mixture of KMnO₄ Modified Kapok Carbon Fiber, Zeolite, Bentonite and Clay for Fe³⁺Removal and Water Hardness Treatment

Abstract

A water filter was fabricated from a mixture of KMnO₄ modified kapok carbon fiber, zeolite, bentonite and kaolinite clay for Fe³⁺ removal and water hardness treatment. The effects of amount of KMnO₄ modified kapok carbon fiber (30-60 wt%), zeolite (20-40 wt%) and sintering temperature (500-700°C) on the properties of sintered products were evaluated. The best of sintered products were tested for treatment of solutions with 5 mg L^-1 Fe³⁺ and 40-200 mg L^-1 total water hardness. The results show that the physical properties of the sintered products were affected by the contents of KMnO₄ modified kapok carbon fiber and sintering temperature. The linear drying shrinkages of the mixture of raw materials increase with increasing content of modified kapok carbon fiber amounts due to the effect of water amount used for mixing process. Furthermore, firing shrinkages of sintered products increased with increasing sintering temperature for the same ratio of raw materials. Finally, the firing shrinkages and density of sintered products decrease with increasing content of the modified kapok carbon fiber at constant sintering temperature. It was shown that the sintered product made with 40 wt% of KMnO₄ modified kapok carbon fiber and sintered at 600°C is suitable for filter fabrication. The KMnO₄ modified kapok carbon fiber filter could adsorb 5-6% more Fe³⁺ at equilibrium than filter made with kapok carbon fiber. The Fe³⁺ was removed by adsorption and precipitation processes. The Fe³⁺ adsorption process of modified kapok carbon fiber filter was fitted to the Langmuir model with maximum adsorption capacity of 53.76 mg g^-1. For hardness removal, the Ca²⁺, Mg²⁺ and HCO₃ˉ ions removal capacities from solutions of total hardness in the range 40-200 mg L^-1 by modified kapok carbon fiber filter are 4.49-19.21 mg g^-1 for Ca²⁺, 1.55- 5.31 mg g^-1 for Mg²⁺ and 28.1-123.5 mg g^-1 for HCO₃ˉ, respectively.