Removal of Phenol from Aqueous Solutions by Rice Husk Ash and Activated Carbon
ABSTRACT Experiments have been conducted to examine the liquid-phase adsorption of phenol from aqueous solutions by rice husk ash and granular activated carbon. In this experiment, rice husk ash was prepared at three different temperature: 300, 00 and 500Ã‚Â°C. Batch kinetics and isotherm studies were carried out to evaluate the effect of contact time, pH, initial phenol concentration and adsorbent dose. Batch kinetic studies showed that an equilibrium time of 5 h was needed for the adsorption of 10 mg L-1 phenol concentration. Maximum phenol adsorption capacity of rice husk ashes prepared at 300, 00 and 500Ã‚Â°C and granular activated carbon was 0.951, , 0.989 and 1 mg phenol g-1 adsorbent, respectively. Batch studies indicated that the optimum pH for the adsorption of phenol was 5 at 21Ã‚Â±2Ã‚Â°C. The capacity of phenol adsorption at equilibrium increased with the increase of initial phenol concentration (10-300 mg L-1) and decreased with the increase of adsorbents dose (1-10 g L-1). Kinetics of adsorption obeyed a first order rate equation. The suitability of the Freundlich and Langmuir adsorption models to the equilibrium data were investigated for each phenol-sorbent system. The results showed that the equilibrium data for rice husk ashes prepared at 400 and 500Ã‚Â°C and granular activated carbon could be well by the Freundlich isotherm model, whereas the equilibrium data for rice husk ash prepared at 300Ã‚Â°C fitted the Langmuir isotherm model best within the concentration range studied. The studies showed that the rice husk ash could be used as a new and efficient adsorbent material for the removal of phenol from aqueous solutions.
- SourceAvailable from: Majid Kermani[show abstract] [hide abstract]
ABSTRACT: Background & Objectives: The contamination of water by organic pollutant viz. phenolic compounds is a worldwide environmental problem due to their highly toxic nature. Biosorption has been attracted as a new technique to remove these contaminants from water and wastewater. The purpose of this study was to introduce an indigenous and inexpensive adsorbent, brown algae, for removal of phenolic compounds. Material & Methods: Phenol, 2-chlorophenol and 4-chlorophenol adsorption on Cystoseira indica has been investigated using HPLC, High Performance Liquid Chromatography. Pre-treatment, protonation and chemical cross-linking with CaCl2, have been done in order to improve the stability as well as the adsorption capacity of the algal biomass. The effect of various parameters like adsorbent dose, pH, contact time and initial phenolic concentration were studied for their optimization. The equilibrium binding has been described in terms of Langmuir or Freundlich isotherms and kinetic models. Results: Data indicated that biosorption process was equilibrated for 2 hours and then desorption surpassed absorption process. Phenol showed lower elimination rate than 4-chlorophenol and 2-chlorophenol and 2-chlorophenol had most elimination. The rate of adsorption of phenol, 2-chlorophenol and 4-chlorophenol were found to be maximum at neutral pH. Equilibrium adsorption data for phenol, 2-chlorophenol and 4- chlorophenol were fitted by using Langmuir, Freundlich and Freundlich adsorption isotherms model respectively. Also it has been found that adsorption kinetics can be described according to the Pseudo-second order model, from which the R2 and the normalized standard deviation (NSD), were determined. Conclusion: The results showed reasonable adsorption capacity of Cystoseira indica brown algae and can be used as a native alternative to phenolic compounds removal from aqueous environments.Journal of North Khorasan University of Medical Sciences. 03/2013; 4(4):683-693.