The effects of three preparation variables: CO(2) activation temperature, CO(2) activation time and KOH:char impregnation ratio (IR) on the 2,4,6-trichlorophenol (2,4,6-TCP) uptake and carbon yield of the activated carbon prepared from oil palm empty fruit bunch (EFB) were investigated. Based on the central composite design, two quadratic models were developed to correlate the three preparation variables to the two responses. The activated carbon preparation conditions were optimized using response surface methodology by maximizing both the 2,4,6-TCP uptake and activated carbon yield within the ranges studied. The optimum conditions for preparing activated carbon from EFB for adsorption of 2,4,6-TCP were found as follows: CO(2) activation temperature of 814 degrees C, CO(2) activation time of 1.9h and IR of 2.8, which resulted in 168.89 mg/g of 2,4,6-TCP uptake and 17.96% of activated carbon yield. The experimental results obtained agreed satisfactorily with the model predictions. The activated carbon prepared under optimum conditions was mesoporous with BET surface area of 1141 m(2)/g, total pore volume of 0.6 cm(3)/g and average pore diameter of 2.5 nm. The surface morphology and functional groups of the activated carbon were respectively determined from the scanning electron microscopy and Fourier transform infrared analysis.
The adsorption characteristics of 2,4,6-trichlorophenol (TCP) on activated carbon prepared from oil palm empty fruit bunch (EFB) were evaluated. The effects of TCP initial concentration, agitation time, solution pH and temperature on TCP adsorption were investigated. TCP adsorption uptake was found to increase with increase in initial concentration, agitation time and solution temperature whereas adsorption of TCP was more favourable at acidic pH. The adsorption equilibrium data were best represented by the Freundlich and Redlich-Peterson isotherms. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The mechanism of the adsorption process was determined from the intraparticle diffusion model. Boyd plot revealed that the adsorption of TCP on the activated carbon was mainly governed by particle diffusion. Thermodynamic parameters such as standard enthalpy (DeltaH degrees ), standard entropy (DeltaS degrees ), standard free energy (DeltaG degrees ) and activation energy were determined. The regeneration efficiency of the spent activated carbon was high, with TCP desorption of 99.6%.
Oil palm fibre was used to prepare activated carbon using physiochemical activation method which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO(2)) gasification. The effects of three preparation variables: the activation temperature, activation time and chemical impregnation (KOH:char) ratio on methylene blue (MB) uptake from aqueous solutions and activated carbon yield were investigated. Based on the central composite design (CCD), a quadratic model and a two factor interaction (2FI) model were respectively developed to correlate the preparation variables to the MB uptake and carbon yield. From the analysis of variance (ANOVA), the significant factors on each experimental design response were identified. The optimum activated carbon prepared from oil palm fibre was obtained by using activation temperature of 862 degrees C, activation time of 1h and chemical impregnation ratio of 3.1. The optimum activated carbon showed MB uptake of 203.83 mg/g and activated carbon yield of 16.50%. The equilibrium data for adsorption of MB on the optimum activated carbon were well represented by the Langmuir isotherm, giving maximum monolayer adsorption capacity as high as 400mg/g at 30 degrees C.
This study investigated the adsorption potential of oil palm shell-based activated carbon to remove 2,4,6-trichlorophenol from aqueous solution using fixed-bed adsorption column. The effects of 2,4,6-trichlorophenol inlet concentration, feed flow rate and activated carbon bed height on the breakthrough characteristics of the adsorption system were determined. The regeneration efficiency of the oil palm shell-based activated carbon was evaluated using ethanol desorption technique. Through ethanol desorption, 96.25% of the adsorption sites could be recovered from the regenerated activated carbon.
Adsorption isotherm and kinetics of methylene blue on activated carbon prepared from coconut husk were determined from batch tests. The effects of contact time (1-30 h), initial dye concentration (50-500 mg/l) and solution temperature (30-50 degrees C) were investigated. Equilibrium data were fitted to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The equilibrium data were best represented by Langmuir isotherm model, showing maximum monolayer adsorption capacity of 434.78 mg/g. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and was found to follow closely the pseudo-second-order kinetic model. Thermodynamic parameters such as standard enthalpy (DeltaH degrees), standard entropy (DeltaS degrees) and standard free energy (DeltaG degrees) were evaluated. The adsorption interaction was found to be exothermic in nature. Coconut husk-based activated carbon was shown to be a promising adsorbent for removal of methylene blue from aqueous solutions.
Activated carbon was prepared from coconut husk using physicochemical activation method which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO(2)) gasification. The effects of three preparation variables (CO(2) activation temperature, CO(2) activation time and KOH:char impregnation ratio) on the 2,4,6-trichlorophenol (2,4,6-TCP) uptake and activated carbon yield were investigated. Based on the central composite design, two quadratic models were developed to correlate the preparation variables to the two responses. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The activated carbon preparation conditions were optimized by maximizing both the 2,4,6-TCP uptake and activated carbon yield. The predicted 2,4,6-TCP uptake and carbon yield from the models agreed satisfactorily with the experimental values. The optimum conditions for preparing activated carbon from coconut husk for adsorption of 2,4,6-TCP were found as follow: CO(2) activation temperature of 750 degrees C, CO(2) activation time of 2.29 h and KOH:char impregnation ratio of 2.91, which resulted in 191.73 mg/g of 2,4,6-TCP uptake and 20.16 % of activated carbon yield.
An air-cathode MFC-adsorption hybrid system, made from earthen pot was designed and tested for simultaneous wastewater treatment and energy recovery. Such design had demonstrated superior characteristics of low internal resistance (29.3Ω) and favor to low-cost, efficient wastewater treatment and power generation (55mW/m(3)) with average current of 2.13±0.4mA. The performance between MFC-adsorption hybrid system was compared to the standalone adsorption system and results had demonstrated great pollutants removals of the integrated system especially for chemical oxygen demand (COD), biochemical oxygen demand (BOD3), total organic carbon (TOC), total volatile solids (TVS), ammoniacal nitrogen (NH3-N) and total nitrogen (TN) because such system combines the advantages of each individual unit. Besides the typical biological and electrochemical processes that happened in an MFC system, an additional physicochemical process from the activated carbon took place simultaneously in the MFC-adsorption hybrid system which would further improved on the wastewater quality.