Characterization of charcoal produced by different Pyrolyzing techniques

Different pyrolyzing techniques are assumed to yield products with different content and adsorption rate. This study aimed to characterize five coconut charcoal samples from different pyrolyzing techniques such as Drum Kiln, Pit Method, Top Lift Updraft Method for TLUD – Top Sample & TLUD – Bottom Sample, and Hookway Retort to determine the best production method that will yield a quality of charcoal suitable for adsorption applications. Proximate analysis and adsorption kinetic studies were done to characterize and determine the rate of adsorption. Charcoal samples were ranked based on the following criteria and weights: 70% for adsorption capacity, 20% for fixed carbon, and 10% for the volatile matter. High adsorption capacity, high fixed carbon, and low volatile matter are good charcoal qualities for adsorption. For proximate analysis, ASTM Methods (ASTM D3302, ASTM D3175-17, ASTM D3174-12, ASTM D3172-13) were used. Experimental data showed that fixed carbon content of charcoal samples from Drum Kiln, Pit Method, TLUD-Top, TLUD-Bottom, and Hookway was 54.63%, 56.84%, 64.77%, 45.85%, and 56.59% respectively; while 30.69%, 31.65%, 20.65%, 43.39%, and 24.13% respectively for the volatile matter. For adsorption kinetic studies, optimization was done using Box-Behnken design with initial concentration, adsorbent dose, and pH as factors. The Hookway sample was subjected to optimization, where its optimum conditions were used for the rest of the charcoal samples. The experimental data for the adsorption kinetic studies showed that the pseudo-second-order exhibited the best fit for all the charcoal samples. The coefficient of determination for charcoal samples from Drum Kiln, Pit Method, TLUD-Top, TLUD-Bottom, and Hookway Method are 0.9253, 0.944, 0.7267, 0.9885, and 0.9216. Applying the weights, the best charcoal sample is from Kiln, followed by Pit, TLUD-Bottom, TLUD-Top, and Hookway. Production temperature, pressure, and humidity could be employed in future studies to determine what affects the quality of charcoal during pyrolysis.