Utilization of Wood Flour in Fabricating Heavy Metal Cadmium Adsorbent Porous Ceramic from Water Solutions

Because of some properties such as high temperature, strength and stability, catalytic activity and strength to abrasion and corrosion, in more severe conditions, porous ceramics are preferred in comparison with porous metals, glass and polymers. The aim of this study was to investigate the performance of utilization of wood flour in fabricating porous ceramics and evaluate their mechanical properties. The performance of fabricated porous ceramics in removing cadmium as a pollutant heavy metal in water solutions was also investigated.
In this study, wood flour was prepared, in two mesh sizes: 40 and 80, from Paulownia wood shavings. Three levels of wood flour content (5, 10 and 15 wt. %) were mixed with ceramic powder and enough amount of water and then the prepared aqueous mixtures were casted into wooden molds and allowed to air-dried at room temperature for about 3 days. Then the air dried samples were put in an electrical kiln at 1100 °C for about 2 h to complete the ceramic preparation process. The most porous ceramic samples were used to examine their ability in adsorption and removing cadmium from water solutions in different conditions of pH, exposer time, temperature, cadmium concentration and adsorbent dosage.
Adding wood flour to the ceramic composition increased and decreased the final samples porosity and density, respectively. SEM micrographs indicated on formation of active carbon in the ceramic pores after pyrolysis of wood flour particles. The obtained results showed a significant improved performance of porous ceramics in cadmium adsorption from water solution, in comparison with non-porous ceramics. The results also showed that the optimum conditions for the highest level of cadmium adsorption were as follow: pH of 6, cadmium concentration of 10 mg/L, adsorbent dosage of 0.3 g, solution temperature of 35 °C and exposer time of 60 min.
In summary, this study shows that not only utilization of wood flour in fabricating porous ceramics was successful, but also due to the formation and existence of the active carbon in the pores during pyrolysis process, the fabricated porous ceramics offered a high performance in adsorption and removing of cadmium from water solutions.