Effects of binders and reinforcers on physical and chemical properties of granular activated carbon from eucalyptus bark

Abstract

The present study reports the preparation procedure and characterization of the granular activated carbon (GAC) derived from eucalyptus bark using different types of binders and reinforcers. Firstly, eucalyptus bark was converted to powdered activated carbon (PAC) using the chemical method with H₃PO₄ as carbonizing/activating agent. The GAC was then prepared by mixing PAC with a mixture of binder to reinforcer. Four choices of binders to reinforcers were investigated in this work, i.e. CMC:kaolin, CMC:calcium carbonate, MC:kaolin and MC:calcium carbonate. The best choice among these four selected mixture was CMC:kaolin and the results illustrated that the optimal weight proportion of binder to reinforcer was 0.5:0.5, and the weight proportion of the mixture (binder:reinforcer) to PAC of 20:80. With this formula, the properties of the resulting GAC were: BET surface area 1,085 m² g⁻¹, bulk density 0.214 g cm⁻³, hardness number 75%, ash content 12.7% and pH 6.67. This condition gave the iodine and methylene blue numbers of 686 and 310 mg g⁻¹, respectively. It was observed that the adsorption capacity of the GAC product decreased with an increasing weight proportion of both binder and reinforcer to PAC. This was because the porous structure of the carbon was being filled by the presence of the binder and reinforcer. Although the final properties of the products were slightly lower than those of commercial GAC, they complied well with the national activated carbon standard (TIS.900-2004).