Dechlorination of p-chlorophenol on a Pd/Fe catalyst in a magnetically stabilized fluidized bed; Implications for sludge and liquid remediation

✍ Scribed by Lisa J. Graham; Goran Jovanovic

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 390 KB
• Volume: 54
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/s0009-2509(98)00393-5

✦ Synopsis

p-Chlorophenol is dechlorinated using a Pd/Fe bimetallic micro-size catalyst in a magnetically stabilized #uidized bed (MSFB) reactor. The catalyst is used in both powder form (d A "7 m) and entrapped in alginate beads (d @ "2.0 mm). The dechlorination reaction is performed in aqueous solution containing p-chlorophenol with and without the presence of soil particles (20% w/w). Several important operating parameters involved in this complex chemical process are studied: Pd/Fe weight ratio, the extent of palladization or the ratio of Pd (Fe) interface area to the amount of chlorine to be removed, system pH, and dissolved O . Important process resistances including formation of Fe(OH)

, Fe(OH) , and hydrogen gas bubbles, which are dependent on the mentioned operating parameters, are identi"ed for accurate representation of the overall reaction kinetics. Pseudo "rst-order kinetics (k"3.81$0.08 m/kg min) with "rst order deactivation of catalyst (k "0.12 1/min) are found to excellently represent dechlorination chemical reaction. Once the chemical kinetics were de"ned, the active Pd/Fe catalyst was entrapped in alginate beads for use in a magnetically stabilized #uidized bed. Di!usion constraints (D C "8.0;10\ m/s) through the bead material (1.5% alginate #98.5% H O) are not severe and are reported as being approximately 85}90% of the di!usivity measured in water (Shishido et al., Chem. Engng. Res. Design: Trans. Inst. Chem. Eng. 73(6), 719}725, 1995; Oyaas et al., 1995a Biotechnol. Bioengng 47, 492}500). It can be further moderated by decreasing the size of the beads and by using a nano size Pd/Fe catalyst particles . Overall, the Pd/Fe bimetallic catalyst has been shown to e!ectively dechlorinate p-chlorophenol both as a powder and entrapped in 2 mm alginate beads. Integration of the catalyst entrapped in the beads with the MSFB introduces a novel method for the treatment of di$cult to handle materials, and toxic compounds. The MSFB and alginate beads are shown to be an excellent engineering platform which can be implemented in a variety of catalytic and non-catalytic liquid-solid reaction processes.