Synthesis of granular activated carbon/zero valent iron composites for simultaneous adsorption/dechlorination of trichloroethylene

• Published in: Journal of hazardous materials Vol. 192; no. 2; pp. 500 - 506
• Main Authors: Tseng, Hui-Hsin, Su, Jhih-Gang, Liang, Chenju
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30.08.2011; Elsevier
• Subjects: Activated carbon; Adsorption; Applied sciences; Biological and physicochemical phenomena; Carbon - chemistry; Chemical engineering; Chlorinated solvent; Chlorine - chemistry; Dechlorination; Degradation; desorption; Exact sciences and technology; Groundwater remediation; Groundwaters; Iron; Iron - chemistry; Kinetics; Natural water pollution; nitrogen; Pollution; Rate constants; Reactive activated carbon; Reactors; Reduction; Streams; Trichloroethylene; Trichloroethylene - chemistry; Waste water treatment; Water treatment and pollution; Groundwater remediation; Reactive activated carbon; Reduction; Waste water treatment; Chlorinated solvent; Dehalogenation; Dispersant; Zerovalent metal; Composite material; Chemical reduction; Dechlorination; Activated carbon; Chlorine Organic compounds; Rate constant; Organic compounds; Ground water; Ethylene(trichloro); Desorption; Impregnation; Organic solvent; Adsorption; First order; Water pollution; Kinetics; Waste water purification
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.05.047

► The synthesis of new materials, GAC–ZVI composites, which combine the advantages of a sorption material (granular activated carbon) and a reduction material (zerovalent iron) is developed. ► The kinetics of the sorption/dechlorination of TCE in short- and long-term experiments is studied. ► Mass balance during treatment is performed. ► Characterization before and after reaction using BET, XRD, SEM/EDS, and TEM is conducted. The coupling adsorption and degradation of trichloroethylene (TCE) through dechlorination using synthetic granular activated carbon and zerovalent iron (GAC–ZVI) composites was studied. The GAC–ZVI composites were prepared from aqueous Fe 2+ solutions by impregnation with and without the use of a PEG dispersant and then heated at 105 °C or 700 °C under a stream of N 2. Pseudo-first-order rate constant data on the removal of TCE demonstrates that the adsorption kinetics of GAC is similar to those of GAC–ZVI composites. However, the usage of GAC–ZVI composites liberated a greater amount of Cl than when ZVI was used alone. The highest degree of reductive dechlorination of TCE was achieved using a GAC–ZVI700P composite (synthesized using PEG under 700 °C). A modified Langmuir–Hinshelwood rate law was employed to depict the behavior of Cl liberation. As a result, a zero-order Cl liberation reaction was observed and the desorption limited TCE degradation rate constant decreased as the composite dosage was increased. The GAC–ZVI composites can be employed as a reactive GAC that is not subject to the limitations of using GAC and ZVI separately.