DOAJ (DOAJ: Directory of Open Access Journals) · 2019 · 12 citations · 0 references
EngineeringChemical EngineeringEnvironmental EngineeringEnvironmental RemediationSurface ScienceWastewater TreatmentAdsorption ProcessesHeavy Metal RemovalOrganic Contaminant RemediationOrganic Contaminant RemovalSurface AdsorptionWastewater CharacterizationActivated CarbonAdsorbent CapacityAdsorbent CharacterizationAdsorption Of Organic PollutantsOrganic Pollutant RemovalPhenol RemovalRemovalWastewater Treatment Processes
Phenol and Cr(VI) are two of the most common organic and heavy metal-based pollutants found in industrial \neffluents. Both pollutants pose considerable health risks if left untreated. Activated carbon adsorption is \ngenerally used for the physical removal of these types of pollutants during wastewater treatment. This work \ninvestigates the use of thermally exfoliated graphite as an alternative adsorbent material for the removal of \nphenol and Cr(VI) in wastewater. The well-developed surface pore structure and high adsorption capacities \nreported in literature make this material an ideal candidate for investigation. The effectiveness of the exfoliation \nprocess was characterised using x-ray diffraction whilst the particle morphology, surface structure and \nadsorption surface area were determined using scanning electron microscopy and Brunauer-Emmett-Teller \n(BET) specific surface area measurements. Upon expansion, the particle morphology of expandable graphite \nchanged from flakes to worm-like, accordion structures. This change was accompanied by an increase in BET \nsurface area from 2.4 to 22.4 g/m2. Batch experiments using simulated wastewater revealed that expandable \ngraphite had negligible adsorption affinity towards both pollutants. However, exfoliated graphite had adsorption \ncapacities of 0.73 mg/g and 0.55 mg/g for Cr(VI) and phenol. The equilibrium adsorption isotherms for both \npollutants were best described by the Langmuir adsorption model and had adsorption constants of 0.84 and \n0.32 L/mg for the two pollutants. The adsorption capacities obtained were much lower than those reported for \nthe same pollutants when using activated carbon as an adsorbent. This is most likely due to the high BET \nsurface areas recorded for activated carbon. Additional modification of the exfoliated graphite is required before \nsatisfactory adsorption capacities can be achieved for large-scale wastewater treatment applications.