Chemical Modifications of Hollow Silica Microspheres for the Removal of Organic Pollutants in Simulated Wastewater

Handle URI:
http://hdl.handle.net/10754/623473
Title:
Chemical Modifications of Hollow Silica Microspheres for the Removal of Organic Pollutants in Simulated Wastewater
Authors:
Torano, Aniela Zarzar ( 0000-0001-7793-1047 )
Abstract:
Aqueous industrial effluents containing organic pollutants, such as textile dyes and crude oil, represent environmental and human health concerns due to their toxicity and possible carcinogenic effects. Adsorption is the most promising wastewater treatment method due to its efficiency, ease of operation, and low cost. However, currently used adsorbents have either high regeneration costs or low adsorption capacities. In this work, new organic/inorganic hybrids based on hollow silica microspheres were successfully synthesized, and their ability to remove Methylene Blue from wastewater and crude oil from simulated produced water was evaluated. By employing four different silanes, namely triethoxy (octyl) silane, triethoxy (dodecyl) silane, trichloro (octadecyl) silane, and triethoxy (pentafluorophenyl) silane, hydro and fluorocarbons were grafted onto the surface of commercially available silica microspheres. These silica derivatives were tested as adsorbents by exposing them to Methylene Blue aqueous solutions and synthetic produced water. Absorbance and oil concentration were measured via a UV/Vis Spectrophotometer and an HD-1000 Oil-in-Water Analyzer respectively. Methylene Blue uptake experiments showed that increasing the adsorbent dosage and decreasing initial dye concentration might increase adsorption percentage. On the other hand, adsorption capacities were improved with lower adsorbent dosages and higher initial dye concentrations. Varying the initial solution pH, from pH 5 to pH 9, and increasing ionic strength did not seem to have a significant impact on the extent of adsorption of Methylene Blue. Overall, the silica derivative containing aromatic functional groups, Caro, was proven to be the most effective adsorbent due to the presence of π-π and cation-π interactions in addition to the van der Waals and hydrophobic interactions occurring with all four adsorbents. Although the Langmuir Model did not accurately represent the equilibrium data, it produced consistent maximum adsorption values and adsorption equilibrium constants. Preliminary experiments demonstrated the potential to recover and reuse the silica microspheres by washing with NaOH and organic solvents. The preferential adsorption of oil micro-droplets onto the surface of functionalized hollow silica microspheres was evidenced. However, preparing synthetic produced water that was stable enough to carry out kinetics experiments remained a challenge.
Advisors:
Mishra, Himanshu ( 0000-0001-8759-7812 )
Committee Member:
Pinnau, Ingo ( 0000-0003-3040-9088 ) ; Peinemann, Klaus-Viktor ( 0000-0003-0309-9598 )
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Chemical and Biological Engineering
Issue Date:
May-2017
Type:
Thesis
Appears in Collections:
Theses

Full metadata record

DC FieldValue Language
dc.contributor.advisorMishra, Himanshuen
dc.contributor.authorTorano, Aniela Zarzaren
dc.date.accessioned2017-05-11T11:43:11Z-
dc.date.available2017-05-11T11:43:11Z-
dc.date.issued2017-05-
dc.identifier.urihttp://hdl.handle.net/10754/623473-
dc.description.abstractAqueous industrial effluents containing organic pollutants, such as textile dyes and crude oil, represent environmental and human health concerns due to their toxicity and possible carcinogenic effects. Adsorption is the most promising wastewater treatment method due to its efficiency, ease of operation, and low cost. However, currently used adsorbents have either high regeneration costs or low adsorption capacities. In this work, new organic/inorganic hybrids based on hollow silica microspheres were successfully synthesized, and their ability to remove Methylene Blue from wastewater and crude oil from simulated produced water was evaluated. By employing four different silanes, namely triethoxy (octyl) silane, triethoxy (dodecyl) silane, trichloro (octadecyl) silane, and triethoxy (pentafluorophenyl) silane, hydro and fluorocarbons were grafted onto the surface of commercially available silica microspheres. These silica derivatives were tested as adsorbents by exposing them to Methylene Blue aqueous solutions and synthetic produced water. Absorbance and oil concentration were measured via a UV/Vis Spectrophotometer and an HD-1000 Oil-in-Water Analyzer respectively. Methylene Blue uptake experiments showed that increasing the adsorbent dosage and decreasing initial dye concentration might increase adsorption percentage. On the other hand, adsorption capacities were improved with lower adsorbent dosages and higher initial dye concentrations. Varying the initial solution pH, from pH 5 to pH 9, and increasing ionic strength did not seem to have a significant impact on the extent of adsorption of Methylene Blue. Overall, the silica derivative containing aromatic functional groups, Caro, was proven to be the most effective adsorbent due to the presence of π-π and cation-π interactions in addition to the van der Waals and hydrophobic interactions occurring with all four adsorbents. Although the Langmuir Model did not accurately represent the equilibrium data, it produced consistent maximum adsorption values and adsorption equilibrium constants. Preliminary experiments demonstrated the potential to recover and reuse the silica microspheres by washing with NaOH and organic solvents. The preferential adsorption of oil micro-droplets onto the surface of functionalized hollow silica microspheres was evidenced. However, preparing synthetic produced water that was stable enough to carry out kinetics experiments remained a challenge.en
dc.language.isoenen
dc.subjectAdsorptionen
dc.subjectSilica microspheresen
dc.subjectWastewateren
dc.subjectMethylene blueen
dc.subjectProduced wateren
dc.titleChemical Modifications of Hollow Silica Microspheres for the Removal of Organic Pollutants in Simulated Wastewateren
dc.typeThesisen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberPinnau, Ingoen
dc.contributor.committeememberPeinemann, Klaus-Viktoren
thesis.degree.disciplineChemical and Biological Engineeringen
thesis.degree.nameMaster of Scienceen
dc.person.id142816en
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