Removal of Antibiotics from Water Using Functionalized Celluloses
Open Access
- Author:
- Kennedy, David
- Area of Honors:
- Chemical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Amir Sheikhi, Thesis Supervisor
Wayne Roger Curtis, Thesis Honors Advisor - Keywords:
- Antibiotics
adsorption
antibiotic removal
cellulose
nanocellulose
microcellulose
microfibrous precipitate - Abstract:
- The continual evolution of bacteria to resist treatment with antibiotics has become a looming crisis, especially amplified by the bioconcentration of antibiotics in water sources and excess antibiotics in the serum when prescribed, each leading to off-target antibiotic resistance and a possible future where society loses its greatest tool in fighting off disease. In this work, a novel adsorbent for removing especially crucial antibiotics of last resort, mainly vancomycin, but also linezolid, was been synthesized from cellulose of two different sources: Whatman filter paper and Softwood Kraft Pulp through sequential periodate oxidation to form DAMC (dialdehyde modified cellulose) fibers followed by chlorite oxidation. The microfibrous precipitate, a previously discarded byproduct in electrosterically stabilized nanocrystalline cellulose (ENCC) synthesis was synthesized and characterized through light microscopy and carboxylate content by conductometric titration (2.26 mmol/g filter paper and 4.22 mmol/g softwood Kraft pulp) before being used for removal experimentation. The carboxylated cellulose microfibers were shown to effectively bind and precipitate vancomycin from solution, with the Whatman Filter Paper product proving to be more effective than Softwood Kraft Pulp with a removal capacity of 2116 mg/g, which is nearly triple the highest reported removal capacity for any other adsorbent in the literature, compared to a still stellar 782 mg/g for the Softwood Kraft Pulp fibers. The mechanism of action was shown to be through electrostatic interaction, as proven by varying pH to show that removal only proceeded effectively in the pH range where vancomycin was protonated while the carboxylates of the filter paper microfibers were deprotonated, and the aldehyde containing fibers that get carboxylated in the microfibrous precipitate synthesis showed no removal. The presence of competing Na+ and Ca2+ cations were found to decrease removal ability incrementally with their increased concentrations and upon modelling to the Langmuir fit, it was shown that this adsorption behavior fits very well to the Langmuir monolayer isotherm. Finally, the filter paper microfibers were found to be inefficient at removing linezolid from solution, especially compared to ENCC, though neither anionic cellulosic derivative was very successful at removing the uncharged linezolid.