Honors Theses


Denise Taylor, Ph.D., P.E.


Civil and Environmental Engineering and Engineering Mechanics

Publication Date


Document Type

Honors Thesis


Phosphorus contained in agricultural runoff is a major anthropogenic contributor to harmful algal blooms (HABs). Biochars are carbon-based materials produced from the pyrolysis of waste biomass that have the potential to amend soils and remediate inorganic and organic contaminants from water. Engineered biochars tailored to adsorb phosphorus from water could reduce the availability of the nutrient in agricultural runoff, reducing the size and frequency of HABs. This study observed the phosphorus adsorption properties of engineered biochars produced from two source materials, oak sawdust and cornstalk residue, and being unmodified, acid-rinsed, or loaded with magnesium prior to pyrolysis, creating acid-rinsed, unmodified, and magnesium oxide biochars. Results indicate that the unmodified biochars released phosphates into solution, hinting at a potential agricultural soil amendment similar to older slash and burn methods of burning and burying crop residue. Magnesium-loaded biochars removed ~99% of 30 mg/L phosphate with 40 mL of solution and 0.1g of biochar. Further adsorption testing of the magnesium biochars showed a maximum adsorption capacity of 174 mg phosphate/g biochar for the sawdust-based biochar and 249.6 mg phosphate/g biochar for the cornstalk-based biochar. The sawdust biochar fit well with both the Freundlich and Langmuir isotherm models, slightly favoring the Langmuir isotherm, which suggests linear monolayer adsorption as the major adsorption mechanism. The cornstalk-based biochar did not fit either isotherm model particularly well, which suggests that the cornstalk biochar is influenced by other adsorption mechanisms.

Permission Statement

This item is protected by copyright law (Title 17, U.S. Code) and may only be used for noncommercial, educational, and scholarly purposes


Undergraduate research


Civil and Environmental Engineering | Engineering | Mechanical Engineering