Water contaminated by heavy metals and plant nutrients pose a threat to human health and safety as well as the environment. The aim of this body of work is to develop, characterize, and understand the adsorption properties of green sorbents to mitigate these risks. Biochar, an adsorbent known to be both environmentally friendly and inexpensive was used. Advantages of biochar are its high surface area, easy modification, and native surface functionality. Biochars used in this study are of pecan shell or douglas fir origin, although biochar can be made from a host of waste organic materials. Pecan shell biochar was modified using a simple water soaking activation technique which is totally green and free of any harsh solvents, whereas the douglas fir biochar was modified to contain both aluminum and magnesium oxides via coprecipitation of Al and Mg sulfate salts and NaOH treatment. Chapter I provides an introduction of biochar production methods as well as a brief history of its utilization. Chapter II is a study of lead removal using biochars obtained from slow pyrolysis of dry and water soaked pecan shell biomass. In this study, water, a green and low cost reagent, was used to maximize the surface area of pecan shell biochar allowing it to adsorb more lead from aqueous solution. In this study, pecan shell biochar is analyzed using several methods including SEM, SEM-EDX, TEM, PZC, XRD, elemental analysis, and BET. Chapter III discusses the remediation of agricultural runoff water using slag and Al/ Mg modified biochar. This study characterizes both biochar and slag using various methods including SEM, SEM-EDX, TEM, PZC, XRD, elemental analysis, and BET. Chapter IV focuses phosphates in soils: An undergraduate exploration according to soil texture and amendment. The purpose of this study was to bring the cutting edge research regarding phosphate retention into the undergraduate laboratory setting.

Electrosorption-based capacitive deionization (CDI) has become a viable process for brackish water desalination and defluoridation. In this study, activated Douglas fir biochar is used as a low-cost electrode material with adsorption capacity comparable to activated carbon obtained from biomass precursors. Adding functional groups to the activated biochar enhanced salt removal capacity, providing cation and anion selectivity. The functionalized electrodes were prepared by Nafion, titanium isopropoxide, and p-phenylenediamine treatment, respectively, which introduced sulfonate, titanium dioxide and amine functional groups to the electrode surface. These modification methods are versatile and can be easily performed without sophisticated laboratory environment. Modified biochar electrodes were characterized by TEM, SEM-EDX, XRD, and XPS. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were performed to analyze the electrochemical properties of the electrodes. The salt adsorption capacity (SAC) was evaluated in a 3D-printed capacitive deionization flow cell using a chloride and fluoride ion sensor. It was found that functionalized biochar electrodes had increased SAC and charge efficiency in asymmetrical setup due to reduced co-ion effect. For example, the asymmetrical CDI cell with Nafion cathode and amine biochar anode improved NaCl removal capacity by 54% over the activated biochar symmetrical cell (identical anode and cathode), with SAC 6.01 mg NaCl/g biochar at the symmetrical cell and 9.25 mg/g for the asymmetrical cell. The charge efficiency also increased by ≈ 67% from symmetric AcB cell to asymmetric TB-05 cathode and AmB anode. This work shows that biochar can be engineered and explored broadly as an inexpensive sustainable electrode material for asymmetrical capacitive deionization.