자료유형  

 학위논문

Control Number  

0016932920

International Standard Book Number  

9798379866228

Dewey Decimal Classification Number  

540

Main Entry-Personal Name  

Kasera, Nitesh Kumar.

Publication, Distribution, etc. (Imprint  

[S.l.] : North Carolina State University., 2022

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2022

Physical Description  

1 online resource(265 p.)

General Note  

Source: Dissertations Abstracts International, Volume: 85-01, Section: B.

General Note  

Advisor: Hall, Steven G.;Kolar, Praveen.

Dissertation Note  

Thesis (Ph.D.)--North Carolina State University, 2022.

Restrictions on Access Note  

This item must not be sold to any third party vendors.

Summary, Etc.  

요약The goal of this research was to study surface modification on the physicochemical properties of biochar. The objectives were to 1) explore the contrasting properties of biochar after nitrogen and oxygen treatment via different chemicals, 2) investigate the nitrate adsorption mechanism by modified biochars, and 3) get theoretical insight into the interaction between engineered biochar and nitrate through computational calculations. The research was carried out in three phases. In each phase, pine bark was used as the feedstock material to prepare biochar.In the first phase, pine bark-derived biochar was subjected to modification by melamine, urea, ammonium chloride, and ammonium nitrate to prepare nitrogen-doped biochar. The effect of chemical modification on the extent of N-doping and surface properties was evaluated. The elemental analysis suggested that melamine-modified biochar samples had 4.75% nitrogen, higher than nitrogen in other modified biochar. X-ray photoelectron spectra showed that Ndoped samples' surface nitrogen content increased to 8.3%, 3.9%, 2.3%, and 2.9% for melamine, ammonium chloride, ammonium nitrate, and urea, respectively. X-ray photoelectron spectroscopy results also revealed that among the nitrogen fractions in the N-doped biochars, melamine-modified biochar has the highest percentage of pyrrolic and pyridinic nitrogen (35.2% and 36.8%, respectively) compared to others. Urea-modified biochar had the highest percentage of graphitic nitrogen (26.6%).In the second phase, effects of biochar surface modification by oxidizing chemicals on biochar properties were investigated. Pine bark biochar was modified with sulfuric acid, nitric acid, hydrogen peroxide, ozone, and ammonium persulfate. The resulting biochars' pH, pH at the point of zero charges, and concentration of acidic and basic sites were determined using laboratory experimentation and chemical compositions were determined instrumentally. X-ray photoelectron spectra showed that oxygen content increased to 44.5%, 42.2%, 33.8%, 30.5%, and 14.6% from 13.4% for sulfuric acid, ozone, nitric acid, hydrogen peroxide, and ammonium persulfate, respectively. The pH at the point of zero charges was negatively correlated with the difference in concentration of acidic and basic sites in biochar samples, as well as the summation of peak components representing C=O double bonds and carboxylic groups.In the third phase, feasibility of chemically modified pine bark biochar's nitrate adsorption ability was evaluated. Pine bark biochar was modified with either urea or melamine and sulfuric acid to remove nitrate from an aqueous solution. Biochars were characterized as previous phases. The equilibrium adsorption data were fitted to the Langmuir and Freundlich isotherm models. The kinetic data were fitted to different kinetic models. The adsorption data fitted well with the Langmuir and pseudo-first order models. The maximum nitrate adsorption capacity was found to be 1.548 mg-1 . Mass transfer studies were conducted to identify the rate-limiting step, values of the external mass transfer coefficient, and diffusion coefficient in the nitrate adsorption process by the modified biochars. The Biot number obtained from the mass transfer studies indicated that the adsorption was controlled by film diffusion. DFT-based quantum chemical calculations were performed to gain insights into nitrate adsorption characteristics by biochar.

Subject Added Entry-Topical Term  

Nitrates.

Subject Added Entry-Topical Term  

Pollutants.

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Agricultural production.

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Lignin.

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Adsorbents.

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Water treatment.

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Nuclear magnetic resonance--NMR.

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High temperature.

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Adsorption.

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Crop residues.

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Biomass.

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Potassium.

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Outdoor air quality.

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Activated carbon.

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Scanning electron microscopy.

Subject Added Entry-Topical Term  

Agricultural pollution.

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Nitrogen.

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Raw materials.

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Environmental conditions.

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Surface chemistry.

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Cellulose.

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Heavy metals.

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Kinetics.

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Agriculture.

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Atmospheric sciences.

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Chemistry.

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Environmental engineering.

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High temperature physics.

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Materials science.

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Medical imaging.

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Physics.

Subject Added Entry-Topical Term  

Thermodynamics.

Added Entry-Corporate Name  

North Carolina State University.

Host Item Entry  

Dissertations Abstracts International. 85-01B.

Host Item Entry  

Dissertation Abstract International

Electronic Location and Access  

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Control Number  

joongbu:641746