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Iron-Based Nanocomposites for Enhancing the Bioconversion of Agricultural Wastes.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Iron-Based Nanocomposites for Enhancing the Bioconversion of Agricultural Wastes./
Author:	Salehi, Bahare.
Description:	1 online resource (141 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-12, Section: B.
Contained By:	Dissertations Abstracts International85-12B.
Subject:	Nanotechnology. -
Online resource:	click for full text (PQDT)
ISBN:	9798382825618

Iron-Based Nanocomposites for Enhancing the Bioconversion of Agricultural Wastes.
Salehi, Bahare.

Iron-Based Nanocomposites for Enhancing the Bioconversion of Agricultural Wastes. - 1 online resource (141 pages)

Source: Dissertations Abstracts International, Volume: 85-12, Section: B.

Thesis (Ph.D.)--North Carolina Agricultural and Technical State University, 2024.

Includes bibliographical references

This research was to synthesize, characterize, and test a multifunctional biocomposite hydrogel for enhancing the biological conversion of agricultural wastes. The hydrogel was synthesized through chemical crosslinking of the biomaterials of carboxymethyl cellulose (CMC), arrowroot starch, and activated biochar enriched with iron nanoparticles (α-Fe2O3 and α-FeOOH). The research showed that the hydrogel prepared with the optimum formula of 1 g starch, 3 g CMC, 1.5 g activated carbon, 15 ml oxidized sucrose, and 1.5 ml glycerol in 200 ml deionized water, exhibited desirable characteristics with a high swelling ratio, BET surface area, and electrical conductivity. The hydrogel produced with the optimum formula had an iron content of 2.2 wt% and electrical conductivity of 0.73 mS/cm. It showed high hydrophilicity and could adsorb water up to 63% of its original dry mass. The decomposition of a small amount of the composite hydrogel in microbial and microalgae cultures could form iron-rich biochar particles coated with the hydrogel to serve as a conductive scaffold for attached microbial and algae growth, create a desirable microenvironment with enriched nutrients for cell and microalgae growth, and slowly release iron micronutrients needed by cells and microalgae. The hydrogel was further used to enhance microalgae cultivation, anaerobic digestion, and microbial fuel cells.It was found that the addition of the hydrogel at an optimum concentration of 2.5 g hydrogel/L in algal culture could increase the algal yield by 65.69% and the final algal cell concentration by 92.18% after 14 days. However, the addition of too much hydrogel in the algal culture decreased the yield. The study showed that the hydrogel concentration exceeding 12.5 g/L resulted in a 67.84% decrease in algal yield due to the oxidative injury caused by the additive. The hydrogel additive could significantly increase the nitrogen but decrease the carbon, hydrogen, and sulfur contents of the microalgae. The algal yield with 2.5 g/L hydrogel additive improved by 13.9% compared to the algal yield with the same amounts of non-crosslinked hydrogel ingredients.The results showed that the addition of a small amount of hydrogel in the AD could significantly increase the CH4 yield and concentration, and decrease the CO2 and H2S in the biogas. The maximum methane yield and concentration during AD of chicken litter (CL) at ~8% solid content and 55oC were 275.13 mL/ g VS and 63.3%, which were achieved by adding the hydrogel at 0.66 wt% of the slurry. The yield and concentration of methane produced by the AD with 0.66 wt% hydrogel increased by 34.5% and 7.7%, compared to the control without the hydrogel, which produced 204.49 mL/g VS methane with 58.8% CH4 in the biogas over the 21 days. The addition of 0.66 wt% and 1.32 wt% hydrogel could reduce 51.1% and 61.8% of the H2S in the biogas produced by the 21-day AD of CM, compared to the control without the hydrogel containing an average of 1,243 ppm H2S. The comparison showed that the addition of the hydrogel at the concentration of 0.66 wt% and the same amounts of non-crosslinked raw hydrogel ingredients could increase the methane yields by 34.5% and 9.1%, respectively, compared with the control.Microbial fuel cells (MFCs) provide a sustainable solution to convert organic waste into electricity using electrochemically active bacteria. The hydrogel was studied to modify the design of bioelectrodes used in MFCs for addressing the challenges of poor stability and low power density of the electrodes. The effects of various drying methods including air drying and freezing drying on the electrochemical performance of hydrogel-modified electrodes were analyzed. Air-dried hydrogel-modified electrodes were used as a control. The freeze-dried hydrogel-modified electrodes resulted in a ~ 6 times increase in capacitance (80.84 F g-1 vs. 14.42 F g-1 for air-dried one). Performance evaluations highlight the stability of activated biochar, air- and freeze-dried hydrogel electrodes over 4500 cycles.In conclusion, this research showed the multifunctional capabilities of the hydrogel. Hydrogel has potential in diverse applications, from algal cultivation and anaerobic digestion to advancing microbial fuel cell technology. The findings provide valuable insights into nuanced effects on various biological processes, paving the way for practical implementations in sustainable biotechnological applications.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798382825618Subjects--Topical Terms:

557660
Nanotechnology.
Subjects--Index Terms:

NanoparticlesIndex Terms--Genre/Form:

554714
Electronic books.

Iron-Based Nanocomposites for Enhancing the Bioconversion of Agricultural Wastes.
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