Kinetics of monomer biodegradation in soil

Area of Science:

• Agricultural Science
• Polymer Science
• Environmental Science

Background:

• Conventional plastics are widely used in intensive agriculture, posing environmental challenges.
• Biodegradable plastics are being explored as sustainable alternatives.
• Understanding the biodegradation kinetics of monomers is crucial for developing effective biodegradable polyesters.

Purpose of the Study:

• To evaluate the aerobic biodegradation of ten potential monomers for biodegradable polyesters in soil.
• To determine key biodegradation parameters including solubilization and biodegradation kinetic constants, lag time, and carbon fraction.
• To assess the suitability of these monomers for developing environmentally friendly agricultural plastics.

Main Methods:

• Ten monomers (e.g., lactic acid, succinic acid, adipic acid) were tested for biodegradation.
• ASTM 5988-96 standard respirometric test was employed to measure carbon dioxide evolution over 27-45 days.
• The AQUASIM code was used to process data and estimate biodegradation parameters (K(sol), K(b), t(lag), Y).

Main Results:

• Biodegradation kinetic constants (K(sol) and K(b)) varied significantly among monomers.
• The carbon fraction biodegraded but not respired (Y) ranged from 0.32 to 0.58.
• Lag times (t(lag)) were observed for azelaic acid, 1,2-ethanediol, and terephthalic acid, ranging from 3.0 to 4.9 days.

Conclusions:

• The tested monomers exhibit varying degrees of biodegradability in soil.
• Kinetic parameters provide insights into the degradation pathways and rates of these monomers.
• Results support the potential use of these monomers in synthesizing biodegradable polyesters for agricultural applications.