Related Experiment Video

Updated: Oct 1, 2025

Isolation of Native Soil Microorganisms with Potential for Breaking Down Biodegradable Plastic Mulch Films Used in Agriculture
13:38

Isolation of Native Soil Microorganisms with Potential for Breaking Down Biodegradable Plastic Mulch Films Used in Agriculture

Published on: May 10, 2013

30.8K

Free radicals accelerate in situ ageing of microplastics during sludge composting

Ruizhi Xing1, Zewei Chen1, Hanyue Sun1

  • 1Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.

Journal of Hazardous Materials
|March 3, 2022
PubMed

Insights

Free radicals generated during sludge composting accelerate microplastic (MP) degradation by promoting oxidative damage. This study highlights the crucial role of these radicals in MP aging and transformation within compost environments.

Area of Science:

  • Environmental Science
  • Microbiology
  • Chemistry

Background:

  • Microplastics (MPs) pose environmental risks, with composting being a final barrier to their release.
  • MP transformation in compost is primarily attributed to microbial action, often overlooking abiotic free radical processes.
  • The role of free radicals in MP degradation during composting requires further investigation.

Purpose of the Study:

  • To provide evidence for free radical generation during sludge composting.
  • To investigate the impact of these free radicals on microplastic oxidative degradation.
  • To elucidate the biochemical mechanisms of MP transformation in composting.

Main Methods:

  • Monitoring free radical generation (persistent free radicals and reactive oxygen species) during sludge composting.
  • Quantifying hydroxyl radical (·OH) yield and its correlation with Fe(II) concentrations.
  • Analyzing physicochemical changes in microplastics, including molecular weight and carbonyl index, after composting.

Main Results:

  • Free radicals, including persistent free radicals and reactive oxygen species, were generated during sludge composting.
  • Hydroxyl radical (·OH) yield fluctuated significantly (23.03–277.18 μmol/kg) and correlated with Fe(II) dynamics (R² = 0.926).
  • Composted MPs showed decreased molecular weight (18–27%) and increased carbonyl index (0.23–0.52), indicating oxidative aging and damage.

Conclusions:

  • Free radicals play a critical role in the oxidative degradation and aging of microplastics during sludge composting.
  • Microbially-mediated redox transformation of iron oxides on MP surfaces contributes to free radical production and MP damage.
  • This study reveals novel insights into the bio-chemical mechanisms of contaminant transformation in composting systems.
Keywords:
CompostingFree radicalsIronMicroplasticsPolystyrene

More Related Videos

Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor15:19

Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor

Published on: October 15, 2015

9.8K
Forming Micro-and Nano-Plastics from Agricultural Plastic Films for Employment in Fundamental Research Studies08:21

Forming Micro-and Nano-Plastics from Agricultural Plastic Films for Employment in Fundamental Research Studies

Published on: July 27, 2022

4.4K

Related Concept Videos

Radical Chain-Growth Polymerization: Overview01:10

Radical Chain-Growth Polymerization: Overview

Chain-growth or addition polymerization is successive addition reactions of monomers with a polymer chain. In radical chain-growth polymerization, the reaction proceeds via a free-radical intermediate. The free radical is formed from radical initiators, which spontaneously generate free radicals by homolytic fission. Organic peroxides (such as dibenzoyl peroxide, as shown in Figure 1) or azo compounds are popular radical initiators. A low concentration ratio of radical initiator to monomer is...
2.7K
Radical Autoxidation01:20

Radical Autoxidation

The oxidation of an organic compound in the presence of air or oxygen is called autoxidation. For example, cumene reacts with oxygen to form hydroperoxide. Autoxidation involves initiation, propagation, and termination steps. Many organic compounds are susceptible to autoxidation—especially ethers in the presence of oxygen, which form hydroperoxides. Even though this reaction is slow, old ether bottles contain small amounts of peroxide, which leads to laboratory explosions during ether...
2.4K
Free-Radical Chain Reaction and Polymerization of Alkenes02:35

Free-Radical Chain Reaction and Polymerization of Alkenes

The conversion of alkenes to macromolecules called polymers is a reaction of high commercial importance. The structure of the polymer is defined by a repeating unit, while the terminal groups are considered insignificant. The average degree of polymerization represents the number of repeating units in the polymer molecule and is denoted by the subscript n.
8.3K
Radical Chain-Growth Polymerization: Mechanism01:09

Radical Chain-Growth Polymerization: Mechanism

The radical chain-growth polymerization mechanism consists of three steps: initiation, propagation, and termination of polymerization. The polymerization initiates when a free radical generated from the radical initiator adds to the unsaturated bond in the monomer. The unpaired electron of the free radical and one π electron in the unsaturated bond creates a σ bond between the free radical and the monomer. As a result, the other π electron in the unsaturated bond converts this...
2.8K
Bioremediation00:46

Bioremediation

Bioremediation is the use of prokaryotes, fungi, or plants to remove pollutants from the environment. This process has been used to remove harmful toxins in groundwater as a byproduct of agricultural run-off and also to clean up oil spills.
20.7K
Spontaneous and Induced Mutations01:30

Spontaneous and Induced Mutations

Spontaneous mutations arise infrequently during DNA replication due to errors in the process. A key factor behind these errors is tautomeric shifts in nitrogenous bases, where bases transition from keto to enol forms or amino to imino forms. This shift can alter base-pairing rules, leading to mutations. Additionally, reactive oxygen species (ROS) arising from aerobic metabolism can damage DNA, resulting in depurination (loss of a purine base) or depyrimidination (loss of a pyrimidine base).
270