The Positive Fate of Biochar Addition to Soil in the Degradation of PHBV-Silver Nanoparticle Composites

Abstract

The environmental contamination of soils by polymeric and nanomaterials is an increasing global concern. Polymeric composites containing silver nanoparticles (AgNP) are collectively one of the most important products of nanotechnology due to their remarkable antimicrobial activity. Biochars are a promising resource for environmental technologies for remediation of soils considering their high inorganic and organic pollutant adsorption capacity and microbial soil consortium stimulation. In this work we report, for the first time, the use of biochar material as a tool to accelerate the degradation of polyhydroxybutyrate-co-valerate (PHBV) and PHBV composites containing AgNP in a tropical soil system, under laboratory conditions. This positive effect is associated with microbial community improvement, which increased the degradation rate of the polymeric materials, as confirmed by integrated techniques for advanced materials characterization. The addition of 5–10% of sugarcane bagasse biochar into soil has increased the degradation of these polymeric materials 2 to 3 times after 30 days of soil incubation. However, the presence of silver nanoparticles in the PHBV significantly reduced the degradability potential of this nanocomposite by the soil microbial community. These results provide evidence that AgNP or Ag+ ions caused a decline in the total number of bacteria and fungi, which diminished the polymer degradation rate in soil. Finally, this work highlights the great potential of biochar resources for application in soil remediation technologies, such as polymeric (nano)­material biodegradation.

Biodegradation of PLA-PHBV Blend Films as Affected by the Incorporation of Different Phenolic Acids

“…Thus, these changes were greater when using non-volatile substances with strong antimicrobial power, such as silver species, which slowed down the degradation rate and reduced the degradation extent, suggesting a partial alteration of the compost inoculum. Other authors [ 9 , 24 ] also showed that the presence of catechin [ 9 ] or silver nanoparticles [ 24 ] in PHBV-based films promoted a remarkable delay in the biodegradation process. The possible changes in the biodegradation pattern of the films when incorporating antimicrobials depended on their release kinetics into the medium, the sensitivity of the different microorganisms responsible for the degradative process and the dose of active compounds in the films [ 23 ].…”

Silicon nanoparticles (SiNPs) in sustainable agriculture: major emphasis on the practicality, efficacy and concerns

“…The SiNPs being small, with an average diameter of approximately 7 nm and wide absorption surface area (~400 m 2 ), can easily pass through the bio-membranes compared to crystalline bulk-Si 29 . The SiNPs are being commercially synthesized from metals and metal oxides using different techniques such as sputtering, lithography, laser ablation, mechanical milling, sonication, milling, UV irradiation, sol-gel technique, reverse micro-emulsion, Stober's method, atomic condensation, spray pyrolysis, aerosol process, bio-reduction, and flame synthesis [30][31] . These techniques are categorized into two major approaches viz., top-down approach (physical method) and bottom-up approach (chemical method) [32][33] .…”

Biodegradable Antimicrobial Films for Food Packaging: Effect of Antimicrobials on Degradation

“…Costa et al [99] studied the biodegradation of PHBV with silver nanoparticles (Ag/PHBV was 0.024 wt%) in a tropical soil under laboratory conditions incorporating Biochar ® n (charcoal obtained from plant debris and waste biomass of sugarcane bagasse). Biochar ® was used as a tool to accelerate the compound degradation.…”