86 research outputs found
Assess and reduce toxic chemicals in bioplastics
No full textAssess and reduce toxic
chemicals in bioplastics
To promote a circular economy and mitigate pollution, the bioplastics industry has
begun to phase out polymers derived from
petrochemicals (1–3). This action is a positive step, but it doesn’t affect the many bioplastics on the market, which also contain
potentially harmful additives. Given that
bioplastics will likely replace polymers, it is
crucial to determine which bioplastics cause
the least harm.
Components of bioplastics can leak into
the environment. After disposal, weathering and ultraviolet degradation lead to
additional release of chemicals (4). When
determining the safety of plastic materials,
it is important to consider that such leakage
could have adverse effects on ecosystems,
wildlife, and humans (5–8).
Discarded plastics often end up in the
ocean, where chemicals leaking into the
aqueous environment are toxic to marine
life. Additives such as phthalates from
starch- and cellulose-based bioplastics can
also leak into marine environments through
wastewater and runoff from landfills. The
chemicals affect bioluminescent bacteria
and the development of sea urchin larvae
(5–7). Bio-cups, bio-polyethylene bottles, and
bioplastic supermarket bags are produced
with polylactide (PLA), a polyester derived
from renewable biomass. PLA contains
chemicals of emerging concern (CECs), such
as bisphenol A, that cause dose-dependent
increases of malformed mussel larvae (8).
More information about the CECs in bioplastics is urgently needed. No protocols are
available to characterize either the chemicals
or the leachate of chemicals from conventional and bio-based plastics (9), making
evidence-based, environmentally responsible
management impossible. Manufacturers of
plastic items and their consultants should
be required to test for molecular, organismal, and population-level effects and make
public the risks of each type of both conventional plastic and bioplastic (10). Integrated
chemical and biological approaches should
be used to assess the risks associated with
low-level exposures to CECs released by bioplastics as well as their possible combined
effects in mixtures. Assessing the toxicity of
CECs that migrate from bioplastics into the
surrounding environment could help determine how to prevent unexpected adverse
health outcomes (11).
Instead of replacing one harmful material
with another, the bioplastic industry and
researchers should work together to identify
the safest and most sustainable plastic alternatives (6). Creating and prioritizing the production of nontoxic materials with a low carbon footprint could lead to a reduced need
for landfills and less ocean plastic waste
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Biomass-Derived Activated Carbon Through Self-Activation Process
No full textSelf-activation is a process that takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon. The pyrolytic gases from the biomass contain CO2 and H2O, which can be used as activating agents. As two common methods, both of physical activation using CO2 and chemical activation using ZnCl2 introduce additional gas (CO2) or chemical (ZnCl2), in which the CO2 emission from the activation process or the zinc compound removal by acid from the follow-up process will cause environmental concerns. In comparison with these conventional activation processes, the self-activation process could avoid the cost of activating agents and is more environmentally friendly, since the exhaust gases (CO and H2) can be used as fuel or feedstock for the further synthesis in methanol production. In this research, many types of biomass were successfully converted into activated carbon through the self-activation process. An activation model was developed to describe the changes of specific surface area and pore volume during the activation. The relationships between the activating temperature, dwelling time, yield, specific surface area, and specific pore volume were detailed investigated. The highest specific surface area and pore volume of the biomass-derived activated carbon through the self-activation process were up to 2738 m2 g-1 and 2.209 cm3 g-1, respectively. Moreover, the applications of the activated carbons from the self-activation process have been studied, including lithium-ion battery (LIB) manufacturing, water cleaning, oil absorption, and electromagnetic interference (EMI) shielding
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Porositization Process of Carbon or Carbonaceous Materials
No full textPatent relating to porositized carbon processed from carbon or carbonaceous materials
Self-Activatin Process to Fabricate Activated Carbon from Kenaf
No full textSelf-activation takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon, so that a high performance activated carbon is obtained. Kenaf fiber, one type of biomass, was self-activated into activated carbon. The Brunauer–Emmett–Teller (BET) specific surface area (SABET) of non-activation and self-activation pyrolyzed at 1100°C for 2 hours were analyzed and obtained as 252 m2/g and 1,280 m2/g, respectively, with 408% difference. The results showed that the highest SABET (1,616 m2/g) was achieved when a kenaf fiber was pyrolyzed at 1,000°C for 15 hours. A linear relationship was shown between the ln(SABET) and the yield of kenaf fiber based activated carbon through the self-activation process. The study also showed that a yield of 9.0% gave the highest surface area by gram kenaf fiber (80 m2 per gram kenaf fiber), and the yields between 7.2 – 13.8% produced a surface area per gram kenaf fiber that was higher than 95% of the maximum surface area by gram kenaf fiber
Lithium battery parameter identification and SOC estimation based on dual-polarized model
No full textAn equivalent circuit model of dual polarization (DP) of lithium battery was established according to the application characteristics of lithium battery under the standby condition of 5G base station. On the basis of the model, recursive least square method with forgetting factor (RLS) was used to identify the model parameters. Finally, the Unscented Kalman filtering (UKF) was used to estimate the SOC of lithium battery in real time with the identified model parameters. The simulation and experimental results showed that the combined estimation using recursive least square method with forgetting factor (RLS) and UKF could greatly improve the estimation accuracy of lithium battery SOC, reduce the estimation error, and further verify the accuracy and effectiveness of the whole modeling
Application of Nano-SiO2 Reinforced Urea-Formaldehyde Resin and Molecular Dynamics Simulation Study
No full textNano-SiO2 is a typical modifier used for urea-formaldehyde (UF) resins to balance the reduced formaldehyde content and maintain bond strength. However, the microstructure of UF resin and the interaction between UF resin and nano-SiO2 are microscopic phenomena; it is difficult to observe and study its intrinsic mechanism in traditional experimental tests. In this work, the enhancement mechanism was explored by molecular dynamics simulations combined with an experiment of the effect of nano-SiO2 additions on UF resin. The results showed that the best performance enhancement of UF resin was achieved when the addition of nano-SiO2 was 3 wt%. The effects caused by different additions of nano-SiO2 were compared and analyzed by molecular dynamics simulations in terms of free volume fraction, the radius of gyration, and mechanical properties, and the results were in agreement with the experimental values. Meanwhile, the changes in hydrogen bonding and radial distribution functions in these systems were counted to explore the interaction between nano-SiO2 and UF resin. The properties of the UF resin were enhanced mainly through the large number of different forms of hydrogen bonds with nano-SiO2, with the strongest hydrogen bond occurring between H(SiO2)… O = (PHMU)
Sustainable Supercapacitor Electrode Based on Activated Biochar Derived from Preserved Wood Waste
No full textDue to the inherent metals (Cu, As and Cr) in preserved wood waste (CCA-treated wood waste) that pose a risk to both the environment and human health, it is crucial to dispose of CCA-treated wood properly. Carbon materials have received widespread attention for their high porosity, renewability and simplicity of fabrication. This work presents a simple and effective process for producing carbon materials from leftover CCA-treated wood (chromated copper arsenate). Utilizing CCA-treated wood derived carbon (CCA-BC) and activating it with KOH (CCA-AC), electrode materials for supercapacitor applications were created and its electrochemical characteristics were investigated. The resulting material combines the conductivity of the metal in preserved wood with the good porosity provided by carbon materials. Compared with common wood biomass, carbon (W-BC) and common wood activated carbon (W-AC), CCA-BC and CCA-AC have better electrochemical properties. After being pyrolyzed at 600 °C for two hours, CCA-AC performed optimally electrochemically in 1 M Na2SO4 electrolyte, demonstrating a 72% capacity retention rate after 2000 charge and discharge cycles and a specific capacity of 76.7 F/g. This study provides a novel approach for the manufacture of supercapacitor electrodes, which also allows preserved wood waste an environmentally nondestructive form of elimination
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