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The production and application of various coatings are facing a variety of sustainability issues. Recent studies have found that all paints contain semi-volatile organic compounds (SVOC) or volatile organic compounds (VOC). In addition, some paint enters the water system in the form of microplastics. This article discusses the sustainability of coatings.
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The main environmental hazard caused by paint comes from the production of its constituent materials, not the final product. The most important of these harmful components in paint is titanium dioxide (TiO2). Titanium dioxide is a widely used industrial material and is also used in sunscreens and other cosmetics.
Titanium dioxide damages the environment in many ways. Its implicit energy (all the energy required to produce it) is relatively high, between 54 and 76 MJ/kg.
Depending on the manufacturing process used to produce titanium dioxide, CO2, N2O, SO2, NOx, CH4, or various VOCs are emitted during the process. Titanium dioxide manufacturing also creates a large waste stream, such as waste acid and metal sulfates.
When the paint is dry, it will release VOC and SVOC into the atmosphere, thus harming the environment. Paint is made of solid and liquid ingredients.
When it dries, the solid pigment material combines with any additives and binder molecules to form a coating, while the liquid and solvent in the binder evaporate.
VOCs are a class of chemicals, and their use has been regulated because they can cause damage when released into the atmosphere. VOC reacts with carbon monoxide (CO) and nitrogen oxides (NOx) in sunlight to form ozone.
Unlike stratospheric ozone, which protects us from the sun’s most harmful wavelengths of light, ground-level ozone pollution is a problem to avoid. The ozone near the surface is an important factor leading to poor local air quality.
Ground-level ozone makes breathing difficult, especially on hot sunny days when the pollution is the most serious. People with respiratory diseases such as asthma are particularly affected, as are the elderly and children.
Fragile vegetation and protected ecosystems, such as parks, wildlife sanctuaries and wilderness areas, are also negatively affected by ground-level ozone pollution.
Paints usually contain plastics such as polyurethane, polyester, polyacrylate, polystyrene, alkyl, and epoxy. Therefore, they may cause a growing problem of microplastic pollution in our waterways and oceans.
This happens when the paint peels and falls off. Dry, peeling paint chips decompose in the weather but will not decompose. They are eventually washed into sewers and waterways, and finally into the ocean in the form of microplastic pollution.
Paint used mainly outdoors is an important source of microplastic pollution.
Photo Credit: MikeDotta/Shutterstock.com
The culprit is the paint used on the exterior of ships and marine infrastructure, although paint on the exterior of buildings and other outdoor structures can also cause microplastic problems.
The materials commonly used in coatings have been found to be harmful to human health and the health of the earth.
Lead used to be a common ingredient in paint, but due to the risk of lead poisoning, the use of lead has been banned for decades.
However, the ingredients in modern coatings have also been found to be harmful to human health. Propane sulfone is a widely used ingredient in paints, but it is also a known carcinogen that can increase the risk of cancer through exposure.
In addition to skin contact, toxic chemicals in paint can also enter the human body through the respiratory system.
Due to government regulations and consumer pressure, many coatings are now advertised as low or no VOC, organic, natural, or generally better for the environment. After inspection, the promise of these coatings is often not fulfilled.
Real Milk Paint, a paint manufacturer in the United States, sells various paints and coloring products made of casein (the protein in milk), lime calcium, unspecified pigment colors and unspecified plant-based fillers.
Another paint supplier, Anna Sova, sells 96% of a series of paints made up of what the company calls food ingredients, and the remaining 4% is made up of other unspecified ingredients.
Both products are sold as sustainable alternatives to traditional coatings.
However, when milk is sold as food, it contains 3.2 MJ/l of energy. Extracting casein from milk is a further manufacturing process that includes its own environmental footprint.
Regardless of that additional step, 1 liter (908.5 grams) of milk contains only about 31 grams of casein, so the intrinsic energy of casein is at least 93.8 MJ/kg. This is worse than titanium dioxide, up to 76 MJ/kg.
Some coatings are sold with sustainability as the goal, but the final performance is not much better than traditional coatings. Recent studies have found that in order to avoid solvent classification, all paints studied contain at least semi-volatile organic compounds (SVOC).
Researchers were unable to confirm the manufacturer's claim that the VOC and even SVOC levels emitted by these coatings are very low or negligible, so ventilation is not required after use.
After all, the best way to reduce the environmental impact of paint is to stop using as much paint as possible. Painting correctly, using high-quality paints that last longer, and not painting where it is unnecessary all contribute to the sustainability of decorative and architectural applications.
In the case of microplastic pollution, more research is needed to find biodegradable coatings that can withstand the pressure of the outdoor environment, especially in industrial and marine applications.
Gaylarde, C., JAB Neto and EM da Fonseca (2021). "Paint Fragments As Contaminated Microplastics: A Brief Review." Marine Pollution Bulletin. [Online] https://doi.org/10.1016/j.marpolbul.2020.111847.
Patil, S., SS Hosapete, S. Irkal, and S. Rajput (2019). Analysis of casein in different milk samples. IOSR Journal of Applied Chemistry. https://doi.org/10.9790/5736-1207012325.
Porwall, T. (2015). The harmful effects of paint pollution on the environment. International Research Journal-GRANTHAALAYAH. https://doi.org/10.29121/granthaalayah.v3.i9SE.2015.3204.
Salmoral, G. and X. Yan (2018). "Food-Energy-Water Connection: Life Cycle Analysis of Virtual Water and Implied Energy in Food Consumption in Tamar Valley, UK." Resources, Protection and Recycling. [Online] https://doi.org/10.1016/j.resconrec.2018.01.018.
Schieweck, A. and Bock, M. (2015). "Emissions of low-VOC and zero-VOC coatings-a valuable alternative to traditional formulations, which can also be used in sensitive environments." Architecture and Environment. [Online] https://doi.org/10.1016/j.buildenv.2014.12.001.
Disclaimer: The views expressed here are those of the author in a personal capacity, and do not necessarily represent the views of the owner and operator of this website, AZoM.com Limited T/A AZoNetwork. This disclaimer forms part of the terms and conditions of use of this website.
Ben Pilkington is a freelance writer interested in society and technology. He likes to understand how the latest scientific developments affect us and imagine what might happen in the future. Since completing his postgraduate studies at Oxford University in 2016, Ben has reported on the development of computer software, the UK technology industry, digital rights and privacy, industrial automation, Internet of Things, artificial intelligence, additive manufacturing, sustainability and clean technology.
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