Amandaburns08

Four green, black, red and blue Bic Cristal pens and four additional caps. (Carlos Delgado; CC-BY-SA)

I am a student at Louisiana State University.

Disposal of Pens and How it Affects the Environment

Stained Earth is a study on the life-cycle of the average disposable pen. It addresses topics such as manufacturing plastics and other materials in a particular pen, the quantities on an average university campus, current disposal methods, and potential improvements in the disposal process. Although several compounds are required to manufacture a pen, this article just focuses on the plastics associated with them- polyethylene and polystyrene. Due to the use of plastic in various other products, this article could be related to other disposables containing polyethylene, polystyrene, and by association all other plastics.

Birth of an idea

When looking at potential research projects, I had a difficult time finding an environmental issue that could be explained through chemistry, not just biology. Because I am a student at Louisiana State University, I decided to choose a project that my professors and peers could relate to, at this point in our lives. Pens are essential in our lives and this project will prove this statement and provide facts about the impact plastic pens have on our environment when being disposed of. With this being said, I am very passionate about this research project and I am eager to find new ways of eliminating this issue from our environment. My contribution will be new to the wiki world. As far as I’ve seen, no one has talked about this particular issue. I used Google Scholar and LSU Libraries for my background research and the references are listed at the bottom of the page.

General facts

There is no way to determine the amount of pens the world disposes of, but it is possible to estimate. First, let's estimate the amount of pens disposed of at LSU per student, per semester. There are ~30,000 students at LSU. Unfortunately, there is no way to determine the amount of pens owned by every person on campus (i.e. professors, workers, students, etc.). So I will safely assume that every student has about five pens. This takes into account of the students who use computers and pencils as alternatives and for the people who own 50+ pens (like myself). This totals to 150,000 pens disposed of every semester- just at LSU. This is not accounting for every plastic object made in the entire world, just everyday pens at this university, only used by students. The number for everything made of plastic in the world is exponentially higher than this number. In 2015, over 297.5 million tons of plastic was distributed in the world. China takes the largest percentage, followed by Europe. This is a major issue for our environment and we need to look into alternative methods now.

Types of Plastics and Disposal Methods

There are seven main plastics that are used all around the world. They are:

1. Polyethylene terephthalate (PETE)
2. High density polyethylene (HDPE)
3. Polyvinyl chloride (PVC)
4. Low density polyethylene (LDPE)
5. Polypropylene (PP)
6. Polystyrene (PS)
7. Other (O)

The respective Wikipedia pages are linked to each. Each page can tell you the chemical formula, structure, and what each is used for in our society. Not all of these plastics can be used in a ballpoint pen as some are brittle and will break easily. Ohio State University did research on Bic Cristal pens and found that the plastic used is polystyrene. Polystyrene is cheap and clear so the user can see how much ink is left in the pen.

So the main focus on this project is polyethylene and polystyrene.

There are three possible ways to dispose of plastics:

• Recycling
• Incineration
• Landfills

All of these methods have pros and cons to them and we will go over each.

Recycling

Recycling would be the most environmentally-friendly disposal method of them all because it eliminates plastics in landfills and incineration processes. Each type of plastic has a number associated with it (1-7). When looking at plastic packaging (i.e. water bottles, bags, etc.) there is a recycle symbol and a number next to it. This number corresponds to the type of plastic the item contains. Numbers 1 and 2 are recyclable. 3 through 7 are not due to additives and ability to withstand the recycling process. Unfortunately, some of the plastics that users throw in recycling bins are actually not recyclable and have to be incinerated or discarded in a landfill.

Landfills

When in a landfill, the plastics that are biodegradable take a while to decompose. When they do, they emit harsh chemicals into the atmosphere. Also, the plastics leave organic pollutants in the soil when they decompose. In the figure of reference 8 is the mechanism of polyethylene decomposing in soil. the alkane chain gets converted into a keto chain. Then, and ether, and eventually a carboxylic acid. Eventually, and alkene chain is emitted from the degradation.

When polyethylene and polystyrene are left in marshes to decompose instead of in landfills, the process happens very quickly due to the biotic and abiotic factors. But there are still harmful chemicals that could be released during this process.

Incineration

Incineration is the process of burning waste. It is the most harmful way of disposal of pens. When polyethylene and polystyrene are burned, carbon dioxide is formed. Also as a side reaction, carbon monoxide may be formed.

Polyethylene

${\textstyle (CH_{2}CH_{2})_{n}+3O_{2}\longrightarrow 2CO_{2}+2H_{2}O}$

$(CH_{2}CH_{2})_{n}+2O_{2}\longrightarrow 2CO+2H_{2}O$

Polystyrene

$(CH_{2}CH_{2})_{n}+10O_{2}\longrightarrow 2CO_{2}+2H_{2}O$

$(C_{8}H_{8})_{n}+6O_{2}\longrightarrow 8CO+4H_{2}O$

Carbon dioxide is a harmful greenhouse gas. Greenhouse gases are molecules that trap in heat in our atmosphere. This is the cause of global warming. Carbon monoxide is a weak greenhouse gas only because it doesn't affect our environment directly. It contributes to the concentration of methane in the atmosphere as shown in the next section.

Ozone Depletion

Carbon monoxide:

$CO+\bullet OH\longrightarrow \bullet HOCO$

$\bullet HOCO+O_{2}\longrightarrow CO_{2}+\bullet OOH$

Methane:

$CH_{4}+\bullet OH\longrightarrow \bullet CH_{3}+H_{2}O$

These are the reactions of carbon monoxide and methane reacting with hydroxyl radicals. In the first reaction scheme, carbon monoxide reacts with the hydroxyl radical and, eventually, forms carbon dioxide. The second reaction scheme shows methane reacting with the hydroxyl radical to form a methyl radical, which is less harmful than methane. If there is carbon monoxide present, the hydroxyl radical will want to react with the carbon monoxide more than the methane. This renders the concentration of methane to be higher. Methane is an even stronger greenhouse gas than carbon dioxide in that it causes ozone depletion.

Ozone depletion since 1984

1. $CH_{4}O+O\longrightarrow CH_{4}+O_{2}$
2. $CH_{4}+O_{3}\longrightarrow CH_{4}O+O_{2}$

Net: $O+O_{3}\longrightarrow 2O_{2}$

This shows the breakdown of ozone by methane. As shown, none of the methane is used to break ozone down. This is a serious problem because ozone provides a protective layer between the Earth and the sun. If ozone isn't present, UV rays will enter the atmosphere and cause global warming. Overall, this is a global issue and we can start the road to recovery one step at a time- starting with pens!

Alternate ideas

We can start making pens out of a recyclable or biodegradable material. I wasn’t aware of this before the project, but they make pens made from recycled water bottles! And they’re not that expensive. 86% of the pen is made from recycled material.I haven’t been able to find anything about what kind of plastic is in it, but this is a start.There are also pens made out of wood, but there is still some plastic inside (i.e. ink holder inside of the pen, etc.) Also, pencils are a great substitution for plastic pens. It gets the job done. Pencils are made of wood, which is a lot friendlier to the environment. Unfortunately, people prefer pens due to various reasons like speed and comfort. Finally, we go back to using quills and ink bottles. This is the least-likely alternative method but it is better than what we are doing right now.

Conclusion

So I have gone over the basic chemistry of the degradation of plastic and how it hurts our environment. Hopefully this is a wake-up call for those of us who overlooked the importance of how simple items, like ballpoint pens, have severely damaged our ozone. Also, I have proposed alternative methods that will help decrease the amount of pens that end up in landfills and incineration processes all over the planet. This is a small change that can make a big impact and decrease ozone depletion.