The Pacific Index

Going green with a new kind of grass

Zach Rousslang

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Are you familiar with breast implants? What about cell phones? How about computers, solar panels, or even your nearest night light? If so then we have a common friend, or should I say two? All of the aforementioned items are engineered using a common chemical element, silicon. Silicon is one of the most versatile and abundant elements in today’s world. One of the most common derivatives is silicon dioxide, known as silica, which has applications in chemistry, biology, medicine, and semiconductor technology, as well as in both the food and space industry. Since there are so many applications for silicon compounds, it is important to master efficient techniques for obtaining and isolating this vital resource.

Going green is a recent phrase with which most Americans are familiar. It emphasizes the utilization of renewable resources while simultaneously minimizing environmental pollution and other harmful byproducts. It’s everywhere: on the side of recycled grocery bags, on water bottles, light bulbs; even modern bathroom facilities are engineered to reduce water usage. Greener is officially better. If we all want to contribute to this recent movement, then there is an extremely sustainable and under-utilized method for obtaining this “jack of all trades” silica.

Many land plants use biosilica as a protective skeleton, which enhances photosynthesis, disease resistance, insulation, and protects against heavy metal ions. One such plant that utilizes this biosilica protective shell is a member of the grass genus Zizania, i.e. rice. Rice is an important natural resource serving as a staple food source for a significant portion of the world’s population, and 20 percent of its crude mass is from the husk (portion containing silica). Approximately 500 million tons of rice are produced each year, which equates to nearly 100 million tons of rice husk byproduct. Through a series of chemical processes, it is possible to obtain high purity silica from this “waste like” husk byproduct, which equates to rice serving as a significant renewable source of this handy compound.

This chemical process can be broken down into three relatively simple steps: purification, thermal decomposition, and isolation. First, the crude rice husks can be treated with acidic solutions to remove some impurities. Second, the acid treated product from step one is exposed to high temperatures, causing combustion of the husk into a fine silica based powder. Not only does this combustion produce silica, but the thermal energy created can help drive other parts of the process. This powder is then treated and manipulated to further increase overall purity and yield.

Once silica has been synthesized and purified, the possibilities are nearly endless. The windows in your car, house, even in our school library are composed of approximately 75 percent silica. If you’re stuck in the Stone Age, and have no idea what glass is, then maybe you’ll appreciate the fact that the very ink you’re reading right now could contain silica. If that’s not enough, Innovalight, one of the world’s leaders in innovative renewable energy technology has developed a silicon-based ink, which is used for solar panels and efficient light harvesting. Innovalight’s successful conversion of solar energy into reusable energy using this ink is notably cost effective, and has received much praise from their competitors.

The other day, hidden in an isolated recess of the Pacific library, as I began reading a fresh page of my “green” chemistry book, I was alarmed by a deafening noise that only grew louder as I got further engrossed into my assigned reading. To my utter dismay, the noise suddenly stopped and anchored itself not five feet from me, right behind the adjacent cubicle. After my eardrums had recovered, I was finally able to decipher the noise and realized it was a hit single from Justin Bieber’s most recent album blaring from the stranger’s iPod, (maybe we’ll get lucky and it’ll be Bieber’s last before puberty kicks in).

As if some divine power had willed the meeting, I decided to pack up my stuff and leave the noise pollution behind. On my way out, I was desperate to clear my mind of the previous events and decided to count the number of “green” items I ran across.  Surprisingly my final tally ended at 57 before I reached my car.     Pacific emphasizes the communal effort of “going green,” but if we really want to make a difference, maybe we should start reducing all types of pollution. Rice husk is a wasteful byproduct that can be easily converted to a vital resource through a renewable process.

Regardless of how you decide to “go green,” contributing is always appreciated. Whether it’s by petitioning Aramark for rice husks to donate to your local chemist, turning down your music, or maybe even just turning the lights off while leaving a room, try to make a difference. If not for yourself, do it for me, for your neighbors, and for Mother Earth.

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