Technical Paper corrections/feedback

Operation: Ocean Clean-up

Graphene-based microbot’s heavy metal removal in aquatic environments.

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Clark College

Peterson

ENGL 235

Letter of Transmittal

Mr. Tobias Peterson,

Enclosed is my report, “Operation: Ocean Clean-up.” One of the struggles I faced while writing

this report was finding acceptable articles and research about graphene-based microbot. Almost

every article referred to these tiny machines with different names. Most of the research I could

conduct regarding future applications for graphene- based microbots is already in existence. In

my case, I had to think of a way to say that Initech could invest in microbots that adsorb

alternative pollutants, such as dyes, after the initial microbots that target heavy-metals. I had

plenty of time to work ahead and start the research for this report but I prioritized my other

science classes ahead of technical writing.

What I learned in response to each of the learning outcomes:

a. Locate, evaluate, and integrate credible research into a written document for a specific

purpose and work-world audience.

a.a. I learned the importance of gathering specific evidence from the text when I am

including it in a written document. For example, when I elaborate on my ideas, I need

to include a summary or quote from the original source and cite it to support my

thoughts.

b. Apply appropriate formatting and visual aids for a specific purpose and work-world

audience.

b.a. I learned the vitality of referencing your visual aids in the text. I didn’t think that was

necessary in writing because visual aids generally have a description.

c. Edit for accuracy, brevity, clarity, to write and ethical document with a specific purpose

and work-world audience.

c.a. This was the most used learning target because it will help you come off as a better

writer and won't make your audience guess your intentions. Being clear and concise

leads to less confusion. When there are less distracting words and more specific

words you are doing your job as a writer.

d. Contribute successfully to a group in the creation of work-world documents.

d.a. It’s important to stand your ground and effectively communicate with your team to

have a document that includes all its necessary pieces. Working in a group requires

putting your differences aside in order to effectively contribute your share to the

project.

I believe this class will be most helpful to me in my future studies and career because the

repetition of being concise is hard to forget. This class has made me become aware of who I am

writing to and their knowledge about my topic. I do not think about audience’s awareness about

the information I am presenting. Usually I assume someone is reading my work because they

already know what I am writing about. I think this way because I was taught to write about what

my instructors chose, therefore they had a strong background in that subject.

Each learning outcome had importance regarding the assignment it corresponded to. Every

assignment this quarter included the learning outcome to edit for brevity and to write an ethical

document. I believe this would not be an effective class if that particular learning outcome

wasn’t the primary focus. In the beginning of this quarter I learned what it meant to be a

technical writer, and the aforementioned learning outcome is a shortened version of how to be a

technical writer. Being able to integrate credible research into a written document is also very

helpful in writing the final report. Giving your audience solid facts supported by credible

research and citations makes you look better as a writer. Applying visual aids helps to ease the

wordy text in big technical reports. The only part I found helpful from the group project in

regards to the final is researching about the format of a certain style. However, even so my group

researched IEEE and I chose to use APA format.

All in all, I am glad to have completed this course and gained knowledge about the technical

writing process.

Sincerely,

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OCEAN CLEAN-UP iii

Table of Contents

Information Abstract ...................................................................................................................... ii

Introduction… ................................................................................................................................. 1

Collected Data ............................................................................................................................. 2-4

Graphene Based Microbots for Heavy Metal Removal .................................................................. 2

Manipulating Performance of Graphene-Based Microbots in Various Aquatic Conditions………3

Potential Advancements of Detoxifying Water with Microbots .................................................. 3-4

Conclusion… .................................................................................................................................. 5

Recommendation… ........................................................................................................................ 5

APA References .............................................................................................................................. 6

OCEAN CLEAN-UP iv

Information Abstract

Graphene microbots have a thin sheet of oxidized graphene wrapped around a micromotor. These

micromotors are synthesized from nickel and platinum (Vilela, 2016). Free movement with the

help of chemical reactions and magnetic forces allows these microbots to swim in an aqueous

solution and adsorb metallic ions to their graphene surface. Once saturated with adsorbents, it is

possible to remove the pollutants from the surface for safe disposal.

Graphene microbots use hydrogen peroxide to catalyze movements. Conical shape helps air

bubbles pass through swiftly. Graphene microbots are picky about their ideal environment

settings. Alkaline pH, hot temperatures, and short periods of swimming yield best results for

toxic pickup (Katuri, 2016).

In conclusion, graphene microbots are effective at cleaning water sources when conditions are

right. The impact on society will be best fit for sustaining a healthy life and not introducing

carcinogens in one’s body. Scientific Reports published a study by Li regarding functionality of

3-dimensional microbots, in which Li notes possible mass production could benefit not only city

or county water supply, but also sewage tanks and grey water. Graphene-based microbots are

worth an investment from Initech for promoting a cleaner way of living.

OCEAN CLEAN-UP 1

Introduction

A study conducted by Katuri and others for applications of nano swimmers was published in

Accounts of Chemical Research. Katuri states that graphene-oxide microbots—referred to as

graphene microbots—were first created in 2004. Their purpose is to efficiently remove potential

toxic ions from aquatic solutions. Katuri also says that gold and platinum rods were originally

placed in a solution of hydrogen peroxide and resulted in movement from chemical reactions.

After experimentation, these rods were transformed into spheres and the hydrogen peroxide

moved through the device and propelled itself. New mechanisms have been founded since

and are used in a variety of applications, such as drug delivery, biosensing and

environmental remediation.

Kar, published in Science and Technology of

Advanced Materials for reducing graphene

microbots with gold, and Vilela, published in

Nano Letters for heavy metal removal with

graphene microbots, say graphene has a two-

dimensional structure similar to that of a

honeycomb. As seen in Figure 1, these bonded

hexagons are laid flat as a sheet once the

graphene is reduced or oxidized. This sheet of

graphene is wrapped around a micro-structure

that is propelled by a tiny motor, referred to as

a microbot (Vilela, 2016).

Motors in these devices aren’t composed of what

typically comes to mind: metal parts, lubricating

fluids, valves, or shafts. Instead, these particular

micrbots are driven by a series of chemical

reactions. The graphene outer shell has properties

that attract toxic metals such as “arsenic, mercury,

cadmium, chromium, and lead.” Our bodies have a

low tolerance for these metals and they will cause

biological damage if we have high levels in our

system. Most water companies insert

fluoride in their products. Some people are outraged by this harmful metal intentionally put in

drinking water, and by using these graphene nanobots, Initech could at least cure the water for

its own employees. Contrary to removing fluoride from drinking water, graphene microbots

use hydrogen peroxide as fuel, which is not safe to drink. Heavy metals adsorb to the graphene

shell upon the microbot and is only discharged when soaked in an acidic environment (Vilela,

2016). People in control of microbots have the ability to properly dispose of heavy metal

pollutants after desorption. This is essential because otherwise the pollutants have a chance to

Figure 1. (“Structure of Graphene

Microbot,” 2016).

Shown above is the lattice of

graphene that lay over nickel and a

platinum core. As the microbot

propels, air bubbles are released

causing a shift in motion which

looks similar to “swimming”. Heavy

metal ions are green and adsorbing

to the graphene exterior as the

microbot passes by (Vilela).

OCEAN CLEAN-UP 2

infiltrate water sources again.

Water is known as a cycle. This cycle also includes water that has once been a part of or is

currently involved in wastewater treatment. Harmful toxins such as heavy metals are present

in wastewater and are not biodegradable within biological systems. This is why even low

doses cause damage to our cells (Li, 2013). Graphene microbots can be used in an industrial

setting to filter the water excreted from chemical processes and pollutants from air that

accumulate in wastewater.

I sought out this data through other established researcher’s experiments and articles. I found

journals that contained relevant information to graphene microbots and my pitch for Initech.

No reliable data was found regarding the cost of these graphene-based microbots. It was

mentioned a few times that they were “expensive”. However, in this realm I cannot guess a

monetary figure for what expensive means. During this study, I was not able to perform any of

these tests myself and was therefore unable to give my results as relevant information. Lack of

financial support, proper technology to create and control the microbots, and adequate space

for experiments lead me to rely on other’s findings regarding the adsorption power of

graphene microbots.

OCEAN CLEAN-UP 3

Collected Data

Graphene-Based Microbots for Heavy Metal Removal

These graphene microbots have three

layers as shown in Figure 2. First is

the graphene-based outer layer as

mentioned above. Nickel is deposited

in the middle, used for magnetic

remote control and removal (Vilela,

2016). Santhosh conducted a study

published in Scientific Reports for

heavy metal removal in water based

on efficiency from 1- and 2-

dimensional structures. Santhosh

mentions these magnetic properties

allow for microbot reuse (Santhosh).

The inner layer is a hollow core lined

with platinum.

Platinum chemically changes

hydrogen peroxide in the solution into

oxygen (O 2 ) and water (H

2 O) after it

passes through the core. These

products are expelled out as bubbles,

which propel the microbes (Vilela,

2016).

The hourglass tubular shape is essential to

their driving power. On top of their

specific shape, they also can only

effectively move through water if a

surfactant is present in the solution. However, research by Kar states surfactants obstruct the

interface between the metals and graphene on microbots. Katuri also mentions micromotors

break down substrates, such as hydrogen peroxide (H 2 O

2 ), into O

2 or H

2 O bubbles. Further

research will need to be conducted for this measure.

While bubbles control their mobility, the direct path cannot be predicted. Microscopic obstacles

create torque in uneven patterns of shape and speed. However, third dimension movement can be

controlled by magnetic forces—as stated above—and other methods that aren’t pertinent to

graphene-based microbots. In order to remove heavy metals from vessels of wastewater or stored

water, Initech should thoroughly check that there are no signs of organismal life present.

Figure 2. (“Lead Removal and Recovery on

Graphene Microbots,” 2016).

Lead adsorbs to the graphene outer shell. A

magnetic force controls the movement of

microbots. They produce a bubble trail as they

move. Lead is recovered when soaked in acid

(Katuri).

OCEAN CLEAN-UP 4

In the same study conducted by Katuri and others, micromotors derived from zinc or magnesium

use light or magnetic forces to enable their propulsion. Using fuel to drive these micromotors can

have toxic effects in biological systems, such as if the water were to be consumed by marine life.

Currently, they are being fueled by hydrogen peroxide H 2 O

2 , which is damaging to living cells.

This makes using micromotors in biological settings complicated. Cleaning aquatics is the goal

of heavy metal adsorption, therefore using a catalyst for microbot movement that harms the

ecosystem goes against the microbot’s purpose. Thus microbots are better suited for industrial

settings.

Manipulating Performance of Graphene-Based Microbots in Various Aquatic Conditions

Optimal swimming conditions are provided in the article by Vilela: “a concentration of 1.5% (v/

v) of H 2 O

2 and 0.1% (w/v) of sodium dodecyl sulfate (SDS),” and are used in those experiments.

Around two-hundred thousand graphene microbots were released into lead-contaminated waters

for one hour. As shown in Figure 2, 60% of lead was adsorbed by microbots in 10 minutes. Over

eighty-percent of the lead in this solution was adsorbed in 60 minutes. Longer time periods did

not show better results because an equilibrium was reached between adsorption and desorption

on the graphene exterior.

Level of Lead in Water

Lead Adsorption by Graphene Microbots

0.4

0.3

0.2

0.1

0 10 60 1440

Time (minutes)

Graphene-microbots are motile in various solutions such as water, serum, and reconstituted

blood. A delay in motion was apparent when microbots were in reconstituted blood at 25°C.

Although, when the temperature of blood was raised to its homeostatic level, the viscosity

thinned and microbot swimming improved (Katuri, 2016). Initech will not be responsible for

removing lead from blood, however accidents can occur and an untouched body of water can

become contaminated by bodily fluids or plant extracts. In this case, it’s a safety feature of

graphene- microbots to have the ability of adsorbing while in viscous liquids.

Figure 3.

Lead adsorption onto graphene microbots in a

water-mixed aqueous solution (Vilela).

A m

o u n

t o

f L

e a

d

in W

a te

r S

o lu

ti o n

(p p m

)

OCEAN CLEAN-UP 5

N a

n o

m o

le c u le

s (

g -1

)

Microbots continually react with H 2 O

2 and “use up” the available resources for their movement.

This slows down their swimming speed but looks as if the lead is holding them down. That idea is counteracted when fresh H

2 O

2 is added to their environment, as microbot speed and motility

increases (Vilela). Monitors should be assigned by Initech to check the levels of H 2 O

2 present to

ensure proper removal of heavy metals.

Potential Advancements of Detoxifying Water with Microbots

A study performed by Kar observes

the type of pollutants picked out of

water from gold-reduced graphene-

oxide microbots. These microbots are

able to pull dyes from the water with

the same adsorption powers as the

regular graphene microbots. Dyes

slip into water up to 15% annually

and are regarded as a carcinogenic

pollution (Kar, 2016).

Gold-Reduced Microbots

Regular Microbots

Adsorption of Molecules on Gold-Reduced

Graphene Microbots versus Regular Graphene Microbots

18

12

Research by Kar has mentioned gold-

reduced graphene microbots are 6

developed through a series of toxic

chemical processes. This is hazardous

to the environment—the opposite 0

point of investing in these graphene

microbots. Hence the reason why

Kar’s research found a way to safely

produce gold-reduced graphene microbots by

means of photochemical reduction.

Photochemical reduction is adding hydrogens

to an existing compound with light reactions.

Adsorption of dyes is most effective while in

an environment with pH 10, and when

0 2 4 6 8 10

Time (Minutes)

temperature is at 60°C (Kar, 2016). Figure 3 shows a representation of molecule adsorption on

regular graphene microbots versus gold-reduced graphene microbots.

In addition to the various liquids potentially expelled in a body of water, if dyes somehow

managed to find clean water sources, then use of gold-reduced graphene microbots could be

beneficial in the foreseeable future. Dyes can cause just as much harm in a biological setting as

heavy metals, as they are known to have cancerous effects. Removing dyes is as advantageous as

removing lead from water.

Figure 4.

The amount of molecules able to be absorbed

by various types of graphene microbots. The

gold-reduced microbots can adsorb more

pollutants than regular graphene microbots

(Kar).

OCEAN CLEAN-UP 6

Conclusion

Overall, in my research I found that graphene helps to remove pollutants from water, such as

dyes and lead. Microbots are tiny devices propelled by chemical reaction, producing bubbles in

an aquatic environment. The optimal “swimming” conditions for these microbots include a low

dosage of hydrogen peroxide and sodium dodecyl sulfate (Vilela, 2016). Graphene-based

microbots adsorb molecules best in one-hour periods in basic conditions and warm temperatures.

Cleansing water sources is beneficial for society because of the toxic effects pollutants pose to

living beings if water is left muddled. Microbots can release their adsorbents which allows for

proper waste disposal. Although, because of confounding information regarding surfactants,

further research will need to be conducted on whether they are helpful or destructive to the

graphene microbot’s adsorption power.

Recommendation

Yes, I believe Initech should invest in graphene-based microbots for heavy metal removal in

aquatic environments. Graphene-based microbots have evidence supporting their potential for

cleaning water from pollutants such as dyes and heavy metals like lead. Humans are destructive

living creatures and pollute enough of their everyday lives—between littering, eating an

unhealthy diet, and not washing hands, there is enough risks present. One big step to take is

target an infrastructure larger than one’s own hygiene and cleanliness. Using graphene microbots

to decrease harmful toxins within our water supply can not only benefit humans, but also the

environment and promote sustainable living.

Graphene microbots can also be used as a test for determining the amount of heavy metals

industrial companies pollute into the environment. If a certain company is over a legal limit—to

be tested and decided at a future date—they can get fined and will need to take bimonthly tests

until they no longer produce pollutants over the this limit. We can determine the amount of heavy

metals present in and industrial plant’s waste by weighing a bucket of pure distilled water with

an acidic compound alone, then deposit the heavy metals from microbots into the water, remove

the microbots, and re-weigh the bucket of water.

OCEAN CLEAN-UP 7

References

Kar, P., Sardar, S., Liu, B., Sreemany, M., Lemmens, P., Ghosh, S.... Pal, S. (July 26, 2016).

Facile synthesis of reduced graphene oxide—gold nano hybrid for potential use in

industrial waste-water treatment. Science and Technology of Advanced Materials

17(1), 375-386. http://doi.org/10.1080/14686996.2016.1201413

Kauri, J., Ma, X., Stanton, M., Sánchez, S. (November 3, 2016). Designing Micro- and

Nanoswimmers for Specific Applications. Accounts of Chemical Research 50(1), 2-11.

http://doi.org/10.1021/acs.accounts.6b00386

“Lead Removal and Recovery on Graphene Microbots,” 2016. Accessed from: http://doi.org/

10.1021/acs.accounts.6b00386

Li, W., Gao, S., Wu, L., Qiu, S., Guo, Y., Geng, X., . . . Liu, L. (2013). High-Density Three-

Dimension Graphene Macroscopic Objects for High-Capacity Removal of Heavy

Metal Ions. Scientific Reports, 3(1). doi:10.1038/srep02125

Santhosh, C., Nivetha, R., Kollu, P., Srivastava, V., Sillanpää, M., Grace, A. N., & Bhatnagar,

A. (2017). Removal of cationic and anionic heavy metals from water by 1D and 2D-

carbon structures decorated with magnetic nanoparticles. Scientific Reports. doi: 7:

14107 | DOI: 10.1038/s41598-017-14461-2

“Structure of Graphene Microbot,” 2016. Accessed from: http://doi.org/10.1021/acs.nanolett.

6b00768

Vilela, D., Parmar, J., Yongfei, Z., Yanli, Z., Sánchez, S. (March 21, 2016). Graphene-

Based Microbots for Toxic Heavy Metal Removal and Recovery from Water.

Nano Letters 16(4), 2860-2866. http://doi.org/10.1021/acs.nanolett.6b00768