Rinse, Repeat… Research

Same old, same new. Right now, it’s just repetition of what I’m familiar with and what I’m still unfamiliar with. I’ve got the hang of running the RO system and using the goniometer to measure contact angles, but I’m still learning how ATRP (remember atom transfer radical polymerization?) works. It’s a lot of chemistry and science at a molecular level because initiators, buffers, attachments of copolymers, etc. are involved. In case you don’t remember from my last report, it is one of the most commonly employed techniques for the development of new materials due to the ability to control molecular weight and polymer structure throughout the process.

We decided to reduce the salinity concentration of the feed water for the RO system because the first modified membrane’s permeability was negatively affected by the polydopamine phase (which acts as the initiator) and therefore it’s flux was low relative to the commercial BW30 membranes. Lowering the salinity allows us to better characterize the surface, especially since the concentration will be at a saturation index of less than one (because at an index of greater than one, crystallization is going to occur regardless of the surface chemistry of the membrane). The concentration at the membrane surface also has to be taken into account because it is always greater than the concentration of the feed. There was a reduced appearance of scaling on the membrane surface after 48 hours in the RO system, but, again, the flux was lower at the same pressures and cross flow as the commercial membranes. Just to give you an idea, the commercial membrane produced a flux of approximately 1.7 mL/min at 350 psi while it took a pressure of about 400 psi to reach the same flux with the modified membrane.

There is a lot of room for error throughout the ATRP procedure, so non-homogeneity is expected, but a lack of uniform coverage of the membrane surface with the copolymers is an issue when it comes to reducing scaling. We were measuring contact angles the other day and the first strip of the newly modified membrane was giving us very low angles with drops of water, which is exactly what we wanted because it indicates that the surface is more hydrophilic. Then, we tried another strip of a membrane from the same modified batch and the angles were almost twice as large. When the membrane was examined more closely, there was a varying level of dullness on the surface, which could be evidence that the modifications are not taking place throughout the entire surface evenly.

This week has been a race against time, with my work ending this Friday and Humberto’s conference taking place a week later. We’re hoping that by performing more ATRP on membranes and having a better handle on the process and consistency of modification, we can gather more agreeable data on the effects of ATRP on scaling. My next post will detail the end of my research here at Yale, and hopefully I’ll have conclusive results by then. Wish me luck!

Polymers and Such

Does it ever end? Research seems to be never ending, even after you publish a paper. There always seems to be something you can test more, expand further, push to no end, but I guess that’s science. How will I put an end to my research here at Yale? Two weeks left and I’m still learning so much. Not only to do with my research but life in general. My month on the East Coast has been more than rewarding and I’d like to think that I’ve grown and matured in many ways. The past two weeks have been eventful and hectic (in the best way possible). Membrane modifications coincided with travels to New York. Hours of contact measurements preceded a trip to Boston. And now we’re working on testing a modified membrane in the RO system just before I make my way to New York for the last time before my time on the East comes to a end.

The week before last was mainly filled by contact angle measurements and calculations of the interfacial energies between the gypsum crystals, water, and surface. Last week I was introduced to ATRP or atom transfer radical polymerization, which is the versatile synthetic tool we will be utilizing to modify the commercial membranes. This process enables the preparation of new (co)polymers with precisely controlled molecular weights, relatively low disparities, composition, and diverse functionalities. We worked with Chanhee, who is working on creating an omniphobic surface that is permeable to only water vapor (so cool, right?). The first step was in preparation for polymer and consisted of applying a PDA coating to the membranes in order for the desired polymers to be attached later on. Then after 20 minutes of PDA, the membrane was coated with an initiator that allows the ATRP to take place. The initiator polymerizes the surface, on which the desired zwitterionic polymers actually attach to. We allowed ATRP to take place for an hour, while Chanhee left one of his membranes for two. It is important to know that modification of the membranes varies as the amount of time for each coating varies.

The point of attaching the zwitterionic polymers or modifying the membrane at all is to make the membranes more hydrophilic. This lab is really pioneering the use of ATRP for non-biofouling purposes, so a lot of uncertainty exists with testing the modified membranes, which we will begin today. Our hopes are that a more hydrophilic surface will cause more water molecules rather than gypsum crystals to gravitate towards the surface of the membrane and attach. Just like if you want to sit in a full classroom, you would have to displace someone from their seat, if water molecules cover the entire surface then there would be no room for gypsum crystals to position themselves.

I’m learning a lot and am realizing, not only how important chemistry is, but how often unpredictable obstacles can occur in research. Recently, in a meeting, Elimelech was explaining how unexpected events can lead to schedule changes and, as result, everything ends up taking a lot longer than initially planned. (The following Tuesday, the chiller used to control the RO system temperature wasn’t running properly so we had to postpone our experiment). All of these new chemical processes and life lessons were complimented by experiences of new lifestyles and city cultures. My first trip out of New Haven was to Boston where I met up with my roommates from Rice. Then I traveled to New York the following weekend to see my best friend from high school. I must say that I do prefer New York over Boston, but the city was rich in history, which was prevalent from its charming architecture and urban design.

Another aspect of Ph.D life that I was not familiar with is conferences. There is a conference at a university in New Hampshire that Humberto is attending at the end of this month, where he will be presenting his research along with other graduate students. It’s just another aspect of being a research student, and provides him with the opportunity to share his ideas with experts in his field and receive feedback on his project. This event, however, has added an extra time constraint to his current work because he wants to be more than prepared with data and analyses for questions and considerations from his colleagues. It must be stressful preparing for a conference, but it’s reassuring to have a community of scholars to support your efforts.

These five weeks have flown by and I’m excited to see how things come to an end with regards to my research. I hope I come away with conclusive results and a wealth of knowledge. Look out for more updates on how our modified membrane compares to the commercial grade. Below are some pictures I took throughout my adventures in the big cities (includes some artwork from the MoMA).

Rachel Harrison-MoMA






Solving for the Unknown

So to start off, I have been waiting for a Yale net ID for what is going on 2 weeks now. This has severely impacted my participation in the lab because I have not yet been able to complete the lab safety training and therefore can not work in the lab independently. A certain level of bureaucracy exists that the registration form has to make its way through. As a result, I have been shadowing the (soon to be Dr.) Humberto Jaramillo during his routine tasks and experiments in the lab. To my benefit, instead of going off and doing things on my own, I have been receiving a wealth of knowledge about each step and procedure as they are performed (plus I wouldn’t say that I am completely incapacitated, but my participation has still been minimal). Thankfully, Humberto is a top notch mentor, and goes out of his way to make me feel comfortable and well informed.

The lab PI, the famed Menachem Elimelech, who happily took me under his wing this summer, has been out of town this week, but seems to be a more hands-off type of mentor to his graduate students. Last week, I attended a meeting with Humberto, Changhe (a fellow researcher with a similar research topic), and the very own Dr. Elimelech in the flesh. It consisted of Humberto detailing his current progress and future endeavors accompanied by data to support the basis of his plans. Elimelech was very direct and blunt with his opinions and directions, quickly weeding out what he deemed unnecessary and lacking quantifiable backing. He’s a busy man and there’s a certain feeling I get throughout the lab that he is pushing for as many papers to be published as quality allows. That’s not to say that he is a respectful and intellectually considerate mentor that allows his students to figure out many lessons of grad school on their own (to their advantage of course).

Furthermore, in that quick meeting, Humberto outlined some of his goals. Another part of his research involves running a reverse osmosis system using the control and modified membranes. That means that he has the system running almost 24/7 in a unit that he constructed with the help of the lab technician, Evy. Two plates sandwiching a membrane act as the center of the system. A feed source containing calcium chloride and sodium sulfate is pressurized through a pump and pushed into the bottom plate and through the membrane’s active layer. The concentrated feed is left behind while filtered water is fed through the top plate and through a flux meter where the flow (mL/min) is gauged. Ideally, we run the system until a 40% reduction in flux occurs, which takes approximately 12 hours. The first few hours of runtime is known as the induction period, which is the initial slow, steady stage of crystallization of gypsum. The remaining time consists of rapid surface crystallization on the membrane surface that inhibits the flow.

We have been running the reverse osmosis (RO) system under varying conditions, but currently, the parameters have included a temperature of about 25°C (the chiller has been broken for weeks), a pressure of between 300 and 400 psi (we want an initial flux of about 1.7 mL/min), and a feed stock with a concentration of 0.019M for both calcium chloride and sodium sulfate to give us a conductivity (slightly above saturation) of approximately 6.1 mS (microsiemen). All of these factors affect how much salt is dissolved in the solution because we don’t want bulk crystallization in the feed that could damage the pump and be confused with surface crystallization if deposited on the membrane surface. Pressure affects the flux. Intuitively, as the pressure increases, the flux increases but scaling also occurs more quickly. Pressure is also important because, on an industrial scale, higher pressures means more input energy and therefore higher operational and capital costs, so we want our modified membranes to have higher fluxes at lower pressures.

Presently, only our control commercial membranes for brackish water have been tested in the system, so the next step is to modify membranes based on results from the self-assembled monolayers (SAMs). We used a goniometer to measure the contact angles of three known liquids on our newly modified monolayers on which the acid, amino, and alcohol were grown through wetting experiments. The surfaces of the three different monolayers were tested with drops of water, glycerol, and diiodomethane. Currently, we are working on calculating the van der Waals and acid-base interaction forces for the surface using complicated derivations of Young’s equation (the complex, grad-level equation). The contact angle and the known Lifshitz-van der Waals surface tension, electron-acceptor, and electron-donor components of each liquid (two of which must be polar) can be used to determine the different surface energy components of the solid (membrane or SAM). The results from the wetting experiments will then be used to justify how the different modifications of the membrane work to reduce fouling.

We are in the stage of experimentation, which involves a lot of trial and error, especially when running the RO system under varying conditions for optimal results. Wish us luck on our endeavors as we face uncertainty head on and stay updated to learn more about our finding!


I’m Not an Imposter

The other day my mentor, Humberto, was telling me about imposter syndrome. It was first coined in 1978 by clinical psychologists and refers to “a collection of feelings of inadequacy that persist even in face of information that indicates that the opposite is true. It is experienced internally as chronic self-doubt, and feelings of intellectual fraudulence” (as defined by the Caltech Counseling Center). Researchers have divided it into three sub-categories reflective of general feelings: (1) feeling like a fake, (2) attributing success to luck, and (3) discounting success. All three of which are associated with similar symptoms including a belief that one does not deserve his or her success and a fear of being, “found out”, discovered or “unmasked”.

After doing my own research on the topic and some “soul-searching”, I realized that I, by actively deflating my ego, have subconsciously been causing myself to take on some of these symptoms. I have always preferred to be the type of person who is modest rather than overly-confident about his or her successes, but when it starts affecting my outlook on my post-graduate plans, I’d consider it an issue. Humberto was relating his own feelings of inadequacy to me when he brought up imposter syndrome. He attributed grad school and the resulting environment as the reason for a lot of the self-doubt he experiences. Being surrounded by the cream of the crop and feeling like you are expected to know things that you may not know yet is intimidating, to say the least.

“Are you considering grad school?” has been the question of the week. It’s a simple yet loaded question and being at Yale has given me some time to seriously consider the answer. It’s definitely not for everyone because it requires time, dedication, independence, and focus. Not everyone can direct that type of energy into a specific field of expertise for 5 (or more) years. Not to mention, the amount of trial and error and associated stress that begins to weigh over you may begin to compromise your initials goals and dreams. However, for me, a big aspect of my inner-contemplation with the idea, has been whether or not I want to place myself in an environment where self-doubt and fear of failure are constantly looming. You must have the ability to find value in your research and the experience as a whole. The title is one thing, but actually making a difference in your field (or even the world) is another. Currently, it’s hard to know whether or not I will feel passionately enough about a certain issue associated with the environment or the world’s resources to pursue a Ph.D researching it, but I guess a lot of what grad school is about is uncertainty.

These intellectuals are researching because they simply don’t know. They may have educated guesses or ideas about answers but they’re still uncertain. For me, uncertainty has come to define a large aspect of grad school and show me that it isn’t just about intellectual maturity, but emotional maturity. Controlling and balancing your thoughts while maintaining your focus. Finding significance in your work depends wholly on what you seek out of your research and it doesn’t have to mean saving the world. Most importantly, understanding that your path does not have to coincide with others’ and may take different twists and turns, but may still lead you to your final destination. It’s an arduous process and I hope that through the next few years I can build the knowledge, confidence, and decisiveness to figure out what next step I want to take with my life.

I dedicate this post to Humberto himself for showing me (whether he realizes it or not) that imperfections and errors will always persist in research and to stay optimistic and confident in your position and efforts that got you there. Error is not a reflection on who you are as a student, researcher, or intellectual, it’s how you approach an issue that says more about who you are as a person. Stay tuned for research updates to come and potentially more personal streams of consciousness. ;P



Redirecting My Energy

It was 3:00am and I was surprisingly awake considering how early it was. My mom shuffled out of her room, half awake, yet still loaded with questions to fill her mental checklist (typical to a worried mother, whose youngest is about to embark on a journey across the country). “3:30,” she said, “that’s when we’ll leave for the airport.” My flight was at 5:50am…Fine, I thought, better early than rushing to my gate (more to appease my worrisome mother than anything). My father, on the other hand, was savoring his last few minutes in bed and protested overruled that we leave so early. “We don’t need to leave sooner than 4,” he commanded. Overall, it was just too much discord for 3 in the morning, so, as usual, we listened to my father.

We embarked on the 30 minute drive to the airport and my mother insisted on waiting with me to check in my baggage, which resulted in us waiting in the wrong line for 15 minutes (after I urged her that we were in the wrong line more than once). So with that 15 minutes plus the additional 20 minutes of waiting in the right line, I was feeling a little stressed for time entering the TSA security line. To my relief, everything worked out, with me arriving at my terminal 1 minute before boarding. After nearly 8 hours, I landed in the tiny Tweed Airport in New Haven around 2:30 pm with 5% of battery left on my phone, which added a little excitement to my journey. I was happy to finally be able to grab an uber (before my phone died) and head to the apartment I would call home for the next 7 weeks, when I realized that I did not have my debit card. The card that contained all of my money was missing at the worst time possible. After about 15 minutes of searching, panicking, and then finally composing myself, I managed to call my mom (without my phone dying) and arrange for an uber.

Once on the streets, I noticed it was a damp and chilly day in New Haven (not the greatest first impression), but I reached the charming atmosphere of Chapel St. and entered my apartment. It was adorable with the perfect amount of old New England yet modern East Coast charm. I settled in, and, despite unpacking my things, an empty feeling began to settle in. Being in a unfamiliar place where I didn’t know anyone was lonely, especially after a long day of traveling and unanticipated obstacles. So I ended up doing what takes my mind off things the best–cook. I made a hodgepodge of what was left in the fridge from the previous tenant (to my benefit, she was very into high-quality food products). This random mixture of ingredients came to reflect my emotions the next morning. Anticipation, anxiety, excitement, and determination.

I woke up earlier than I was used to and made the 15 minute trek to the Mason Laboratory on the Yale campus. To my delight, the weather juxtaposed the dreariness of the previous day, giving me a wave of optimism as I soaked in the brisk air and sunlight. I finally reached the office of Humberto Jaramillo, room 306, with the direction of a kind, older woman who sensed my unfamiliarity with the building. After a quick, “hello” and “nice to meet you”, Humberto quickly made me feel at ease and comfortable. He took his time going through his research topic as well as taking breaks to talk about his personal life and influences for entering grad school and asking questions about my life and interests. The anxiety I had built up over the past few days had finally subdued and I was finding myself more and more intrigued by his research. I began to draw away from my own personal issues (like a lost debit card) and contemplate how living without clean water would affect my life.

Today, water quality and accessibility have come to define many major global issues. According to a review on reverse osmosis by Menachem Elimelech, presently, over one-third of the world’s population lives in water-stressed countries and by 2025, this figure is predicted to rise to nearly two-thirds. Currently, our only option is to improve the use of existing water resources and that means utilizing more efficient desalination and water reuse technologies. So, as a part of NEWT’s Thrust III team, Humberto has tasked himself with the job of reducing the deposition of gypsum on the surface of reverse osmosis membranes by modifications through polymer growth on the membrane surface itself. With me as his trusty sidekick, we will be producing self-assembled monolayers of gold-coated, silicon wafers on which three different polymers will grow–an acid (COOH), an amino (NH3), and an alcohol (OH). The contact angle of three different liquids will then be measured on the three uniquely modified surfaces and a control membrane for brackish water. These angles will then be used in very complex and graduate-level equations to solve for the surface energy of each surface.

The premise behind finding the surface energies is that the energies correlate to how likely gypsum is to crystallize on the membrane surface and cause fouling, which ultimately decreases the flux of the treatment system by reducing the flow and therefore separation of salt from water. Currently, commercial brackish water membranes have a certain surface energy that we expect to be higher than the membranes we modify. With a higher surface energy, gypsum is more likely to attach and grow into what we call rosette structures, which are reflective of surface crystallization. By lowering the surface energy, gypsum is less likely to attach to the surface and instead remain in the feed source without causing scaling. Ultimately, by reducing fouling, reverse osmosis membranes will have longer periods between cleanings (lower maintenance costs), require less energy for higher fluxes (lower capital and operational costs), and have overall longer lifespans.

I hope I covered enough background to build a basis for understanding membrane modifications. Despite how complex it can be, there is more to my research than contact angles and equations. I am slowly realizing that my time can be better spent on work that can actually impact more than just myself. I hope to touch on our other research endeavors in future posts, so stay tuned for more to come!

Out of Limbo

Being at home has felt different recently. I’ve felt like I’ve almost been in a state of limbo, like I’m just waiting for my life to pick up again after finishing sophomore year (I can only watch so much Netflix). I think Yale will be the catalyst I need to get going again. Today, I ran around Austin (my hometown) taking care of some last minute tasks (shopping) before I leave, but I think mental preparation has been the most important in getting ready. I feel like I have been mentally preparing myself the past few weeks to be on my own in New Haven with pep talks, convincing myself: I can do anything! Limitations are created by the mind! I’ve set a goal. By the end of the summer, I would like to go from amateur researcher to reverse-osmotic-semi-permeable-membrane-fouling expert. I am aware, however, that that depends wholly on how I choose to invest my time and effort.

A cultivation of knowledge

Environmental engineering has always been a major to me during my time at Rice University. I think that I have lacked experience in the field to really get a good idea of what to expect from it as a career. I have always been interested in sustainable design and renewable resources and technologies, so having the opportunity to research associated topics independently this summer is incredible. I will be working under a NEWT graduate student, named Humberto, to research better methods and technologies for desalination. That’s a very broad description of it, I know, but I hope to expound on it further throughout the next 7 weeks. I must say that the prestige associated with Yale has weighed over me the past few weeks. The anxiety and nerves from fear of not being knowledgable enough have come and passed. It was our last conference call that made me begin to believe in myself. All of the NEWT interns, including myself, presented on their research topics and Dr. Leautaud began to explain how the internship program is supposed to encourage greater exploration and foster NEWT graduate students. She continued, “I can really see it from you guys,” which made me feel confident in my current and future abilities.

My social realm

Solitude is kind of bittersweet. Sweet in that I enjoy being by myself. Bitter in that it can get lonely. Sometimes I convince myself that I have mild social anxiety when it comes to meeting and conversing with new people, but I quickly get over it once I’m out of my comfort zone. For me, a big aspect of this research opportunity is pushing my boundaries and really getting to know myself and abilities by working in an unfamiliar place. I’m excited to see how I flourish in New Haven and how much I expand my social bubble since I am the only NEWT intern traveling to Yale.

These next few weeks will be a test of knowledge and character and I am eager to detail the coming days that I hope will be filled with learning, adventures, and good food.