Andrea Naranjo-Soledad, Energy Technologies Area, worked on two projects in the summer of 2020 as a Bridge Fellow at Berkeley Lab. One focused on creating a batch process system to produce disinfectant for use against COVID-19 in developing countries. The second project focused on removing hexavalent chromium — a known carcinogen — from contaminated groundwater. She is a Ph.D. student in the Civil and Environmental Engineering Department at Berkeley. Here is her report on her work.
My first project focuses on the development of a small 15 Liter batch process system for the production of a disinfectant solution, based on the well known Chlor-Alkali process, with a focus to drive the same chemistry using only items accessible to low-income communities. It would provide help to low-income communities to reduce the spread of COVID-19.
These communities have nothing but soap and water to disinfect surfaces that may be contaminated with COVID-19 virus particles. With support from Dr. Gadgil and his doctoral students, we first determined if our procedure meets an unmet and urgent need in the developing countries. For this, we created a network of 14 different collaborators in nine different countries, starting with the U.S. territory of Puerto Rico, Mexico, El Salvador, Colombia, Nigeria, South Africa, Uganda, India, and the Philippines.
Once I was granted access to Dr. Gadgil’s laboratory on-campus, his doctoral students and I studied the dependence of system performance on its design parameters, such as the current density. In the next few weeks, we hope to send the finalized parameters of the process to our 14 collaborators so that they can replicate the system on their own, and would provide technical support within their own countries to spread this design widely, to slow down the spread of COVID-19.
The second project involves understanding the scientific theory and identifying the potential for the development of a novel and effective technology for the removal of hexavalent chromium (Cr(VI)) — a known carcinogen — from contaminated groundwater. The scientific approach relies on Iron Electrocoagulation (Fe-EC) for the production of green rust (GR), which can reduce Cr(VI) to Cr(III) and remove it by precipitation. For this, I studied the published scientific literature to understand the optimal conditions (e.g., pH, the initial level of dissolved oxygen, and current density during Fe-EC) that would be suitable for the production of GR and removal of Cr(VI). Additionally, I used the Groundwater Ambient Monitoring and Assessment (GAMA) program of the State of California to define a “typical” composition of California groundwater containing Cr(VI) concentrations above 20 μg/L, for carrying out experiments with this synthetic groundwater in the lab. I have also reviewed the published literature to understand how the composition of the synthetic groundwater affects the resulting composition of GR, and thus affects the rate of removal of Cr(VI). Finally, I will also study the literature regarding the stability of the Cr(III)-hydroxide captured in the after-treatment sludge, and make plans to experimentally study the pathways for Cr(III) — the non-toxic form of chromium — to oxidize back to toxic Cr(VI), so as to determine ways to prevent this from happening.