By Marcus Gay, NM WRRI Student Program Coordinator
In New Mexico, heavy metals such as lead are being released into waterways and groundwater from over 15,000 abandoned mines. Excess lead in groundwater can be harmful to humans, making heavy metals water contamination a serious environmental issue in New Mexico. Therefore, it is important to explore effective techniques to remove lead from groundwater. This is the focus of Jiuling Yu’s research.
Jiuling Yu is a PhD candidate at New Mexico State University’s (NMSU) Chemical & Materials Engineering Department. This year, Yu received an NM WRRI Student Water Research Grant entitled, Wastewater-Treatment Algae-Derived Hydrochar for Heavy Metal Adsorption and Recycling. The objectives of the project are to (1) investigate the effects of pretreatments (oil extraction and CO2 activation) on the adsorption capacity of lead, (2) explore the adsorption capacity on lead Pb(Ⅱ) for waste hydrochar derived from hydrothermal liquefaction (HTL)-algae, and (3) evaluate the feasibility of recycling lead-adsorbed hydrochar as anode materials in lithium-ion batteries.
Adsorption is an attractive strategy for removal of Pb(Ⅱ) due to its low-cost and simple operation condition. Recently, carbon derived from abundant and renewable biomass has been considered as a high-efficiency adsorbent to remove Pb(Ⅱ) in the treatment process. Algae is an ideal renewable resource due to its high-rate growth, strong CO2-mitigation potential, good adaptability in variable climatic conditions, and vast possibility of large-scale artificial cultivation. However, it remains challenging to dispose of Pb-adsorbed hydrochar in a sustainable way. One potential solution is for Pb-adsorbed hydrochar to be further developed as the anode material in lithium-ion batteries.
Hydrochar was provided by Dr. Catherine Brewer’s group at NMSU. Two types of pretreatments (oil-extracted process and CO2 activation) were performed before adsorption experiments. To evaluate the adsorption capacity of Pb(Ⅱ ), a 1000 mg/L Pb(Ⅱ ) solution was first prepared by dissolving a measured amount of Pb(NO3)2 in de-ionized water as the stock lead solution. The targeted solutions were prepared by diluting stock solution with a calculated ratio of de-ionized water. Then the adsorption capacity was calculated using an equation. The electrochemical experiments out using CR2025 coin cells with as-obtained working electrode, separator, and lithium chip in an argon-filled glove-box. The electrochemical performance experiments will continue to be evaluated.
Primarily, Yu and her team’s work may prove beneficial for wastewater utilities due to the potential application of wastewater-treatment algae. Secondly, regarding the effective adsorption capacity, this work provides preliminary data to other researchers who are studying biomass-based adsorbents which will help decrease lead concentration in groundwater. Lastly, companies involved in work with lithium ion batteries could benefit from the results of this project by recycling Pb-based hydrochar as anode materials.
Yu, under the guidance of her Faculty Advisor Dr. Hongmei Luo, a Professor of Chemical Engineering and the Associate Dean of Research in the College of Engineering, presented her research at the NM WRRI 64th Annual New Mexico Water Conference in Pojoaque, New Mexico. Yu received a bachelor’s degree from Beijing University of Chemical Technology in her home country of China, and received a master’s degree from University College Dublin in Ireland. Yu plans to graduate in 2020, and after graduation, plans to continue her research as a postdoctoral researcher.