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Reducing the cost of hydrogen transport is an important priority for the proliferation of clean hydrogen to decarbonize the economy. It is possible to alleviate the hydrogen transportation costs by delivering them via existing natural gas pipeline infrastructure. This strategy, however, necessitates the dilution of hydrogen by blending it with natural gas as hydrogen embrittlement pipeline materials. In this work, we deploy high-temperature polymer electrolyte membrane electrochemical hydrogen pumps (HT-PEM EHPs) to purify hydrogen from dilute hydrogen–natural gas mixtures (5 to 20 vol % hydrogen). Interestingly, we observe that activation overpotentials govern HT-PEM EHP polarization when feeding dilute hydrogen mixtures. Pressurizing the anode to 1.76 barabs enables us to ameliorate interfacial mass transfer resistance and achieve an EHP limiting current density of 1.4 A cm–2 with a 10 vol % of hydrogen in a natural gas feed. The HT-PEM EHP showed a small degradation rate, 44 μV h–1, during a 100 h durability test. 

Plasma protein therapies are used by millions of people across the globe to treat a litany of diseases and serious medical conditions. One challenge in the manufacture of plasma protein therapies is the removal of salt ions (e.g., sodium, phosphate, and chloride) from the protein solution. The conventional approach to remove salt ions is the use of diafiltration membranes (e.g., tangential flow filtration) and ion-exchange chromatography. However, the ion-exchange resins within the chromatographic column as well as filtration membranes are subject to fouling by the plasma protein. In this work, we investigate the membrane capacitive deionization (MCDI) as an alternative separation platform for removing ions from plasma protein solutions with negligible protein loss. MCDI has been previously deployed for brackish water desalination, nutrient recovery, mineral recovery, and removal of pollutants from water. However, this is the first time this technique has been applied for removing 28% of ions (sodium, chloride, and phosphate) from human serum albumin solutions with less than 3% protein loss from the process stream. Furthermore, the MCDI experiments utilized highly conductive poly(phenylene alkylene)- based ion exchange membranes (IEMs). These IEMs combined with ionomer-coated nylon meshes in the spacer channel ameliorate Ohmic resistances in MCDI improving the energy efficiency. Overall, we envision MCDI as an effective separation platform in biopharmaceutical manufacturing for deionizing plasma protein solutions and other pharmaceutical formulations without a loss of active pharmaceutical ingredients. 

The capstone chemical engineering senior process design course at Penn State in spring 2023 tasked students with designing a caustic soda process to partially meet the global demand for commoditized sodium hydroxide. This article disseminates our experience teaching senior chemical engineering students the core tenets of electrochemical engineering in a single class period for designing an electrolytic caustic soda process. In this E-Chem Education article, we relate key concepts found in chemical engineering (such as sizing up a reactor volume), which chemical engineering seniors are adept with, to electrochemical engineering principles (e.g., current density, voltage, and membrane electrode assembly area) for sizing up and costing out a chlor-alkali electrolyzer. Furthermore, we also discuss alternative electrolyzer designs outside the traditional chlor-alkali process, such as oxygen depolarized cathode (ODC) chlor-alkali and bipolar membrane electrodialysis (BPMED), for caustic soda production and the pros and cons of the alternative process designs. 

The case for making Electrochemical Science and Engineering part of the core chemical engineering curriculum 

This work reveals how electrode binders affect reaction kinetics, ionic conductivity, and gas transport in electrochemical hydrogen pumps (EHPs). Using a blend of phosphonic acid and perfluorosulfonic acid ionomers as the electrode binder, an EHP was operated at 5 A cm⁻². 

The palette of applications for bipolar membranes (BPMs) has expanded recently beyond electrodialysis as they are now being considered for fuel cell and electrolysis applications. Their deployment in emerging electrochemical technologies arises from the need to have a membrane separator that provides disparate pH environments and to prevent species crossover. Most materials research for BPMs has focused on water dissociation catalysts and less emphasis has been given to the design of the polycation–polyanion interface for improving BPM performance. Here, soft lithography fabricated a series of micropatterned BPMs with precise control over the interfacial area in the bipolar junction. Polarization experiments showed that a 2.28× increase in interfacial area led to a 250 mV reduction in the onset potential. Additionally, the same increase in interfacial area yielded marginal improvements in current density due to the junction region being under kinetics-diffusion control. A simple physics model based on the electric field of the junction region rationalized the reduction in the overpotential for water dissociation as a function of interfacial area. Finally, the soft lithography approach was also conducive for fabricating BPMs with different chemistries ranging from perfluorinated polymer backbones to alkaline stable poly(arylene) hydrocarbon polymers. These polymer chemistries are better suited for fuel cell and electrolysis applications. The BPM featuring the alkaline stable poly(terphenyl) anion exchange membrane had an onset potential of 0.84 V, which was near the thermodynamic limit, and was about 150 mV lower than a commercially available variant.