Dr Donglin Zhao

In chemical education, repetitive and large-scale motion of material in a chemical reaction could effectively capture students' attention and stimulate their interests to further explore the underlying science. Gallium-based liquid metals are more safe and suitable for some classroom demonstrations than mercury to introduce chemical principles. In this article, we describe a visually striking experiment using Ga-based liquid metal. Repetitive and large-scale deformation of liquid metal was observed in an acidified solution of either copper(II) chloride or ferric(III) chloride. To elucidate the mechanism of deformation, the chemical reaction and the interfacial tension are discussed. Deformation can be attributed to a spatial and temporal imbalance of the interfacial tension on the liquid metal induced by the chemical reactions. The simple setups and readily available chemicals enable this experiment to be a suitable and safe classroom demonstration.

Tofu, a traditional Chinese food, is now popular worldwide.However,few people notice the chemistry that is involved in its production.To shed light on this, we have designed a simple demonstration forlower-level undergraduates in organic chemistry or biochemistry coursesto help them understand the chemistry principles that underlie thecurdling step in tofu processing. Raw soymilk is relatively stablewithout heating, even with the addition of coagulants. However, heattreatment denatures the soy proteins in soymilk, which makes themmore amenable to coagulation. This coagulation is further promotedwith salt coagulants, such as calcium gluconate, zinc gluconate, andcalcium lactate. Acid coagulants such as white vinegar or grape, orange,and lemon juice can also induce coagulation due to their acidic properties.Based on our results and on previous reports, we illustrate the curdlingmechanism in this work. This demonstration can also be used as anat-home experiment during lab closure situations, such as a pandemic,and can arouse students' curiosity about the coagulation ofother food proteins and the process of making alternative tofu.

Micropumps have an important influence on the field of microfluidics, with particular interest in pumps based on liquid metal that operate without mechanical moving parts. While previous research has primarily focused on pumping alkaline media, this article aims to advance the field by demonstrating a liquid metal pump suitable for acidic environments. A key strategy involves reducing the interfacial tension between the liquid metal and the surrounding solution through the addition of surface-active anions (I-). Theoretical analysis first evaluates the effectiveness of this approach. These experimental results confirm that increasing KI concentrations leads to a decrease in interfacial tension, enabling the deformation and actuation of liquid metal droplets at lower voltages compared to acidic media alone. Subsequently, an acidic media pump is constructed, and various parameters influencing its performance are examined, including acidity, iodide anion concentration, voltage, frequency, and droplet volume. This research offers strategies for developing liquid metal pumps with high flow rates and low energy consumption, thereby expanding the application potential of liquid metal in microfluidics.

In this study, deformation behaviors of gallium-based liquid metals in acidified cupric sulfate or cupric chloride solutions with varying concentrations of chloride anion or sulfate anion were investigated to explore their potential applications in soft machines and electronics. Gallium-based liquid metals are known for their unique deformability, making them promising materials for various fields. Previous research has shown that deformation of the liquid metal can be achieved in the presence of acidified cupric or ferric salts. However, the specific influence of different anions on the deformation process remains unclear. Our findings indicate that the deformation rate of the liquid metal increases with higher concentrations of chloride ions and decreases with higher concentrations of sulfate ions in the solution. UV-vis absorbance spectra of the solutions were analyzed to identify the formation of hydrated cupric cations. It was observed that increasing the concentration of Cl- ions promotes the formation of cupric-chloro complexes, thereby reducing the concentration of hydrated cupric ions in the solution. Furthermore, the addition of sulfate ions to the solution enhances the ionic strength of the medium, leading to the dissociation of cupric-chloro complexes. Additionally, sulfate ions can form insoluble layers with gallium ions, which impede the deformation of the liquid metal. The deformation rate of the liquid metal was found to be inversely correlated with the concentration of cupric ions in the solution. These results provide valuable insights into the deformable behavior of gallium-based liquid metals and their potential applications in liquid metal-based soft robots. This study highlights the importance of understanding the role of different anions in the deformation process of liquid metals, shedding light on the design and optimization of soft machines and electronics utilizing these materials.

Interfacial,or surface tension, is a significant topic in chemicaleducation. This paper describes the directional motion of gallium-basedliquid metal drops, resulting from a difference of interfacial tensionacross the drop. This demonstration can engage students in discoveringthe underlying chemical principles. A mechanism for the drop'sdirectional motion is proposed to provide insight into this intriguingphenomenon. It appears that unbalanced chemical environments causedifferent physical or chemical processes to occur on each hemisphereof the drop, such as a pH difference, redox reactions, galvanic replacement,or adsorption. As a result, a difference in the interfacial tensionacross the drop is generated, providing the driving force that actson the drop. This demonstration can be used to introduce the fundamentalprinciples in chemical reactions, such as redox activity, electricaldouble layer formation, and interfacial tension.

•Novel experimental investigation of wax deposition behaviour in pipelines with varying curvature.•Demonstration of higher deposition rates in curved pipes compared to straight pipes.•Integration of bend parameters into a new correlation model for wax deposition prediction.•Highlighting the underestimated effects of Brownian diffusion and gravity settling on wax deposition.•Contribution to advancing the understanding of wax deposition phenomena. This study investigates the intricate phenomenon of wax deposition in oil pipelines, with a primary focus on enhancing the understanding of wax deposition mechanisms. Special attention is given to the role of pipe curvature in influencing these deposition processes, exploring how bends in pipeline structures may alter the behaviour of wax deposition, potentially leading to operational challenges. A novel flow rig was designed and commissioned to simulate wax deposition in straight pipes and pipes with 45° and 90° bends at both horizontal and inclined positions. The objective of the work is to quantify the impact of flow parameters, such as the temperature and flow rate, on wax buildup under different pipe configurations. The results demonstrate that the temperature and flow rate are critical factors influencing wax deposition processes. Specifically, lower temperatures (ranging from 10 °C to 30 °C) and laminar flow conditions (Re 

A mechanistic model on catalyst deactivation by coke formation in a continuous stirred tank reactor (CSTR) has been developed in the paper. Catalyst deactivation by coke formation was treated as a surface reaction. Four reaction mechanisms representing coke formation through different routes were proposed. The evolved system of ordinary differential equations (ODEs) was solved numerically using MATLAB. This approach was validated by applying it to the skeletal isomerization of 1-pentene over ferrierite. Simulation results were compared qualitatively to those obtained from the literature. Simulation results indicated that coke formation is an extremely rapid process with fast formation of coke components on the strongest acid sites leading to final coke. The coke deposition is slower at higher residence times resulting in more stable product formation and weaker deactivation. The results obtained from this work revealed that the developed model is indeed able to successfully demonstrate the most essential features of catalyst deactivation by coke formation and are in agreement with the findings in the literature. Future work is aimed to extend the study to different reactors such as a plug flow reactor, in addition to analysis of the reaction system's sensitivity to variables such as temperature and pressure.