Terahertz Absorption Characteristics of the Sodium Carboxymethyl Cellulose Colloid Based on Microfluidic Technology

Sodium carboxymethyl cellulose is a type of macromolecular chemical substance that is widely used in the industry for food thickening. In this study, terahertz and microfluidic technologies were combined, and a microfluidic chip with a channel depth of 50 μm was fabricated to carry samples. The terahertz characteristics of the sodium carboxymethyl cellulose colloid were studied at different concentrations and applied electric fields. The obtained results showed that different concentrations of sodium carboxymethyl cellulose have different time-domain spectra; with an increase in concentration, the terahertz transmittance of sodium carboxymethyl cellulose decreased. Under the applied electric field treatment, the longer the electric field acting time is, the higher the terahertz transmission intensity is. This approach is a safe and reliable new method for the determination of sodium carboxymethyl cellulose concentration, which provides technical support for the in-depth study of sodium carboxymethyl cellulose.

Effect of fouling resistance in heat exchanger and the crystal form of CaCO3 in hard circulating cooling water with electrostatic field and alternating current electric field

The effect of high voltage electrostatic field and high voltage alternating current electric field on the heat exchanger surface fouling under the condition of hard water was investigated. The Ca2+ concentration in two water conditions was 12 mmol/L. The Mg2+ concentration was 10 mmol/L and 12 mmol/L respectively. The concentration changed with the Mg2+ concentration. X-ray diffraction and Scanning electron microscope results confirmed that the main crystal phases of the scale samples consist of calcite and aragonite. The high voltage electrostatic treatment can promote scale growth under both water quality conditions. However, the high voltage alternating current electric field treatment shows a good scale inhibition effect under both water quality conditions, and the scale inhibition effect is best when both Ca2+ and Mg2+ concentrations are 12 mmol/L, and the average scale inhibition rate reaches 47.58%. When the calcite content of the scale sample is significantly higher than that of aragonite, Mg2+ affects the growth and solubility of crystals. On the other hand, the high voltage alternating current electric field treatment can effectively extend the fouling induction period of the adherent scale on the heat exchanger surface, which is favorable for heat exchanger fouling.

Operando Investigation of the Locally Enhanced Electric Field Treatment (LEEFT) Harnessing Lightning-Rod Effect for Rapid Bacteria Inactivation

The growth of undesired bacteria causes numerous problems. Here, we show that locally enhanced electric field treatment (LEEFT) can cause rapid bacteria inactivation by electroporation without any side reactions. The bacteria inactivation is studied in situ at the single-cell level on a lab-on-a-chip that has nanowedge-decorated electrodes. Rapid bacteria inactivation occurs specifically at nanowedge tips where the electric field is enhanced due to the lightning-rod effect. The mechanism study shows that the bacteria inactivation is caused by electroporation induced by the locally enhanced electric field. The bacteria inactivation performance depends on the strength of the enhanced electric field instead of the applied voltage, and no ROS generation is detected when >90% bacteria inactivation is achieved. Quick membrane pore closure under moderate LEEFT indicates that electroporation is the predominant mechanism. LEEFT only requires facile treatment to achieve bacteria inactivation, which is safe for treating delicate samples and energy-efficient for large scale applications. The findings in this work can provide strong supports for the future applications of LEEFT.