[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Ongoing progress on novel nanocomposite membranes for the separation of heavy metals from contaminated water.

Rigid robots have taken on a variety of automated manufacturing tasks and have made a huge contribution to industrial development; however, they are not suitable for further wearable applications due to their rigid and bulky structure, poor environmental adaptability, and low safety. Soft robots, which are mainly fabricated with ﬂexible or elastomeric materials, can easily adjust to environmental changes and accomplish complex tasks, offering a new paradigm to achieve human–machine compliance. Soft robots do not replace rigid robots but add diverse features for softer robotic applications. In particular, the use of flexible actuators in robotic systems can realize certain intelligent functions, enrich soft robotic systems and migrate academic research to engineering applications. Currently, the application of flexible actuators in soft robotic fields is still at the embryonic stage. However, tremendous application spaces can be envisaged when combining flexible actuators with soft wearable robotics. Therefore, the current flexible actuators that rely on different external stimuli are addressed herein, and their materials, designs, and approaches suitable for soft robotic applications are highlighted. The application advancement and future perspective of flexible actuator prototypes toward various soft robotics are also discussed.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/aisy.201900077

Flexible Actuators for Soft Robotics

Biomineralization induced by microorganisms has become a hot spot in the field of carbonate sedimentology; however, the mechanisms involved still need to be explored. In this study, the bacterium Bacillus subtilis J2 (GenBank MG575432) was used to induce the precipitation of calcium carbonate minerals at Mg/Ca molar ratios of 0, 3, 6, 9, and 12. Bacillus subtilis J2 bacteria released ammonia to increase pH, but the ammonia released only made the pH increase to 8.25. Carbonic anhydrase was also produced to catalyze the hydration of carbon dioxide, and this process released carbonate and bicarbonate ions that not only increased pH but also elevated carbonate supersaturation. The biominerals formed at a Mg/Ca molar ratio of 0 were spherulitic, elongated, dumbbell-shaped, and irregularly rhombohedral calcite; at a Mg/Ca molar ratio of 3, the biominerals were calcite and aragonite, the weight ratio of calcite decreased from 26.7% to 15.6%, and that of aragonite increased from 73.3% to 84.4% with increasing incubation time. At higher Mg/Ca molar ratios, the biominerals were aragonite, and the crystallinity and thermal stability of aragonite decreased with increasing Mg/Ca molar ratios. FTIR results showed that many organic functional groups were present on/within the biominerals, such as C–O–C, N–H, C=O, O–H, and C–H. HRTEM-SAED examination of the ultra-thin slices of B. subtilis J2 bacteria showed that nano-sized minerals with poor crystal structure had grown or been adsorbed on the EPS coating. The EPS of the B. subtilis J2 strain contained abundant glutamic acid and aspartic acid, which could be deprotonated in an alkaline condition to adsorb Ca2+ and Mg2+ ions; this made EPS act as the nucleation sites. This study may provide some references for further understanding of the mechanism of biomineralization induced by microorganisms.

https://www.mdpi.com/2075-163X/9/4/218/pdf

Mechanism of Biomineralization Induced by Bacillus subtilis J2 and Characteristics of the Biominerals

Membrane fouling is seen as the main culprit that hinders the widespread of membrane application in liquid-based filtration. Therefore, fouling management is key for the successful implementation of membrane processes, and it is done across all magnitudes. For optimum operation, membrane developments and surface modifications have largely been reported, including membrane surface patterning. Membrane surface patterning involves structural modification of the membrane surface to induce secondary flow due to eddies, which mitigate foulant agglomeration and increase the effective surface area for improved permeance and antifouling properties. This paper reviews surface patterning approaches used for fouling mitigation in water and wastewater treatments. The focus is given on the pattern formation methods and their effect on overall process performances.

https://www.mdpi.com/2073-4360/11/10/1687/pdf

Membrane Surface Patterning as a Fouling Mitigation Strategy in Liquid Filtration: A Review.

Hexavalent chromium is one of the main heavy metal pollutants. As the environmental legislation becomes increasingly strict, seeking new technology to treat wastewater containing hexavalent chromium is becoming more and more important. In this research, a novel modified ultrafiltration membrane that could be applied to adsorb and purify water containing hexavalent chromium, was prepared by polyvinylidene fluoride (PVDF) blending with 2-aminobenzothiazole via phase inversion. The membrane performance was characterized by evaluation of the instrument of membrane performance, infrared spectroscopy (FTIR), scanning electron microscope (SEM), and water contact angle measurements. The results showed that the pure water flux of the PVDF/2-aminobenzothiazole modified ultrafiltration membrane was 231.27 L/m2·h, the contact angle was 76.1°, and the adsorption capacity of chromium ion was 157.75 µg/cm2. The PVDF/2-aminobenzothiazole modified ultrafiltration membrane presented better adsorption abilities for chromium ion than that of the traditional PVDF membrane.

Preparation and Characterization of Novel Polyvinylidene Fluoride/2-Aminobenzothiazole Modified Ultrafiltration Membrane for the Removal of Cr(VI) in Wastewater

Photocatalytic ultrafiltration membranes have great potential advantages in future-water treatment systems. The preparation of photocatalytic ultrafiltration membranes and the selection of catalysts are the key to the development of photocatalytic ultrafiltration membranes. This paper reviews the research status, removal mechanism of pollutants, module design and applications of photocatalytic ultrafiltration membranes. The metal-doped TiO2 photocatalytic ultrafiltration membranes, nonmetal-doped TiO2 photocatalytic ultrafiltration membranes, semiconductor-doped TiO2 photocatalytic ultrafiltration membranes, co-doped TiO2 photocatalytic ultrafiltration membrans, and non-TiO2 system photocatalytic ultrafiltration membranes are introduced in detail. At the same time, it summarizes the removal of micro-pollutants in water, treatment of dyes in water, and applications in other aspects, demonstrating its potential for application in various areas of water treatment systems. Finally, the direction of future research is proposed.

/pdf/photocatalytic-ultrafiltration-membranes-based-on-visible-3utaw5604d.pdf

Photocatalytic ultrafiltration membranes based on visible light responsive photocatalyst: a review

Preparation and Characterization of Modified Polyvinylidene Fluoride/2-Amino-4-thiazoleacetic Acid Ultrafiltration Membrane for Purification of Cr(VI) in Water

The invention discloses an improved chitosan/sulfonated polyether sulfone cation exchange membrane and a preparing method thereof. The exchange membrane is prepared mainly with sulfonated polyether sulfone as the membrane substrate and phthaloyl chitosan or N-malely chitosan as the additive substance. The membrane has the advantages that the porosity of the cation exchange membrane is improved after modification, the membrane performance is greatly improved in combination with the mechanical strength, stability and high hydrophilia provided by the sulfonated polyether sulfone substrate, and the membrane can be well applied in the field of electrodialysis ion exchange membranes.

Improved chitosan/sulfonated polyether sulfone cation exchange membrane and preparing method thereof

The invention discloses a method for preparing lithium chloride by using four-compartment replacement reaction electrodialysis. A lithium salt solution, such as lithium sulfate, lithium carbonate or lithium bicarbonate, and a sodium chloride solution are fed into a feeding compartment II and a feeding compartment IV of a four-compartment replacement reaction electrodialysis device, so that under the action of electric field force, lithium ions in the feeding compartment II and chloride ions in the feeding compartment IV respectively pass through the cation exchange membrane and the anion exchange membrane, and a lithium chloride solution is obtained in the product compartment III; in addition, anions in the feeding compartment II and sodium ions in the feeding compartment IV pass through acation exchange membrane and an anion exchange membrane respectively, and a sodium salt solution is obtained in the product compartment I. According to the process, the pretreatment process of the raw materials is simplified, a large amount of hydrochloric acid does not need to be consumed, some impurity ions in the raw materials are removed while lithium carbonate is prepared, the purity of lithium chloride is improved, the difficulty of the aftertreatment process is reduced, and the method is a low-consumption, environment-friendly and recyclable lithium chloride preparation method.

Ma Zhun

Papers

Preparation and Characterization of Novel Polyvinylidene Fluoride/2-Aminobenzothiazole Modified Ultrafiltration Membrane for the Removal of Cr(VI) in Wastewater

Photocatalytic ultrafiltration membranes based on visible light responsive photocatalyst: a review

Preparation and Characterization of Modified Polyvinylidene Fluoride/2-Amino-4-thiazoleacetic Acid Ultrafiltration Membrane for Purification of Cr(VI) in Water

Improved chitosan/sulfonated polyether sulfone cation exchange membrane and preparing method thereof

Method for preparing lithium chloride by using four-compartment replacement reaction electrodialysis