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化学机械抛光 1

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Ionic strength directed self-assembled polyelectrolyte single-bilayer membrane for low-pressure nanofiltration

《化学科学与工程前沿（英文）》 2022年第16卷第5期页码 699-708 doi: 10.1007/s11705-021-2093-3

摘要： Layer-by-layer assembly is a versatile technique for fabricating nanofiltration membranes, where multiple layers of polyelectrolytes are usually required to achieve reasonable separation performance. In this work, an ionic strength directed self-assembly procedure is described for the preparation of nanofiltration membranes consisting of only a single bilayer of poly(diallyldimethylammoniumchloride) and poly(sodium-4-styrenesulfoate). The influence of background ionic strength as well as membrane substrate properties on the formation of single-bilayer membranes are systematically evaluated. Such a simplified polyelectrolyte deposition procedure results in membranes having outstanding separation performance with permeating flux of 14.2 ± 1.5 L∙m^–2∙h^–1∙bar^–1 and Na₂SO₄ rejection of 97.1% ± 0.8% under a low applied pressure of 1 bar. These results surpass the ones for conventional multilayered polyelectrolyte membranes. This work encompasses an investigation of ionic strength induced coiling of the polyelectrolyte chains and emphasizes the interplay between-polyelectrolyte chain configuration and substrate pore profile. It thus introduces a new concept on the control of membrane fabrication process toward high performance nanofiltration.

关键词： layer-by-layer self-assembly single bilayer nanofiltration membrane desalination

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Enhancement of sludge gravitational thickening with weak ultrasound

Panyue ZHANG, Tian WAN, Guangming ZHANG

《环境科学与工程前沿（英文）》 2012年第6卷第5期页码 753-760 doi: 10.1007/s11783-011-0368-5

摘要： Gravitational thickening is the prevailing method to reduce sludge volume but the process is slow and usually requires addition of polyelectrolyte(s). This paper investigated the potential benefits of sonication on enhancing the sludge gravitational thickening with very low energy dose, so called “weak ultrasound”. Results showed that weak sonication significantly changed the sludge settlability and the main mechanism was release of the loosely bounded extracellular polymeric substances. The changes in sludge behaviors by sonication were strongly influenced by power density and sonication duration. Lower sound frequency was slightly better than higher frequency. Weak sonication (<680 kJ·kg DS) improved the sludge gravitational thickening while high ultrasonic energy deteriorated the process. Considering both the sludge thickening efficiency and energy consumption, the optimum conditions were 0.15 W·mL , 7 s, and 25 kHz. Under such conditions, the energy dose was only 155 kJ·kg DS, much lower than literature reports, and the sludge settling time was shortened from 24 h to 12?h. Weak sonication could substitute expensive polyelectrolyte coagulant for sludge thickening. Combination of weak sonication and polyelectrolyte could further reduce the settling time to 6 h. The final water content of the thickened sludge was not changed after sonication or polyelectrolyte addition.

关键词： activated sludge sonication settlability dry weight extracellular polymeric substances polyelectrolyte

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A cytoprotective graphene oxide-polyelectrolytes nanoshell for single-cell encapsulation

Luanying He, Yulin Chang, Junhao Zhu, Ying Bi, Wenlin An, Yiyang Dong, Jia-Hui Liu, Shihui Wang

《化学科学与工程前沿（英文）》 2021年第15卷第2期页码 410-420 doi: 10.1007/s11705-020-1950-9

摘要： Graphene oxide (GO) has been increasingly utilized in the fields of food, biomedicine, environment and other fields because of its benign biocompatible. We encapsulated two kinds of GO with different sizes on yeast cells with the assistance of polyelectrolytes poly (styrene sulfonic acid) sodium salt (PSS) and polyglutamic acid (PGA) (termed as Y@GO). The result does not show a significant difference between the properties of the two types of Y@GO (namely Y@GO1 and Y@GO2). The encapsulation layers are optimized as Yeast/PGA/PSS/PGA/GO/PGA/PSS based on the morphology, dispersity, colony-forming unit, and zeta potential. The encapsulation of GO increases the roughness of the yeast. It is proved that the Y@GO increases the survival time and enhance the activity of yeast cells. The GO shell improves the resistance of yeast cells against pH and salt stresses and extends the storage time of yeast cells.

关键词： GO yeast polyelectrolyte cytoprotection nanomaterials

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静电自组装制备复合磨粒及其对铜的抛光特性研究

黄亦申,许雪峰,姚春燕,胡建德,彭伟

《中国工程科学》 2012年第14卷第10期页码 82-89

摘要：

研究苯代三聚氰胺甲醛（BGF）微球与阳离子型聚电解质聚二烯丙基二甲基氯化铵（PDADMAC）、阴离子型聚电解质聚4－苯乙烯璜酸钠（PSS）之间的吸附特性，利用静电自组装技术改变和控制BGF微球的荷电特性，制备出不同形式的PEi BGF/SiO2复合磨粒，以Zeta电位、透射电子显微镜（TEM）和热重分析（TG）等手段对复合磨粒进行了表征，并利用这些复合磨粒制备了铜片抛光用的复合磨粒抛光液。抛光试验表明，吸附在聚合物微球表面和游离于抛光液中的SiO2磨粒在抛光中均起到材料去除作用。传统单一SiO2磨粒抛光液的铜材料去除率为264 nm/min，PE0 BGF/SiO2混合磨粒抛光液的铜材料去除率为348 nm/min，PE3 BGF/SiO2复合磨粒抛光液的铜材料去除率为476 nm/min。经上述3种抛光液抛光后的铜表面，在5 μm×5 μm范围内，表面粗糙度Ra从0.166 μm分别降至3.7 nm、2.6 nm和1.5 nm，峰谷值Rpv分别小于20 nm、14 nm和10 nm，复合磨粒抛光液对铜片有良好的抛光性能。

关键词：化学机械抛光抛光液复合磨粒聚电解质铜片