Aluminiumhydroxychlorid-Flockungsmittel aus dem Kupferrecycling aus Abfällen der Leiterplattenproduktion

The production of printed circuit boards using the printing process produces considerable quantities of copper-containing etching solutions. The copper is recovered from the ammoniacal etching baths by cementation with aluminum waste at ≥ 99 % Cu yield rates. Instead of the usual landfilling, the aluminum-containing solution is processed into a coagulant which can be used in the treatment of mining tailings and wastewater. The aluminum oxychloride produced in this way was characterized in detail and its effectiveness as a flocculant for a finely dispersed system (kaolin suspension) was investigated and confirmed in a jar test.     

聚磷酸铵与次磷酸铝的共微胶囊制备及其在阻燃聚丙烯中的应用

以三聚氰胺-甲醛树脂（MF）为囊材、聚磷酸铵（APP）和次磷酸铝（AHP）为芯材，制备出共微胶囊化阻燃剂M（A-A）。通过傅里叶变换红外光谱、扫描电子显微镜及溶解度测试等方法来表征MF的包覆效果；采用垂直燃烧测定仪、极限氧指数仪和锥形量热仪等设备考察M（A-A）对聚丙烯（PP）的阻燃效果；通过冲击和拉伸实验对复合材料的力学性能进行表征。结果表明，MF树脂成功包覆并有效提高了A-A的耐水性能；添加相同质量的M（A-A）和A-A，前者明显降低热释放速率（R_HRR）和总热释放量（H_THR），对PP的阻燃效果更好。添加阻燃剂后，复合材料的冲击强度先提高后降低，经过微胶囊化处理的阻燃剂对材料的拉伸性能损伤更小。     

Recovery of vinyl chloride from by-streams of polyvinyl chloride production by TPSA in a multitubular adsorber

This work aims at developing an efficient and feasible adsorption-based separation process for the separation of vinyl chloride and nitrogen, on activated carbon, by employing a multitubular packed bed geometry, with adsorbent material inside the tubes. Using this geometry, a 2-dimensional mathematical model of a temperature pressure swing adsorption process was used to developed a 6-step three multitubular adsorbers system capable of separating and purifying an industrial scale gas stream of a 40:60% (v/v) vinyl chloride/nitrogen mixture into a 95% (v/v) vinyl chloride stream and a nitrogen stream with a vinyl chloride limit concentration of 8 ppm (w/w). The process reported energy consumption of 4.88 × 10⁶ J/kg_VCM and recovery capacity of 24.35 kg_VCM/(m³_unit h). The multitubular geometry enabled the use of lower adsorbent loads, shorter cycle times, and lower regeneration temperatures. An equivalent 1-dimensional model has also shown to satisfactorily estimate the performance of the current equipment.     

Performance Evaluation and Biodegradation Study of Polyvinyl Chloride Films with Castor Oil-based Plasticizer

In the present study, a renewable resource-based plasticizer was synthesized by the lipase-catalyzed esterification reaction of furfuryl alcohol (FA) and castor oil fatty acid (COFA). The resultant ester (FA-COFA ester) was used as secondary plasticizers to the polyvinyl chloride (PVC) films. The PVC films were formulated using the combination of a conventional plasticizer di-butyl phthalate (DBP) and FA-COFA ester as a secondary plasticizer at different concentrations. Films were characterized by X-ray diffraction analysis, scanning electron microscopy, thermal analysis, mechanical performance, and migration stability. A biodegradability study of the PVC films showed increased degradability with increasing concentration of the FA-COFA ester in the PVC film. The study showed that ester of FA and COFA could be a substitute of DBP by as much as 80% of the total plasticizer with improved elongation and tensile properties, and such a kind of sustainable resource-based PVC blend films could be used as a good packaging material with biodegradable property.     

Inferring kinetic dissolution of NaCl in aqueous glycol solution using a low-cost apparatus and population balance model

An experimental methodology for inferring brine dissolution rate in monoethylene glycol (MEG) solutions at different temperatures using a webcam combined with a mathematical model is presented. The measurement system is designed to track the RGB (red, green, and blue) colour variations during the dissolution process. A dynamic model augmented with the population balance equation is applied to describe the dissolution process. Moreover, the dissolution rate is consistently related to the temperature and MEG concentration through the driving force based on the Gibbs energy and chemical affinity. The applied low-cost measurement apparatus proved to be a useful resource for tracking the dissolution dynamics in a wide range of undersaturation.     

Preparation and performance of poly(lactic acid)/amidated ammonium citrate intercalated saponite nanocomposites

ABSTRACT

In this article, a novel method, amidation, was used to modify saponite. Amidated ammonium citrate intercalated saponite (Aa-saponite) was synthesized by amidation reaction. The structure of Aa-saponite was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), demonstrating that the saponite was successfully amidated. Polylactic acid/amidated ammonium citrate intercalated saponite nanocomposites (PLA/Aa-saponite) were prepared by melt blending. Mechanical tests demonstrated that the addition of Aa-saponite (0.3 wt%) improved the impact strength of PLA. A series of performance analysis results showed that A-saponite improved the comprehensive performance of PLA, such as mechanical, thermal stability, crystallization and rheological properties.     

Synthesis of lignosulfonate-acrylamide-dimethyldiallylammonium chloride copolymer and its flocculation performance

In this work, lignosulfonate-acrylamide-dimethyldiallylammonium chloride (LAD) terpolymer was designed and synthesized by microwave-assisted graft polymerization. The optimal synthetic process was obtained as follows: the monomer ratio was 1:4:4, the amount of initiator was 0.9% (w/w), the monomer solid content was 21 wt %, and the reaction time was 14 min with the microwave power of 280 W. Furthermore, the flocculation performance of LAD was verified by removing acid black-172 dye wastewater. At the LAD dosage of 350 mg L⁻¹, the maximum color removal ratio reached 99.8% in 100 mg L⁻¹ of dye wastewater. The dynamics of dye removal reached higher than 90% after 20 s. The flocculant can maintain color removal ratio more than 98% in a wide flocculant dosage and environmental pH. The flocculation mechanism was mainly electrical neutralization and bridging effect. In general, it is a promising candidate in wastewater treatment in terms of cost, synthetic method, and effectiveness. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48560.     

Alkali-doped hyperbranched cross-linked polybenzimidazoles containing benzyltrimethyl ammoniums with improved ionic conductivity as alkaline direct methanol fuel cell membranes

Development of anion exchange membranes (AEMs) with good performance, such as high conductivity, good alkaline stability and mechanical strength, has been a hot topic for the fuel cell application. Here, a novel kind of hyperbranched cross-linker decorated with quaternary ammonium groups was introduced to polybenzimidazole (PBI) membranes and QOPBI-x membranes (where x is the weight ratio of the hyperbranched cross-linker). Compared with the linear OPBI membrane (0.091 S cm⁻¹), QOPBI-x membranes displayed an improved ionic conductivity (up to 0.122 S cm⁻¹) at 60°C after they were doped in 6 M KOH for 7 days. The KOH-doped QOPBI-x membranes also exhibited a high tensile strength (54.5-61.7 MPa) and superior alkaline stability. There is almost no decline in the ionic conductivity after being immersed in a 6 M KOH solution for 30 days. In addition, the alkaline direct methanol fuel cell (ADMFC) performance based on the KOH-doped OPBI and QOPBI-x membranes is described. The QOPBI-15 membrane displayed good performance (75.6 mW cm⁻²), which is 33.3% higher than the OPBI membrane (56.7 mW cm⁻²).     

Polyaniline sensitized Pt@TiO2 for visible-light-driven H2 generation

Polyaniline is a typical conducting polymer with high migration electron rate, good stability, eco-friendly properties, and high absorption coefficients for visible light. In the present study, polyaniline decorated Pt@TiO₂ for visible light-driven H₂ generation is reported for the first time. The above-mentioned nanocomposite is prepared through a simple oxidative-polymerization and characterized by infrared spectroscopy, transmission electron microscopy, X–ray diffraction, thermogravimetric analysis, and ultraviolet–visible diffuse reflectance spectra. Polyaniline modification improves the absorption of the nanocomposite in visible light region via a photosensitization effect similar to dye–sensitization but does not influence the crystal structure and size of Pt@TiO₂. The polyaniline modified Pt@TiO₂ exhibits a remarkable visible light activity (61.8 μmol h⁻¹ g⁻¹) and good stability for H₂ generation (with an average apparent quantum yield of 10.1%) with thioglycolic acid as an electron donor. This work provides new insights into using conducting polymers, including polyaniline, as a sensitizer to modify Pt@TiO₂ for visible-light hydrogen generation.