High-Pressure Reverse Osmosis for Industrial Water Recycling: Permeate-Sided Pressure Drop as Performance-Limiting Factor

In the chemical industry large amounts of saline wastewater occur. Its disposal into rivers is a considerable burden to the ecosystem. To strive for a circular economy and enable a viable raw material recycling, energy-efficient concentration processes are requisite. High-pressure reverse osmosis meets this criterion, but its industrial application demands suitable membrane elements that withstand the exceptional operation conditions and provide sufficient performance. Hence, new requirements regarding the design of spiral-wound elements arise. To identify those, specific performance-limiting effects need a better understanding.     

Batch Tests for Optimisation of Solvent Composition and Process Flexibility of the CHALMEX FS-13 Process

ABSTRACT

Studies have been performed with the purpose of determining the optimal solvent composition of a Chalmers grouped actinide extraction (CHALMEX) solvent for the selective co-extraction of transuranic elements in a novel Grouped ActiNide EXtraction (GANEX) process. The solvent is composed of 6,6’-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo-[1,2,4]-triazin-3-yl)-[2,2’]-bipyridine (CyMe₄-BTBP) and tri-n-butyl phosphate (TBP) in phenyl trifluoromethyl sulfone (FS-13). The performance of the system has been shown to significantly depend on the ratios of the two extracting agents and the diluent to one another. Furthermore, the performance of the determined optimal solvent (10 mM CyMe₄-BTBP in 30% v/v TBP and 70% v/v FS-13) on various simulated PUREX raffinate solutions was tested. It was found that the solvent extracts all transuranic elements with high efficiency and good selectivity with regard to most other elements (fission products/activation products) present in the simulated PUREX raffinate solutions. Moreover, the solvent was found to extract a significant amount of acid. Palladium, silver, and cadmium were co-extracted along with the TRU-radionuclides, which has also been observed in other similar CHALMEX systems. The extraction of plutonium and uranium was preserved for all tested simulated PUREX raffinate solutions compared to experiments using trace amounts.     

Deconvoluting Energy Transport Mechanisms in Metal Halide Perovskites Using CsPbBr3 Nanowires as a Model System

Understanding energy transport in metal halide perovskites is essential to effectively guide further optimization of materials and device designs. However, difficulties to disentangle charge carrier diffusion, photon recycling, and photon transport have led to contradicting reports and uncertainty regarding which mechanism dominates. In this study, monocrystalline CsPbBr₃ nanowires serve as 1D model systems to help unravel the respective contribution of energy transport processes in metal-halide perovskites. Spatially, temporally, and spectrally resolved photoluminescence (PL) microscopy reveals characteristic signatures of each transport mechanism from which a robust model describing the PL signal accounting for carrier diffusion, photon propagation, and photon recycling is developed. For the investigated CsPbBr₃ nanowires, an ambipolar carrier mobility of μ = 35 cm² V⁻¹ s⁻¹ is determined, and is found that charge carrier diffusion dominates the energy transport process over photon recycling. Moreover, the general applicability of the developed model is demonstrated on different perovskite compounds by applying it to data provided in previous related reports, from which clarity is gained as to why conflicting reports exist. These findings, therefore, serve as a useful tool to assist future studies aimed at characterizing energy transport mechanisms in semiconductor nanowires using PL.     

Reusable Polyacrylonitrile-Sulfur Extractor of Heavy Metal Ions from Wastewater

Mercury, lead, and cadmium are among the most toxic and carcinogenic heavy metal ions (HMIs), posing serious threats to the sustainability of aquatic ecosystems and public health. There is an urgent need to remove these ions from water by a cheap but green process. Traditional methods have insufficient removal efficiency and reusability. Structurally robust, large surface-area adsorbents functionalized with high-selectivity affinity to HMIs are attractive filter materials. Here, an adsorbent prepared by vulcanization of polyacrylonitrile (PAN), a nitrogen-rich polymer, is reported, giving rise to PAN-S nanoparticles with cyclic π-conjugated backbone and electronic conductivity. PAN-S can be coated on ultra-robust melamine (ML) foam by simple dipping and drying. In agreement with hard/soft acid/base theory, N- and S-containing soft Lewis bases have strong binding to Hg²⁺, Pb²⁺, Cu²⁺, and Cd²⁺, with extraordinary capture efficiency and performance stability. Furthermore, the used filters, when collected and electrochemically biased in a recycling bath, can release the HMIs into the bath and electrodeposit on the counter-electrode as metallic Hg⁰, Pb⁰, Cu⁰, and Cd⁰, and the PAN-S@ML filter can then be reused at least 6 times as new. The electronically conductive PAN-S@ML filter can be fabricated cheaply and holds promise for scale-up applications.     

典型废玻璃回收厂区空气颗粒物及噪声分布特征研究

以某典型废玻璃回收厂区作为研究对象, 监测和分析了车间及厂区内部的噪声强度、空气颗粒物(PM_2.5、PM₁₀) 浓度等环境指标, 点位布设涵盖了车间入口、人工分拣、物料筛分、破碎、干法清洗等关键工艺环节; 其次, 解析了空气颗粒物的组分及形貌特征, 并对其在厂区及车间内部的时空分布特征进行了研究; 此外, 利用噪声控制模型模拟并分析了隔声罩对噪声的控制作用。结果表明, 生产车间中工作态的空气颗粒物浓度显著高于非工作态, 其中干法清洗区浓度最高, 其PM_2.5 浓度为3.725 mg/m³, PM₁₀浓度为4.055 mg/m³; 噪声监测结果显示生产车间内噪声强度较高, 达到99.5 dB, 而引入隔声罩后噪声强度可降至67 dB, 结果表明, 隔声罩可有效控制频率为125~1 000 Hz 的噪声。该研究可为废玻璃的绿色、高效回收处置提供理论基础和实践经验。     

The use of recycled low-density polyethylene films from protective prepreg for the development of nanocomposites with bentonite clay

Prepreg is a pre-impregnated composite fiber where a thermoset polymer matrix material is present. Before being used, these materials are kept at low temperatures and have a low-density polyethylene (LDPE) film for your protection. The increase in the use of structural composites based on prepregs causes an increase in the amount of protective LDPE film. This material is usually discarded or incinerated and can cause great damage to the environment. Thus, the present work aimed to study the feasibility of recycling up to 100% of protective LDPE (rLDPE) to develop blends-based nanocomposites with rLDPE/virgin LDPE (60/40, 70/30, 80/20, 90/10 and 100/0) with the addition of 5 wt% of compatibilizer agent (maleic anhydride grafted LDPE, LDPE-g-MA), and 1 wt% of bentonite (BNT) using a co-rotational twin-screw extruder, followed by hot pressing in a hydropneumatic press and die-cutting. Water absorption test, thermal aging resistance, morphological characterization by scanning electron microscopy, mechanical properties by Izod impact strength and tensile tests, and differential scanning calorimetry were performed. By the results, it was possible to verify the viability of 100% of the recycling of rLDPE. The results showed a good distribution of 1 wt% of BNT in the matrix, better mechanical properties when compared with virgin LDPE. Furthermore, the thermal properties, water absorption test, and thermal aging resistance showed no statistical differences between the samples. These results confirm the effectiveness and the environmental gain in the use of the recycled material.     

Synthesis and characterization of natural rubber-based telechelic oligomers via olefin metathesis

Metathesis degradation and functionalization of natural rubber (NR) were conducted with 1-hexene, 1-octene, 1-decene, 1-dodecene, trans-stilbene, and 4,4′-dibromo-trans-stilbene as chain transfer agents (CTAs) in presence of Grubbs 2nd generation catalyst to generate NR-based telechelic oligomers that had been a long-lasting challenge due to the structure and compositions of NR with various impurities. Orthogonal experiments were applied and the effects of the CTA type, CTA concentration, catalyst concentration, reaction time, and reaction temperature on the formation of telechelic oligomers were studied, indicating that the catalyst concentration was the major factor influencing the number average molecular weights (M_n) and polymer dispersity index (PDI) of telechelic oligomers. The structures of the oligomers were characterized using ¹H NMR, ¹³C NMR, and MALDI-TOF-MS, which confirmed the formation of the designed terminal groups. The results showed that well-defined telechelic oligomers with a M_n of a few thousand and a PDI around 1.6 were obtained, with potential applications in binder, lubricant and many other fields.     

Fe-Si-B非晶带材高温氧化行为及回收工艺

??In order to reduce the oxidative burning loss of Fe78Si9B13 amorphous ribbon in the recovery process?? the oxidation behavior of Fe78Si9B13 amorphous ribbon was studied. The results show that the oxidation of Fe78Si9B13 amorphous ribbon at high temperature is related to the heating rate. The oxidation weight gain of Fe78Si9B13 amorphous ribbon at 5 and 10K/min from room temperature to 1223K are 44% and 31% respectively. There is an oxide layer with loose texture and a small amount of microcrack at the interface between the sample and atmosphere by SEM. The oxide layer contains a large amount of Fe2O3 and a little SiO2 by XRD. Oxidation kinetics curve shows that the oxidation weight gain of the samples follows a linear rule within 5hours at 1073 and 1173K?? then a parabolic rule. At 1273K?? however?? it only follows a linear rule?? meanwhile the oxidation speed is very fast?? with the oxidation weight gain reaches 40% in 12min. The oxidation weight gain in the amorphous ribbon recycling process can be reduced through cutting down the furnace gas temperature?? compressing the waste ribbon and unqualified products in the packaging process and blowing argon to reduce the partial pressure of oxygen in the furnace. Thus the slag decreases to 9-10g when 1kg waste ribbon is recovered?? and the Si content of liquid alloy increases to 8. 9%.     

沿空切顶成巷段巷道围岩变形规律研究

以宏景塔一矿回采工作面为研究对象,基于切顶卸压无煤柱自动成巷技术原理,采用数值模拟计算和现场实测的方法,对该矿成巷段巷道围岩支承压力分布及围岩变形规律进行分析。研究结果表明:随着工作面向前推进,巷道围岩支承压力呈先增大后减小最后趋于稳定的变化趋势,支承压力稳定值为13.5 MPa;受工作面回采动压的影响,距离工作面70 m以内,锚索受力急剧增大到恒阻值、巷道围岩变形明显;距离工作面70~150 m,锚索受力迅速减小、巷道围岩变形逐渐变缓;在距离工作面150 m之后,锚索受力仅有微量变化、巷道围岩变形趋于稳定。因此确定支护体回撤保守安全位置为工作面后方150 m。工程实践表明:所设支护体回撤距离能够应对巷道围岩变形,成巷效果良好。