Production and characterization of polyethylene terephthalate nanoparticles

Microplastic (MP) pollution represents one of the biggest environmental problems that is further exacerbated by the continuous degradation in the marine environment of MPs to nanoplastics (NPs). The most diffuse plastics in oceans are commodity polymers, mainly thermoplastics widely used for packaging, such as polyethylene terephthalate (PET). However, the huge interest in the chemical vector role of micro/nanoplastics, their fate and negative effects on the environment and human health is still under discussion and the research is still sparse due also to the difficulties of sampling MPs and NPs from the environment or producing NPs in laboratory. Moreover, the research on MPs and NPs pollution relies on the availability of engineered nanoparticles similar to those present in the marine environment for toxicological, transport and adsorption studies in biological tissues as well as for wastewater remediation studies. This work aims to develop an easy, fast and scalable procedure for the production of representative model nanoplastics from PET pellets. The proposed method, based on a simple and economic milling process, has been optimized considering the peculiarities of the polymer. The results demonstrated the reliability of the method for preparing particle suspensions for aquatic microplastic research, with evident advantages compared to the present literature procedures, such as low cost, the absence of liquid nitrogen, the short production time, the high yield of the process, stability, reproducibility and polydisperse size distribution of the produced water dispersed nanometric PET

Selective Disintegration–Milling to Obtain Metal-Rich Particle Fractions from E-Waste

This research was supported by ERDF project no. 1.1.1.1/20/A/139 “Development of sustainable recycling technology of electronic scrap for precious and non-ferrous metals extraction”. The project was co-financed by REACT-EU funding to mitigate the effects of the pandemic crisis. The article was published with the financial support from the Riga Technical University Research Support Fund. This research was also supported by the Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2. The authors would also like to mention the support from the “Innovation Grants for Maritime Students” performed at Latvian Maritime Academy (project no: 1.1.1.3/18/A/006, funded by the European Regional Development Fund—ERDF, Republic of Latvia).Various metals and semiconductors containing printed circuit boards (PCBs) are abundant in any electronic device equipped with controlling and computing features. These devices inevitably constitute e-waste after the end of service life. The typical construction of PCBs includes mechanically and chemically resistive materials, which significantly reduce the reaction rate or even avoid accessing chemical reagents (dissolvents) to target metals. Additionally, the presence of relatively reactive polymers and compounds from PCBs requires high energy consumption and reactive supply due to the formation of undesirable and sometimes environmentally hazardous reaction products. Preliminarily milling PCBs into powder is a promising method for increasing the reaction rate and avoiding liquid and gaseous emissions. Unfortunately, current state-of-the-art milling methods also lead to the presence of significantly more reactive polymers still adhered to milled target metal particles. This paper aims to find a novel and double-step disintegration–milling approach that can provide the formation of metal-rich particle size fractions. The morphology, particle fraction sizes, bulk density, and metal content in produced particles were measured and compared. Research results show the highest bulk density (up to 6.8 g·cm−3) and total metal content (up to 95.2 wt.%) in finest sieved fractions after the one-step milling of PCBs. Therefore, about half of the tested metallic element concentrations are higher in the one-step milled specimen and with lower adhered plastics concentrations than in double-step milled samples. © 2022 by the authors.--//-- This is an open access article Blumbergs E., Serga V., Shishkin A., Goljandin D., Shishko A., Zemcenkovs V., Markus K., Baronins J., Pankratov V. "Selective Disintegration–Milling to Obtain Metal-Rich Particle Fractions from E-Waste" (2022) Metals, 12 (9), art. no. 1468, DOI: 10.3390/met12091468 published under the CC BY 4.0 licence.Latvian Maritime Academy (project no: 1.1.1.3/18/A/006); ERDF project no. 1.1.1.1/20/A/139; REACT-EU; Institute of Solid-State Physics, University of Latvia has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase 2 under grant agreement No. 739508, project CAMART2

Development of a regenerative pump impeller using rapid manufacturing techniques

This paper presents a method of rapid manufacture used in the development of a regenerative pump impeller. Rapid manufacturing technology was used to create complex impeller blade profiles for testing as part of a regenerative pump optimisation process. Regenerative pumps are the subject of increased interest in industry. Ten modified impeller blade profiles, relative to the standard radial configuration, were evaluated with the use of computational fluid dynamics and experimental testing. Prototype impellers were needed for experimental validation of the CFD results. The manufacture of the complex blade profiles, using conventional milling techniques, is a considerable challenge for skilled machinists. The complexity of the modified blade profiles would normally necessitate the use of expensive CNC machining with 5 asis capability. With an impeller less than 75mm in diameter and a maximum blade thickness of 1.3mm, a rapid manufacturing technique enabled production of complex blade profiles that were dimensionally accurate and structurally robust enough for testing. As more advanced rapid prototyping machines become available in the study in the future, e.g. 3D photopolymer jetting machine, the quality of the parts, particularly in terms of surface finish, will improve and the amount of post processing operations will reduce. This technique offers the possibility to produce components of increased complexity whilst ensuring quality, strength, performance and speed of manufacture. The ability to manufacture complex blade profiles that are robust enough for testing, in a rapid and cost effective manner is proving essential in the overall design optimisation process for the pump

Стійка технологія переробки відходів електричного та електронного обладнання

Об’єкт досліджень: технологічні основи «переробки відходів електричного та електронного обладнання». Предмет досліджень: механізм піролізу, отримання рідкого палива, подрібнення друкованих плат після піролізу, вібраційний млин та його сили, які впливають на подрібнення. Вихідні дані для проведення роботи: характеристики друкованих плат та їх переробка у світі. Наукова новизна: відокремлення металевої фракції від наповнювачів, за рахунок ковкості металевої фракції при подрібнені та подальшому розділення при грохочені. Практична цінність: поліпшення екологічної складової за рахунок втілення нових технологій в сектор управління відходів та рециклінгу вже добутих мінералів. Дипломна робота написана англійською мовою та надалі буде захищена в ТУ "Фрайберзька гірнича академія"

Ultrasonic Production of Nano-Size Dispersions and Emulsions

Ultrasound is a well-established method for particle size reduction in dispersions and emulsions. Ultrasonic processors are used in the generation of nano-size material slurries, dispersions and emulsions because of the potential in the deagglomeration and the reduction of primaries. These are the mechanical effects of ultrasonic cavitation. Ultrasound can also be used to influence chemical reactions by the cavitation energy. This is sonochemistry. As the market for nano-size materials grows, the demand for ultrasonic processes at production level increases. At this stage, energy efficiency becomes important. Since the energy required per weight or volume of processed material links directly to the equipment size required, optimization of the process efficiency is essential to reduce investment and operational costs. Furthermore it is required to scale the lab and bench top configurations to this final level without any variations in the process achievements. Scale up by power alone will not do this.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Effects of different mechanical treatments on structural changes of lignocellulosic waste biomass and subsequent Cu(II) removal kinetics

In this paper, the character of structural changes induced by different mechanical treatments to Prunus persica stones (PSs), and its subsequent effect on biosorption kinetics of Cu(II) were investigated. PSs were processed in vibratory disk mill (PS-V) and ultra-centrifugal mill (PS-C) and characterized by XRD, BET, SEM and FTIR spectroscopy. It was shown that PS-V was smaller and more reactive with less crystallinity index and hydrogen bond intensity compared to PS-C. In opposite, surface area of the PS-C was bigger than that of the PS-V. The total pore volume was about threefold, while the volume of micro pores was 9.29 times higher in PS-Cs than in PS-Vs. The kinetics of Cu(II) biosorption by both PSs was tested through various kinetic models: pseudo-first and pseudo-second order rate equations, Elovich equation, Boyd model, Weber–Morris and Urano–Tachikawa intraparticle diffusion model. For both sample types, Cu(II) biosorption occurred through combination of intraparticle and film diffusion mechanism, while kinetic results were best described by the pseudo-second order kinetic model. At the same time, the results indicated that together with kinetic rate the biosorption capacity of PS-C (21.20 mg g−1) was higher than that of PS-V (16.30 mg g−1). Mechanical activation like crushing and grinding will change material particle size, specific surface area and porosity, as well as its crystallinity. However, this paper elucidates that such physical structural changes will impact on heavy metal ions removal efficiency. This investigation suggests that the type of size reduction in lignocellulosic biosorbent preparation plays a very important role in overall biosorption performance, so it should be carefully considered every time when the mechanical treatment of material is necessary to be applied

Recovering the lost gold of the developing world : bibliographic database

This report contains a library of 181 references, including abstracts, prepared for Project R 7120 "Recovering the lost gold of the developing world" funded by the UK' s Department for International Development (DFID) under the Knowledge and Research (KAR) programme. As part of an initial desk study, a literature review of gold processing methods used by small-scale miners was carried out using the following sources; the lSI Science Citation Index accessed via Bath Information and Data Services (BIDS), a licensed GEOREF CD-ROM database held at the BGS's Library in Keyworth and IMMage a CD-ROM database produced by the Institution of Mining and Metallurgy held by the Minerals group ofBGS. Information on the search terms used is available from the author

Size reduction of polymeric particulates by jet milling

A basic theory for the size reduction operation by jet milling has been developed. Typical samples of feedstock have been analyzed using screen analysis to determine the initial distribution of polymeric particulate sizes prior to jet milling. A statistical theory .was developed using probabilities to represent the likelihood that specific size reductions would occur. These probabilities include the effects of various equipment. The theory was then used to predict the distribution of polymeric particulate sizes after jet milling. The agreement between the predictions and actual results was within 5 %. Encouraged by the successful work of the simulation of the process, the simulation for the energy consumed will be expected. By finishing the energy portion, screen analysis-operation-energy unit will comprise a core unit in the Computer Integrated Manufacturing (C114)

Synthesis and Characterisation of Bio-based Epoxy/Clay Nanocomposites

The thesis focuses on investigating the substitution of conventional epoxy with a bio-based epoxy constituent to achieve bionanocomposites with sustainable bio-based content and optimal mechanical properties. Taguchi design of experiments was employed to determine the preferred combination of factors in manufacturing bionanocomposites. Mechanical, thermal and biodegradability properties, as well as morphological structure were observed to investigate the effect of clay and bio-based content. Theoretical models were studied in successfully predicting mechanical properties of bioepoxy/clay nanocomposites

The Sustainable Composite Materials in Civil and Architectural Engineering

This book is a collection of 10 research articles (from 18 submissions) authored by researchers and peer reviewed by professionals in the field to address the use of sustainable composite materials in civil and architectural engineering over the course of more than 2 years. Fiber-reinforced plastic (FRP), geopolymers, and various recycled and repurposed waste materials are among the items addressed, used in a variety of applications from flame retardance to energy consumption. This book is a great resource for both academics and professionals in the field of engineering