Dust and Particulate Matter Generated during Handling and Pelletization of Herbaceous Biomass: A Review

Recent advances in carbon-based materials derived from diverse green biowaste for sensing applications: a comprehensive overview from the perspective of synthesis method and application

The rapid increase in global waste, driven by population growth, has raised significant environmental concerns. Among different types of wastes, green biowastes (BWs) containing organic matter have attracted considerable attention. The conversion of BW, particularly from herbaceous and animal sources, to carbon-based materials (CBMs) introduces a suitable platform for waste management and resource recovery. Furthermore, this strategy creates valuable materials from low-value waste for various applications, sensing included. The abundance of these wastes provides a sustainable and affordable raw material and enhances the feasibility of fabricating these materials. Generally, the presence of carbon in their structure can present an accessible resource for producing different carbon materials, especially carbon dots (CDs), carbon quantum dots (CQDs), and graphene quantum dots (GQDs). The performance of these CBMs has been enhanced by optimizing synthesis processes, incorporating functional groups, and integrating various materials. The synthesized CBMs possess desirable features, such as biocompatibility, excellent physical, chemical, and electrical conductivity. These materials have been used in different sensors such as electrochemical (EC) and optical sensors for presenting high performance sensing probes with several benefits such as real-time monitoring, rapid detection, and high sensitivity. The first section of this review is dedicated to the preparation of CBMs, derived from green BWs, by different synthesized methods for use in different fields including biomedical application, food safety, and environmental monitoring. In addition, the challenges, limitations, and future directions in the development of these CBMs were completely discussed to improve their performance.

The effect of occupational exposure to organic dust on lung function parameters among African industrial workers: a systematic review and meta-analysis

Introduction

Inadequate ventilation and improper use of personal protective equipment are often observed in many occupational settings with a high risk of dust and other fine particle exposure. Workers who are exposed to dust at work may suffer from respiratory difficulties. Previous systematic reviews on organic dust exposure and its association with respiratory health outcomes did not provide a comprehensive assessment. Therefore, the objective of this systematic review and meta-analysis was to summarize the reported effects of organic dust exposure on lung function parameters among African industrial workers.

Methods

A compressive literature search was conducted in PubMed, MEDLINE, Google Scholar, Embase, the Web of Science, African Journals Online, and ScienceDirect databases to identify relevant studies for the review. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of the included studies. The lung function indices including forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), the FEV1/FVC ratio, and peak expiratory flow rate (PEFR) were obtained from primary studies and analyzed using STATA version 17. The I 2 test was used to assess the heterogeneity of studies. We used a random-effects model to estimate the pooled standard mean difference in lung function indices between organic dust-exposed and non-exposed industrial workers. To analyze publication bias, funnel plots and Egger's test were applied.

Results

In this systematic review and meta-analysis, 32 studies involving 7,085 participants were included from 13,529 identified studies. The estimated mean differences with 95% confidence intervals were as follows: -0.53 [-0.83 to -0.36] L for FVC, -0.60 [-0.77 to -0.43] L for FEV1, -0.43 [-0.57, -0.29] L for FEV1/FVC, and -0.69 [-0.88 to -0.50] L/min for PEFR.

Conclusion

This systematic review and meta-analysis revealed that the lung function indices, such as FVC, FEV1, FEV1/FVC, and PEFR, were statistically significantly lower among organic dust-exposed industrial workers compared to non-exposed industrial workers. Therefore, effective dust control measures should be implemented to protect workers from exposure to organic dust.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024527139.

Experimental Dust Absorption Study in Automotive Engine Inlet Air Filter Materials

The purpose of this study was to empirically evaluate the performance of fibrous materials that meet the criteria for inlet air filtration in internal combustion engines. The characteristics of filtration efficiency and accuracy, as well as the characteristics of flow resistance, were determined based on the mass of dust accumulated in the filter bed during the filtration process. Single-layer filter materials tested included cellulose, polyester, and glass microfiber. Multilayer filter media such as cellulose-polyester-nanofibers and cellulose-polyester were also examined. A new composite filter bed-consisting of polyester, glass microfiber, and cellulose-and its filtration characteristics were evaluated. Utilizing specific air filtration quality factors, it was demonstrated that the composite is characterized by high pre-filtration efficiency (99.98%), a short pre-filtration period (qs = 4.21%), high accuracy (dpmax = 1.5-3 µm) for the entire lifespan of the filter, and a 60-250% higher dust absorption coefficient compared to the other tested materials. A filtration composite bed constructed from a group of materials with different filtration parameters can be, due to its high filtration efficiency, accuracy, and dust absorption, an excellent filter material for engine intake air. The composite's filtration parameters will depend on the type of filter layers and their order relative to the aerosol flow. This paper presents a methodology for the selection and testing of various filter materials.

Sintering and Fusibility Risks of Pellet Ash from Different Sources at Different Combustion Temperatures

Pellets are solid biofuels with a combustion efficiency of 85–90%, low CO2 emissions and costs, great comfort and versatility. However, the ash generated during combustion can present sintering and fusibility, decreasing boiler efficiency and potentially malfunctioning. Ash composition indexes can be useful to predict observed ash sintering and fusion but require further analysis for a variety of feedstocks. The objective of this work was to determine the effect of the mineral composition of pellet ash from 15 biomasses of forest and agro-industrial sources on observed pellet ash slagging using a laboratory test. The chemical composition of pellets and the indexes B, NaK/B, SiP/CaMg and SiPNaK/CaMg at 550 and 1000 °C were determined. Pearson correlation tests were also performed between cumulative percentages of slag at different sieve sizes. The concentrations of CaO ranged from 4.49 to 65.95%, MgO varied from 1.99 to 17.61%, and the SiO2 concentration was between 16.11 and 28.24% and 2.19–56.75% at 550 and 1000 °C, respectively. Pellets of forest origin presented a low risk of slag formation, while those from agro-industrial sources showed a high risk of slag formation. The index SiPNaK/CaMg showed the highest correlation (R2 > 0.75) to observed slagging using the BioSlag test.

Experimental Investigation of Possibilities to Improve Filtration Efficiency of Tangential Inlet Return Cyclones by Modification of Their Design

It has been shown that tangential inlet return cyclones are commonly used for inlet air filtration of off-road vehicle engines. The wear of the engine elements, and thus their durability, is determined by the efficiency and accuracy of the inlet air filtration. It has been shown that the possibilities of increasing the separation efficiency or decreasing the pressure drop of a cyclone by changing the main dimensions of the cyclone are limited, because any arbitrary change in one of the dimensions of an already operating cyclone may cause the opposite effect. A literature analysis of the possibility of increasing the filtration efficiency of cyclones by modifying the design of selected cyclone components was conducted. In this paper, three modifications of the cyclone design with a tangential inlet of the inlet air filter of a military tracked vehicle were proposed and performed. The symmetrical inlet of the cyclone was replaced with an asymmetrical inlet. The cylindrical outlet tube was replaced with a conical tube, and the edges of the inlet opening were given an additional streamlined shape. The modification process was carried out on three specimens of the reversible cyclone with a tangential inlet. After each modification, an experimental evaluation of the modifications was carried out. The influence of the modifications on the cyclone’s efficiency characteristics and pressure drop was examined. Subsequent modifications of the cyclone were performed on the same specimen without removing the previous modifications. Tests were performed in the air flow range QG = 5–30 m3/h. Polydisperse “fine” test dust with grain size dpmax = 80 µm was used for testing. The dust concentration at the cyclone inlet was set at 1 g/m2. The performed modifications caused a slight (about 1%) increase in separation efficiency in the range of small (up to QG = 22 m3/h) flux values and about 30% decrease in pressure drop in the whole range of the QG flux, which positively influences the increase in engine filling and its power. There was a noticeable increase in filtration accuracy in the range of low and high values of QG flux, which results in a decrease in the wear of engine components, especially the piston-piston ring-cylinder (P-PR-C) association, and an increase in their durability.