Special Issue "Techniques for Sustainable Processing of Natural Resources II"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Environmental Sciences".

Deadline for manuscript submissions: closed (30 November 2020).

Special Issue Editors

Dr. María Ángeles Martín-Lara
E-Mail Website
Guest Editor
Department of Chemical Engineering, Faculty of Sciences, University of Granada, 18071 Granada, Spain
Interests: biomass gasification, pyrolysis, and torrefaction; adsorption of contaminants (mainly heavy metals) by porous solids; advances in mineral processing and management of mining waste; plastic waste management; life cycle assessment
Special Issues and Collections in MDPI journals
Prof. Dr. Mónica Calero de Hoces
E-Mail Website
Guest Editor
Department of Chemical Engineering, Faculty of Sciences, University of Granada, 18071 Granada, Spain
Interests: biomass gasification, pyrolysis, and torrefaction; adsorption of contaminants (mainly heavy metals) by porous solids; advances in mineral processing and management of mining waste; plastic waste management
Special Issues and Collections in MDPI journals
Prof. Dr. Gabriel Blázquez García
E-Mail Website
Guest Editor
Department of Chemical Engineering, Faculty of Sciences, University of Granada, 18071 Granada, Spain
Interests: biomass gasification, pyrolysis, and torrefaction; adsorption of contaminants (mainly heavy metals) by porous solids; advances in mineral processing and management of mining waste; plastic waste management
Special Issues and Collections in MDPI journals
Dr. Antonio Pérez Muñoz
E-Mail Website
Guest Editor
Department of Chemical Engineering, Faculty of Sciences, University of Granada, 18071 Granada, Spain
Interests: biomass gasification, pyrolysis, and torrefaction; adsorption of contaminants (mainly heavy metals) by porous solids; advances in mineral processing and management of mining waste; plastic waste management
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The 20th century era of seemingly plentiful and cheap resources is coming to an end. Reducing resource use and environmental impacts will require a decisive societal and technological transition to an economy based on a sustainable relationship between nature and human wellbeing. Innovation in these fields will provide opportunities for growth and jobs. The purpose of this Special Issue is to provide a forum for the rapid publication of topical papers featuring the latest developments in the allied fields of transformation processes of natural resources into energy and useful products. Its wide-ranging coverage of research and practical (operating) topics includes in situ processing, developing better separation processes, and finding better materials for use in energy and mineral applications, between others. There will be a focus on environmental issues, particularly those pertaining to sustainable development. For example, works about recycling, resource substitution, or life cycle assessment of resources to improve resource productivity are welcome.

Dr. María Ángeles Martín-Lara
Prof. Dr. Mónica Calero de Hoces
Prof. Dr. Gabriel Blázquez García
Dr. Antonio Pérez Muñoz
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • mineral processing
  • natural resources
  • recycling
  • resource substitution
  • separation processes

Published Papers (6 papers)

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Research

Article
Antimicrobial Air Filter Coating with Plant Extracts Against Airborne Microbes
Appl. Sci. 2020, 10(24), 9120; https://doi.org/10.3390/app10249120 - 20 Dec 2020
Viewed by 833
Abstract
Antimicrobial air filters are required to protect humans from the risk of secondary bioaerosol pollution as well as airborne particles. Three plant extracts (tea-tree oil, rosemary, and garlic) were selected to replace antimicrobial chemicals in air filters. The antimicrobial activity of plant extracts [...] Read more.
Antimicrobial air filters are required to protect humans from the risk of secondary bioaerosol pollution as well as airborne particles. Three plant extracts (tea-tree oil, rosemary, and garlic) were selected to replace antimicrobial chemicals in air filters. The antimicrobial activity of plant extracts was investigated using Micrococcus luteus and Escherichia coli. Phytochemicals present in the three plant extracts were identified using a gas chromatograph coupled with a mass spectrometer. The extracts were spray-coated on polyethylene terephthalate filter surfaces using silicate polymeric coating and evaluated via X-ray photoelectron spectroscopy and a scanning electron microscope with energy dispersive spectroscopy. After coating, an increase of 9.1% in the pressure drop was observed. The strain Micrococcus luteus was used to evaluate the antimicrobial activity of the air filter. After bioaerosol exposure, the tea-tree oil-coated filters immediately induced M. luteus cell inactivation (40–55%), whereas the rosemary and garlic coated filters did not. However, 48 h after exposure, a significant M. luteus inactivation of 99.99%, 99.0%, and 99.9% was recorded for concentrations of 2.89, 6.73, and 11.51 mg/cm2 for the tea-tree, rosemary, and garlic extracts, respectively. The coated filters exhibited high antimicrobial activity, thereby indicating significant potential for application as self-cleaning air filters. Full article
(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources II)
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Article
Formulation of Alkali-Activated Slag Binder Destined for Use in Developing Countries
Appl. Sci. 2020, 10(24), 9088; https://doi.org/10.3390/app10249088 - 18 Dec 2020
Cited by 1 | Viewed by 474
Abstract
Worldwide cement production is around 4.2 billion tons, and the fabrication of one ton of ordinary Portland cement emits around 900 kg of CO2. Blast furnace slag (BFS) is a byproduct used to produce alkali-activated materials (AAM). BFS production was estimated [...] Read more.
Worldwide cement production is around 4.2 billion tons, and the fabrication of one ton of ordinary Portland cement emits around 900 kg of CO2. Blast furnace slag (BFS) is a byproduct used to produce alkali-activated materials (AAM). BFS production was estimated at about 350 million tons in 2018, and the BFS reuse rate in construction materials of developing countries is low. AAM can reduce CO2 emissions in relation to Portland cement materials: Its use in construction would be a golden opportunity for developing countries in forthcoming decades. The present research aims to formulate AAM destined for future applications in developing countries. Two activators were used: NaOH, Na2CO3, and a mixture of both. The results showed that compressive strengths within the 42–56 MPa range after 28 curing days were obtained for the Na2CO3-activated mortars. The characterization analysis confirmed the presence of hydrotalcite, carbonated phases, CSH and CASH. The economic study showed that Na2CO3 was the cheapest activator in terms of the relative cost per ton and MPa of manufactured mortars. Finally, the environmental benefits of mortars based on this reagent were evidenced, and, in terms of kgCO2 emissions per ton and MPa, the mortars with Na2CO3 yielded 50% lower values than with NaOH. Full article
(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources II)
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Article
The Study of Economic and Environmental Viability of the Treatment of Organic Fraction of Municipal Solid Waste Using Monte Carlo Simulation
Appl. Sci. 2020, 10(24), 9028; https://doi.org/10.3390/app10249028 - 17 Dec 2020
Cited by 2 | Viewed by 552
Abstract
Valorization of municipal solid waste (MSW) plays a crucial role in a sustainable society and provides an opportunity to reduce carbon emissions. The economic and social viability of the treatment of the organic fraction of MSW (OFMSW) with a multi-scenario analysis (composting and [...] Read more.
Valorization of municipal solid waste (MSW) plays a crucial role in a sustainable society and provides an opportunity to reduce carbon emissions. The economic and social viability of the treatment of the organic fraction of MSW (OFMSW) with a multi-scenario analysis (composting and anaerobic digestion for renewable electricity or for biomethane injection into natural gas networks) was studied using a Monte Carlo simulation. The cost of treating organic fraction of MSW to neutralize financial net present value (NPV) and social NPV through greenhouse gas emissions avoided was determined for each scenario. The costs considered were the investment and the operating and maintenance costs. The financial benefits from the revenue of subproducts depended on the scenario. The lowest average fee to neutralize the financial NPV was 6.38 €/tonne treated in anaerobic digestion for biomethane injection into natural gas networks, therefore, it was the most financially viable. The average social NPV calculated for biomethane injection into natural gas networks (16.60 €/tonne) was higher than that obtained for renewable electricity (13.59 €/tonne). According to the results, anaerobic digestion for biomethane injection into natural gas networks is the most socially and economically viable alternative for the treatment of OFMSW. Full article
(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources II)
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Article
Xylitol Production from Exhausted Olive Pomace by Candida boidinii
Appl. Sci. 2020, 10(19), 6966; https://doi.org/10.3390/app10196966 - 05 Oct 2020
Cited by 5 | Viewed by 651
Abstract
In this work, the production of xylitol from a hemicellulosic hydrolysate of exhausted olive pomace (EOP), a residue originated in the olive oil production process by Candida boidinii, was assessed. The hydrolysate was obtained by dilute acid pretreatment of EOP at 170 [...] Read more.
In this work, the production of xylitol from a hemicellulosic hydrolysate of exhausted olive pomace (EOP), a residue originated in the olive oil production process by Candida boidinii, was assessed. The hydrolysate was obtained by dilute acid pretreatment of EOP at 170 °C and 2% H2SO4 (w/v). A previous detoxification step of the hydrolysate was necessary, and its treatment with activated charcoal and ion-exchange resin was evaluated. Prior to fermentation of the hydrolysate, fermentation tests in synthetic media were performed to determine the maximum xylitol yield and productivity that could be obtained if inhibitory compounds were not present in the medium. In addition, the glucose existing in the media exerted a negative influence on xylitol production. A maximum xylitol yield of 0.52 g/g could be achieved in absence of inhibitor compounds. Fermentation of the hemicellulosic hydrolysate from EOP after detoxification with ion-exchange resin resulted in a xylitol yield of 0.43 g/g. Full article
(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources II)
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Article
Predicting the Pillar Stability of Underground Mines with Random Trees and C4.5 Decision Trees
Appl. Sci. 2020, 10(18), 6486; https://doi.org/10.3390/app10186486 - 17 Sep 2020
Cited by 3 | Viewed by 780
Abstract
Predicting pillar stability in underground mines is a critical problem because the instability of the pillar can cause large-scale collapse hazards. To predict the pillar stability for underground coal and stone mines, two new models (random tree and C4.5 decision tree algorithms) are [...] Read more.
Predicting pillar stability in underground mines is a critical problem because the instability of the pillar can cause large-scale collapse hazards. To predict the pillar stability for underground coal and stone mines, two new models (random tree and C4.5 decision tree algorithms) are proposed in this paper. Pillar stability depends on the parameters: width of the pillar (W), height of the pillar (H), W/H ratio, uniaxial compressive strength of the rock (σucs), and pillar stress (σp). These parameters are taken as input variables, while underground mines pillar stability as output. Various performance indices, i.e., accuracy, precision, recall, F-measure, Matthews correlation coefficient (MCC) were used to evaluate the performance of the models. The performance evaluation of the established models showed that both models were able to predict pillar stability with reasonable accuracy. Results of the random tree and C4.5 decision tree were also compared with available models of support vector machine (SVM) and fishery discriminant analysis (FDA). The results show that the proposed random tree provides a reliable and feasible method of evaluating the pillar stability for underground mines. Full article
(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources II)
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Article
Comparison Between Performance of Fluorite Flotation Under Different Depressants Reagents in Two Pieces of Laboratory Equipment
Appl. Sci. 2020, 10(16), 5667; https://doi.org/10.3390/app10165667 - 15 Aug 2020
Cited by 1 | Viewed by 565
Abstract
Fluorite is an important industrial mineral composed of calcium and fluorine (CaF2). This mineral is widely distributed through different deposits. However, in most cases, fluorite is tightly associated with gangue, such as calcite and quartz. In this paper, different depressants are [...] Read more.
Fluorite is an important industrial mineral composed of calcium and fluorine (CaF2). This mineral is widely distributed through different deposits. However, in most cases, fluorite is tightly associated with gangue, such as calcite and quartz. In this paper, different depressants are tested in the flotation of fluorite in two different laboratory configurations—cell and column. Quebracho tree (QT) was tested as the main depressant in combination with white dextrin (WD), potato starch (PT), carboxymethyl cellulose (CMC), and sodium hexametaphosphate (SHMP). The optimum pulp pH of the flotation of fluorite was determined as approximately 9.5–10. The best results are obtained using a combination of quebracho and white dextrin as depressants, reaching 74% of fluorite grade for modified column flotation and 70.5% for cell flotation. Additionally, the metallurgical recovery obtained higher values when the flotation was carried out in the modified column and using the same combination of depressant agents—75% for modified column flotation and 60% for flotation cell. Full article
(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources II)
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