2024, Volume 70(74), Issue 3 (September)

Contents

pages 1- 8   Download

Geopolymer Composite Made for High Temperature Applications

LUCIAN PĂUNESCU, Daily Sourcing & Research SRL Bucharest, Romania, lucianpaunescu16@gmail.com
BOGDAN VALENTIN PĂUNESCU, Consitrans SA Bucharest, Romania
ENIKÖ VOLCEANOV, National University of Science and Technology “Politehnica” Bucharest,  Faculty of Engineering in Foreign Language, Bucharest, Romania, Metallurgical Research Institute SA Bucharest, Romania

pages 9 - 21   Download
DOI: 10.5281/zenodo.13837708
Abstract
Geopolymer composite for high temperature applications was made using masonry rubble waste resulting from building demolition (clay brick scraps and concrete scraps). It was known that the geopolymer has an initial fire resistance due to the inorganic network constituting its structure, but the concern for testing and improving the mechanical strength of this new material type exposed to high temperatures was not a research objective until recently. Geopolymer manufacturing included traditional by-products such as granulated metallurgical slag (predominantly) and fly ash as alumina-silicate materials with cementitious properties as well as the alkaline activator, in which NaOH was replaced with KOH due to its superior thermal resistance. Results showed that compressive strength recorded acceptable losses up to 800°C and higher at 1000°C, while flexural strength increased at 600 and 800°C compared to reference value and then decreased after heating to 1000°C.
Keywords: geopolymer composite, granulated slag, fly ash, clay brick, demolition waste.

Phytochemical Screening of Sida Rhombifolia Knitting Extract Macerated with Aloe Vera Gel to Combat Mosquito Attacks

DYDIMUS EFEZE NKEMAJA, University of Bamenda, Bambili, Cameroon
SERGE ENAMA ETEME, University of Yaoundé 1, Laboratory of Parasitology and Ecology, Department of Animal Biology and Physiology, Faculty of Sciences, Cameroon
ABDOURAMANE NSANGOU, University of Douala, Mechanical Laboratory (LME), ENSET Douala, Cameroon, University of Douala, Mechanics Laboratory, Research Group on Innovative Materials (GRMI), Cameroon
FABIEN EBANDA BETENE, University of Douala, Mechanical Laboratory (LME), ENSET Douala, Cameroon, University of Douala, Mechanics Laboratory, Research Group on Innovative Materials (GRMI), Cameroon
DOINA SIBIESCU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania, doina.sibiescu@academic.tuiasi.ro
PIERRE MARCEL ANICET NOAH, University of Douala, Mechanical Laboratory (LME), ENSET Douala, Cameroon, University of Douala, Mechanics Laboratory, Research Group on Innovative Materials (GRMI), Cameroon
ACHILLE DÉSIRÉ BETENÉ OMGBA, University of Douala, Mechanical Laboratory (LME), ENSET Douala, Cameroon, University of Douala, Mechanics Laboratory, Research Group on Innovative Materials (GRMI), Cameroon
VALERY HAMBATÉ GOMDJÉ, Departments of Textile and Leather Engineering, ENSPM, University of Maroua, Cameroon    

pages 23 - 33   Download
DOI: 10.5281/zenodo.13837762
Abstract
The objective of this study is to identify the metabolites in the extract of Sida rhombifolia fibers treated with Aloe vera gel using colored reactions and thin-layer chromatography, following analytical techniques. The results show that the three samples fibers not treated with Aloe vera gel, fibers treated with Aloe vera gel, and washed treated fibers contain flavonoids in low quantities. The first two samples also present sterols and triterpenes in medium quantities, while the washed treated fibers contain these in low quantities. Based on the chromatographic profiles, it can be concluded that the untreated fibers, treated fibers, and washed treated fibers extracts have nearly identical constituents, as the Rf values of the different spots are the same. The UV light absorption profile indicates the presence of chromophores responsible for this absorption, specifically double and triple bonds, which are also confirmed by fluorescence (π-π* transition). The different colors observed include yellow for flavonoids, blue for triterpenes, black for alkaloids, and orange for sterols. Looking ahead, the experiments recommended by the World Health Organization (WHO) on the effectiveness of impregnated curtains in combating mosquito attacks (cone test, cylinder test, and tunnel test) will be the focus of future work.
Keywords: Knitting, phytochemical, screening, Sida rhombifolia

Upcycling in Fashion – A Literature Review

LAVINIA MARIA POPA, “Gheorghe Asachi” Technical University of Iași, Faculty of Industrial Design and Business Management, Iași, Romania, lavinia-maria.popa@student.tuiasi.ro
ANTONELA CURTEZA, “Gheorghe Asachi” Technical University of Iași, Faculty of Industrial Design and Business Management, Iași, Romania  

pages 35 - 46   Download
DOI: 10.5281/zenodo.13837849
Abstract
The concept of upcycling is an integral part of modern fashion. It involves reusing clothing products that are no longer useful or have reached the end of their life cycle by converting them into new, value-added products. Because of its potential to improve environmental efficiency, the concept has attracted widespread attention from business and academic communities. This study highlights how academic research has been conducted on this topic. The methodology was developed through a systematic literature review and data analysis from the last ten years. The study explored the distribution of papers through different approaches (year, country, authors, methodology). This study will help academics and researchers expand the scientific literature's scope. As a result, 102 papers were obtained from various sources such as conferences and journals. The scope of this paper is to review the literature on this topic and to examine how it is disseminated in the digital age.
Keywords: sustainability, review, reuse, circular economy, redesign.

Advanced Wood Foam Production Technique as An Alternative Heat-Insulating Material for Building Construction

LUCIAN PĂUNESCU, Daily Sourcing & Research SRL Bucharest, Romania, lucianpaunescu16@gmail.com
ENIKÖ VOLCEANOV, National University of Science and Technology “Politehnica” Bucharest,  Faculty of Engineering in Foreign Language Bucharest, Romania, Metallurgical Research Institute SA Bucharest, Romania  

pages 47 - 56   Download
DOI: 10.5281/zenodo.13837887
Abstract
 The paper has tested an alternative heat-insulating material for building construction based on wood foaming. The wood waste chosen for this test was oak wood not used in other previous experiments presented in the literature. The purpose of the work is to replace the plastics currently used for the production of heat-insulating materials. Using ground wood waste, a suitable surfactant (sodium dodecyl sulfate), and distilled water, wet suspension was prepared, foamed by stirring and then dried at 80°C. Thus, it was obtained an optimal specimen with excellent heat-insulating properties (apparent density of 0.014 g·cm-3, heat conductivity of 0.035 W·m-1·K-1). The compressive strength had a rather low value of 715 kPa, but satisfactory for the intended purpose. By comparison with other experimentally prepared wood foams, the oak wood foam properties fell within the performance required by the use of the new material as a thermal insulator in construction, being able to replace similar polymer-based materials.
Keywords: wood foam, oak wood, surfactant, heat-insulating property, heat conductivity.

Lignin-Based Biomass Fractions for Cr(VI) Adsorption from Aqueous Media – Thermodynamic, Spectral and Biological Analysis  

ELENA UNGUREANU, “Ion Ionescu de la Brad” Iași University of Life Sciences, Iași, Romania  
BOGDAN-MARIAN TOFĂNICĂ, “Gheorghe Asachi” Technical University of Iași, Iași, Romania, b.m.tofanica@gmail.com
OVIDIU C. UNGUREANU, “Vasile Goldiș” West University of Arad, Arad, Romania
MARIA-EMILIANA FORTUNĂ, “Petru Poni” Institute of Macromolecular Chemistry, Iași, Romania
IRINA VOLF, “Gheorghe Asachi” Technical University of Iași, Iași, Romania
VALENTIN I. POPA, “Gheorghe Asachi” Technical University of Iași, Iași, Romania  

pages 57 - 64   Download
DOI: 10.5281/zenodo.13837919
Abstract
In the context of the complex valorisation of biomass and the absolute need to mitigate polluting sources, such as heavy metals, the present study proposes a renewable/strategic bioresource, Sarkanda grass (Tripidium bengalense) lignin, as a substrate for adsorption of the Cr(VI) ions from aqueous media under static conditions. Through a synthesis of thermodynamic, spectral, and biological considerations, the study demonstrates the efficacy of this natural aromatic polymer. The findings suggest potential applications in industrial wastewater treatment, offering a sustainable alternative to existing methods. This research contributes to the growing field of bio-based materials for environmental remediation, highlighting the value of agricultural waste in addressing water pollution challenges.
Keywords: Sarkanda grass lignin, Tripidium bengalense, Cr(VI) ions, adsorption, Triticum aestivum L

Management of Packaging Waste from E-Commerce in the Context of the Circular Economy

CONSTANTIN CÎRJAN, “Gheorghe Asachi” Technical University of Iasi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Department of Environmental Engineering and Management, Romania
DANIELA GAVRILESCU, “Gheorghe Asachi” Technical University of Iasi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Department of Environmental Engineering and Management, Romania, daniela.gavrilescu@academic.tuiasi.ro
CARMEN TEODOSIU, “Gheorghe Asachi” Technical University of Iasi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Department of Environmental Engineering and Management, Romania

pages 65 - 77   Download
DOI: 10.5281/zenodo.13837961
Abstract
Sustainability in e-commerce is a new but significant issue in the context of European Union's transition to a circular economy due to the rapidly growing e-commerce market. In Romania, over 500,000 single-use plastic or cardboard packaging materials are used daily for online shipments. The packaging sector is one of the major consumers of virgin raw materials. The increased use of packaging, combined with low rates of reuse and recycling, hinders the development of a circular economy. In recent years, the packaging industry has grown faster than the national gross income of various countries, leading to increased CO2 emissions and other pollutants, as well as overexploitation of natural resources, loss of biodiversity, and pollution. To minimize the negative impact, efforts are currently underway to develop and implement more sustainable practices in the online commerce industry, including the use of recyclable packaging, optimizing transportation, and promoting ecological practices. Consumers can also play a crucial role by carefully choosing products and merchants with environmental concerns and by adopting more responsible purchasing practices. In this context the main objective of this study is to analyse the management of packaging waste generated by e-commerce within the framework of circular economy. The most important practices and trends at international and national level are discussed and recommendations regarding the management of packaging waste resulted from electronic commerce in Romania are provided.
Keywords: e-commerce, circular economy, packaging waste, sustainability.