2025, Volume 71(75), Issue 1 (March)

Contents

pages 1- 8   Download  

Layered Double Hydroxides: Insights Into the Structural Regeneration by Memory Effect

DENIS CUTCOVSCHI, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
SOFRONIA BOUARIU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
GABRIELA CARJA, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania, gabriela.carja@academic.tuiasi.ro

pages 9 - 22   Download
DOI: 10.5281/zenodo.15062732
Abstract
Layered double hydroxides (LDHs) are a unique class of inorganic compounds, presenting positively charged layers arranged in a brucite-like structure. These materials are highly versatile due to their ability to host various anions in the interlayer spaces and accommodate diverse cations in the layers. As a result, LDHs have broad applications in fields like drug delivery, water purification, and catalysis. A key characteristic of LDHs is their structural “memory effect,” which allows them to restore their original structure after calcination. Factors such as temperature, pressure, pH, and the specific anions and cations involved significantly affect the properties of LDHs during regeneration. This work provides an in-depth review of the properties and uses of LDHs regenerated through the memory effect, offering insights into how their physical-chemical features can be tailored.
Keywords: Layered double hydroxide, mixed oxides, structural recovery, memory effect

Fly Ash-Geopolymer Foam Activated in Alkaline Environment Based on Potassium

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

pages 23 - 35   Download
DOI: 10.5281/zenodo.15062734
Abstract
Fly ash-geopolymer foam was made under the conditions of choosing an alkaline activator solution composed of potassium hydroxide and potassium silicate compared to the sodium-based ones usually used. The adopted expanding agent was sodium perborate substituting the known hydrogen peroxide (H2O2), silica fume was chosen due to its ability for increasing the foam strength, and olive oil was the agreed surfactant replacing more effective but more expensive materials. The results showed porous products with excellent heat-insulating properties and simultaneously satisfactory compression and flexural resistance obtained at an early age (7 days) the quality level being almost similar to that of the best products worldwide.
Keywords: fly ash, geopolymer foam, sodium perborate, silica fume, heat-insulating properties

Study On Obtaining Oily Extract from Linden Flowers and Using It in A Cold Cream

CLAUDIA COBZARU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
MAGDALENA ALUPOAE, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
GABRIELA-ANTOANETA APOSTOLESCU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
MĂLINA-MARIA CERNĂTESCU, “Grigore T. Popa” University of Medicine and Pharmacy Iași, Iași, Romania
CORINA CERNĂTESCU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania, corina.cernatescu@academic.tuiasi.ro

pages 37 - 46   Download
DOI: 10.5281/zenodo.15062815
Abstract
The extract of linden flowers was obtained by maceration in sunflower oil and, then, the extract was incorporated into a cold cream. The photodegradation, TGA-DTGA analyses as well as the iodine, acidity and saponification index, performed on the oily extract showed that it contains active plant compounds that can contribute to its long-term use. The cosmetic cream obtained with the oily extract of linden flowers demonstrated that, from a qualitative point of view, it is moisturizing and nourishing, beneficial for the skin but with a short shelf life (6 weeks).
Keywords: oily maceration, linden flowers, cold cream, photodegradation    

An Unconventional Asphalt. Some Characteristics of Steel Slag Asphalt

ANDREEA MONORANU, “Gheorghe Asachi” Technical University of Iași, Faculty of Civil Engineering, Iași, Romania, andreea.monoranu@student.tuiasi.ro
GHEORGHE GUGIUMAN, “Gheorghe Asachi” Technical University of Iași, Faculty of Civil Engineering, Iași, Romania
SILVIU CRISTIAN IRICIUC, “Gheorghe Asachi” Technical University of Iași, Faculty of Civil Engineering, Iași, Romania
GELU-RĂZVAN GIMIGA, “Gheorghe Asachi” Technical University of Iași, Faculty of Civil Engineering, Iași, Romania

pages 47 - 60   Download
DOI: 10.5281/zenodo.15062817
Abstract
It has been known since ancient times that a good infrastructure is needed to develop an area. But because there are more and more areas in continuous development, raw materials are consumed with acceleration and the planet is becoming progressively occupied by waste, we are trying to find other materials than the classic ones to use in road construction. Ordinary asphalt mixtures have aggregates of different grades, filler and bitumen in their composition. If normally the aggregates used for the production of asphalt are extracted from nature, in this study we showed how we produced an asphalt with aggregates from crushed steel slag, an industrial waste, obtained after the manufacture of steel. Inside the article you will discover the establishment of recipes for asphalt mixtures with crushed steel slag, the making of samples and their testing according to the norms in force. The results obtained are encouraging, some characteristics of this asphalt being better than the asphalt prepared with classic aggregates. The use of crushed steel slag in areas where there are dumps with this waste could generate a double benefit: the release of some storage spaces and the production of a cheaper asphalt.
Keywords: steel slag, asphalt mixture, recycle, waste  

Chemical Method of Biomass Delignification as An Advanced Technique for Preparing Wood Foam with Insulating Properties

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

pages 61 - 74   Download
DOI: 10.5281/zenodo.15062944
Abstract
The paper refers to a method of lignin removing in the biomass structure to obtain a wooden material with excellent heat-insulating properties suitable for use as an insulating material in construction. In principle, the method is almost similar to that applied in the pulp and paper industry, but with a different technological purpose. The chemical activation of maple wood waste was obtained through contact with an aqueous alkaline environment containing NaOH and Ca(OH)2 the effect being significant reduction of thermal conductivity compared to non-chemically treated wood. The originality is the use for the first time of maple wood as recycled sawdust. The process temperature was 90° C for 8 hours. Results were remarkable, the optimal product having density of 0.21 g·cm-3 and heat conductivity of 0.029 W·m-1·K-1. In quality terms, the delignified wood features were almost similar with other foamed wooden products.
Keywords: maple wood, removing lignin, biomass, alkaline environment, thermal conductivity  

Bioremediation in Circular Economy: Case Study of Cu(II) Removal via Lignin-Based Biomass

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

pages 75 - 84   Download
DOI: 10.5281/zenodo.15062946
Abstract
In the context of sustainable development, the present study proposes a novel approach to minimise the harmful effects of pollutant sources, such as heavy metal ions, and to effectively utilise bioresources in the same time. The study proposes the retention of Cu(II) ions in static conditions using Sarkanda grass lignin, a biomass residue, representing a renewable natural resource and a versatile biomaterial. This complex compound demonstrates thermodynamic, and biological efficiency. The experimental data obtained suggest potential applications in the treatment of wastewater, offering a sustainable alternative to the already established, but more expensive, technologies. This research supports the expansion of the use of biomaterials for environmental remediation, highlighting the importance of minimising waste and conserving natural resources in support of a circular bioeconomy. Future research will focus on optimizing the retention process, evaluating the long-term stability of the material, and exploring the scalability of this technology for industrial wastewater treatment.
Keywords: bioremediation, lignin, Cu(II) ions, retention, Lypercosium esculentum, circular bioeconomy  

Use of PET Fibers – Polyethylene Terephtalate (Plastic Bottles) in the Composition of Asphalt Mixture Type BADPC 22.4

CLAUDIU-IONEL CHICUȘ, “Gheorghe Asachi” Technical University of Iași, Faculty of Civil Engineering and Building Services, Iași, Romania, claudiu-ionel.chicus@student.tuiasi.ro
GHEORGHE GUGIUMAN, “Gheorghe Asachi” Technical University of Iași, Faculty of Civil Engineering and Building Services, Iași, Romania
SILVIU CRISTIAN IRICIUC, “Gheorghe Asachi” Technical University of Iași, Faculty of Civil Engineering and Building Services, Iași, Romania
GELU-RĂZVAN GIMIGA, “Gheorghe Asachi” Technical University of Iași, Faculty of Civil Engineering and Building Services, Iași, Romania

pages 85 - 100   Download
DOI: 10.5281/zenodo.15063017
Abstract
The use of plastic waste in construction represents an innovative solution for reducing the environmental impact of these materials. One of the most commonly recycled plastic types in construction is polyethylene terephthalate (PET), due to its durability, lightweight nature, and availability. In the construction industry, plastic waste and PET are incorporated either into cement concrete or asphalt mixtures, contributing to improved mechanical performance and the sustainability of these materials. In cement concrete, the addition of PET fibers can enhance crack resistance, durability, and flexibility while also reducing the need for conventional materials. In the case of asphalt mixtures, PET is used in the form of fibers or recycled aggregates, playing a role in enhancing road performance and extending their service life. In this study, experiments were conducted on the BADPC 22.4 asphalt mixture. In the first stage, the optimal bitumen content was determined, and for this content, the asphalt mixture was reinforced with PET fibers in proportions of 2%, 4%, 6%, 8%, and 10% to analyze their influence on the material's physical and mechanical properties.
Keywords: laboratory studies, binder, roads, PET

Physico-Chemical Characteristics of Some Ecological Products Used for Textile Care

VALENTINA GABI MIRON (STĂNESCU), “Gheorghe Asachi” Technical University of Iași, Faculty of Industrial Design and Business Management, Iași, Romania
NIKI VLAD MANCAȘI, “Gheorghe Asachi” Technical University of Iași, Faculty of Industrial Design and Business Management, Iași, Romania
VASILICA POPESCU, “Gheorghe Asachi” Technical University of Iași, Faculty of Industrial Design and Business Management, Iași, Romania, vasilica.popescu@academic.tuiasi.ro
ANDREI POPESCU, “Gheorghe Asachi” Technical University of Iași, Faculty of Industrial Design and Business Management, Iași, Romania; “Gheorghe Asachi” Technical University of Iași, Faculty of Mechanical Engineering, Iași, Romania

pages 101 - 112   Download
DOI: 10.5281/zenodo.15063019
Abstract
Protecting the environment is an international issue that depends a lot on the involvement of each of us through actions to collect and recycle different used products. The purpose of this paper is to show that used cooking oils should be collected to be transformed into ecological laundry care products: soaps. The laundry soaps prepared by us were obtained through hot saponification processes, using the mixture of palm and coconut oils, unused and used/waste, in all 4 possible combinations. The characterization of the vegetable oils was carried out by determining the saponification value (SAP) and the iodine number (IN). The obtained soaps were characterized physically and chemically by determining pH, foam, color, density, cleaning/washing capacity inclusive the SAP, IN, INS (Iodine Number Saponification) values for oils mixture from soaps. The tested ecological soaps are excellent products for washing clothes because each has a low foaming and an excellent cleaning capacity.
KeKeywords: laundry soaps, palm oil, coconut oil, recycling, cleaning capacity