Mohamed Farouk Mhenni

Mechanical and thermal properties of Posidonia oceanica cellulose nanocrystal reinforced polymer

In the present study, cellulose nanocrystals (CNC) were isolated from Posidonia oceanica balls and leaves. CNC was prepared from this marine biomass by sulfuric acid hydrolysis (H2SO4) treatment. The raw fibers were firstly isolated by a delignification-bleaching process then the acid hydrolysis treatment was performed at 55°C during 40min under mechanical stirring. The ensuing CNCs were characterized by their morphological and thermal properties using transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA), respectively. Nanocomposite materials using the CNC extracted from marine biomass were obtained by casting and evaporating a mixture of this suspension with poly(styrene-co-butyl acrylate). The effect of CNC loading on mechanical and thermal properties was studied. Dynamic mechanical analysis (DMA) results showed a strong reinforcing effect of CNC that depends on their origin (balls or leaves). The difference was attributed not only to differences in the aspect ratio of CNC but also to the stiffness of the percolating network of nanoparticles.

Development and optimisation of a non conventional extraction process of natural dye from olive solid waste using response surface methodology (RSM)

Dyes obtained from different natural sources have emerged as an important alternative to synthetic dyes. In this study, optimisation of natural colorant non-conventional extraction technique from olive waste was investigated using response surface methodology. The combined effects of extraction conditions on total phenolic content (TPC) and relative color strength (K/S) were studied using a three-level three-factor Box-Behnken design. The optimum conditions for dye extraction were found to be 0.14mol/L, 62.11min, 71.23°C and 4.5g for sodium hydroxide concentration, extraction time, temperature, and mass of the waste, respectively. The efficiency of extraction under these optimum conditions was found to be 1133.86mg/L of phenolics and relative colour strength (K/S) equal to 23.22. Further, Fourier Transform Infrared Spectroscopy was used to identify the major chemical groups in the extracted dye.

Experimental evaluation of eco-friendly flocculants prepared from date palm rachis

Sodium carboxymethylcellulose (CMCNa) is an anionic water soluble polyelectrolyte widely used in many industrial sectors including food, textiles, papers, adhesives, paints, pharmaceuticals, cosmetics and mineral processing. CMCNa was produced by chemical modification of cellulose, and represents many advantages: natural, renewable, non-toxic and biodegradable. In this study, different kinds of CMCNa, prepared from an agricultural waste date palm rachis, were tested as eco-friendly flocculants for drinking water treatment and their performances as flocculants in turbidity removal enhancement were assessed. The prepared materials were characterized by the degree of substitution (DS) and polymerisation (DP). The study of the effect of some experimental parameters on the coagulation-flocculation performance, using the prepared materials combined with aluminium sulphate (as coagulant), showed that the best conditions for turbidity treatment were given for pH 8, coagulant dose 20 mg/L, flocculant concentration of 100 mg/L and stirring velocity (during the flocculation step) of 30 r/min. Under the optimum conditions, the turbidity removal using CMCNa, prepared from raw material, was about 95%. A comparison study between the flocculation performance of a commercial anionic flocculant (A100PWG: polyacrylamide) and that of the prepared CMCNa showed that the performance of the waste-based flocculant with a DS of 1.17 and a DP of 480 was 10% better than that achieved by the commercial one.

Effect of the oxidation treatment on the production of cellulose nanofiber suspensions from Posidonia oceanica: The rheological aspect

Different grades of cellulose nanofibrils (CNF) were prepared from Posidonia oceanica balls and leaves (POB and POL). Pretreatment using 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation was performed to facilitate the fibrillation during ultrafine friction grinding process. The ensuing CNF batches were compared in terms of morphology and degree of fibrillation. The rheological properties of the produced CNF suspensions were also analyzed for varying doses of sodium hypochlorite used during the TEMPO- mediated oxidation procedure. The stronger fibrous network structures were formed when increasing the oxidant concentration, which was confirmed by the increase of the storage moduli value. P. oceanica balls were found to undergo stronger fibrillation and, consequently, to form stronger networks, compared to P. oceanica leaves, when using equivalent concentration of the oxidizing agent.

Green dyeing process of modified cotton fibres using natural dyes extracted from Tamarix aphylla (L.) Karst. leaves.

Abstract This research work involves an eco-friendly dyeing process of modified cotton with the aqueous extract of Tamarix aphylla leaves. During this process, the dyeing step was carried out on modified cotton by several cationising agents in order to improve its dyeability. The influence of the main dyeing conditions (dye bath pH, dyeing time, dyeing temperature, salt addition) on the performances of this dyeing process were studied. The dyeing performances of this process were appreciated by measuring the colour yield (K/S) and the fastness properties of the dyed samples. The effect of mordant type with different mordanting methods on dyeing quality was also studied. The results showed that mordanting gave deeper shades and enhanced fastness properties. In addition, environmental indicators (BOD5, COD and COD/BOD5) were used to describe potential improvements in the biodegradability of the dyebath wastewater. Further, HPLC was used to identify the major phenolic compounds in the extracted dye.

Sustainability issues of ultrasonic wool dyeing with grape pomace colourant

Abstract In this study, the ultrasound technique was investigated to dye wool fabrics with the natural extract obtained from grape pomace as a way of reducing time, temperature and environmental impact. Indeed, this natural material was very rich in total polyphenolic compounds and total flavonoids (which are, respectively, 310 (mg GAE/L) and 75 mg (CE/L)). Further, Fourier Transform Infrared Spectroscopy showed that the major chemical groups identified in the extracted dye and in the dyed wool fabrics are characteristics of phenolic compounds. The experimental findings of the dyeing process showed that ultrasound method could improve obviously the dye exhaustion and fixation which resulted in improving considerably the colour yield (K/S) and the fastness properties of dyed fabrics compared to the conventional heating method.

Development and Optimization of the Extraction Process of Natural Dye from Tamarix aphylla (L.) Karst. Leaves Using Response Surface Methodology (RSM)

The extraction of colorant from Tamarix aphylla (L.) Karst. leaves was optimized using response surface methodology (RSM). The combined effects of extraction conditions (sodium hydroxide concentration, sample weight, and extraction time and temperature) on the total phenolic content (TPC) and color yield (K/S) were studied using three-levels three-factors Box-Behnken design. The optimum conditions for dye extraction were found to be 0.25 mol/l, 65 min, 88 °C and 52.5 g/l for sodium hydroxide concentration, extraction time and temperature, and mass of the leaves powder respectively. The efficiency of extraction under these optimum conditions was found to be 1.12 g/l of phenolics and color yield equal to 11.20. Further, high-performance liquid chromatography analysis (HPLC) was used to identify the major phenolic compounds in the dye extract such as gallic acid, quercetin, luteolin, and kaempferon.

A novel natural source Vicia faba L. membranes as colourant: development and optimisation of the extraction process using response surface methodology (RSM)

Abstract In this research paper, an eco-friendly extraction process of dyes from Vicia faba L. membranes was developed. In this regard, the influence of independent process factors like the weight of material, the extraction time, the temperature and the sodium hydroxide concentration on the natural dye extraction from Vicia faba membranes was investigated. The optimisation of the extraction conditions and the effect evaluation of the different operating parameters were carried out using a Box–Behnken design under response surface methodology. The optimum conditions were found to be 66 °C, 90 min, 5 g and 0.1628 mol·L−1 for extraction temperature, time, mass of the material and sodium hydroxide concentration, respectively. The efficiency of this extraction process under these optimum conditions was evaluated by measuring the total phenolic content (TPC), the total flavonoid content and the relative colour yield (K/S). In these operating conditions, good fastness ratios were observed for the dyed fabrics.

Comparative study on the chemical constituents of essential oils from different organs of the Sicilian Kundmannia (Kundmannia sicula L.) DC. (Apiaceae) growing spontaneously in Tunisia

Essential oils from odorous and volatile compounds possessing several therapeutic benefits are considered of a paramount importance in everyday human life. This study deals with a comparative study of essential oils from different parts of an aromatic plant Kundmannia sicula (L.) DC. (Apiaceae) growing in Tunisia. The hydro-distilled essential oils of the leaves and inflorescences with mature seeds (IMS) of K. sicula were analysed for the first time by gas chromatography equipped with flame ionisation detector and gas chromatography coupled with mass spectrometry. Fifty leaves and 47 IMS constituents were identified, accounting for 97.9% and 98.2% of the total oil, respectively. The major compounds identified from the leaves and IMS oils were isocurcumenol (9.9–10.1%), hexadecanoic acid (9.5–10.9%), spathulenol (6.9–3.4%), 10-epi-γ-eudesmol (6.3–5.5%), α-cubebene (5.9–6.1%) and trans-dihydro occidentalol (52–6.6%). The essential oil consists mainly of oxygenated monoterpenes (50.7–53.2%).

Synthesis and characterization of cellulose carbonate using greenchemistry: Surface modification of Avicel

The development of new derivatives based on renewable natural resources using green chemistry is a concept gaining recognition in several industries. This work focused on the preparation and characterization of cellulose carbonate using dimethyl carbonate as the green reagent in ethanoic KOH solution. The effect of several reaction parameters were evaluated, i.e., temperature (25°C, 50°C, 90°C, 120°C, 150°C, and 180°C), time (6, 24, 48, and 72h), KOH concentration (15% and 30%), and the use of a catalyst (DBU). The degree of substitution (DS) of the resulting materials was evaluated by 13C CP/MAS NMR. The spectra of the prepared cellulose carbonate exhibited the main peaks associated with cellulose macromolecules (C1-C6) and those corresponding to carbonate functions at approximately 162ppm. Moreover, XPS was performed and confirmed the reaction modifications. Nevertheless, it is worth noting that 13C NMR and XPS spectra showed a significant difference in DS value, due to the difference between both techniques. However, our results from NMR and XPS experiments confirm that the major modifications during all the reactions occurred mainly at the surface. This green process opens the way for the easy production of a new class of cellulose derivatives.