Magda Emil Tawfik

To enhance and widely spread the bioactive sustainable applications of chitosan (CH), three newly developed solid chitosan derivatives were prepared and characterized. Chitosan was obtained from shrimp shell wastes through alkaline deacetylation of its precursor chitin. The obtained CH was reacted with bis-(hydroxyethyl) terephthalate (BHET), which was derived from the recycling of post-consumer PET waste, to create the first derivative, referred to as CBHET. This derivative was then transformed into a second chitosan derivative by grafting with acrylic acid (AA) denoted as CBHET–AAI. The third chitosan derivative was produced by simultaneously reacting CH with both BHET and AA, added at the same time, and this product was designated as CBHET–AAII. The structural characteristics of the three prepared chitosan derivatives were evaluated and confirmed by applying Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermal analyses (TGA, DTG and DSC), and scanning electron microscopy (SEM). Factors that could affect the properties of the final products were investigated, including treatment temperature, reaction time, and reactant concentrations. The three derivatives were found to be very hard, solid composites, insoluble in most common solvents, acids, bases, and even water. Based on TGA data, CBHET exhibited the highest mass loss at 63.4%, compared to 57.7% for CBHET–AAI and 41% for CBHET–AAII. The crystallinity index (ICR), average crystalline size (D) in ηm, and average interchain spacing in A° were also calculated. According to the data obtained, it can be concluded that these chitosan derivatives are ideal bioactive, sustainable, and newly developed biopolymers based on two waste ingredient materials: namely chitosan from shrimp shell wastes and BHET from glycolysis of post-consumer PET. These novel derivatives can be utilized efficiently and safely as a sustainable biosorbent in the handling of wastewater management, treatment of low- and medium-level radioactive waste effluents, and many other potential applications.

This study investigates the long-term resistance of an environmentally friendly composite made from a blend of local Ordinary Portland Cement (OPC) and ground granite waste powder (G). The composite was subjected to complete static immersion for up to twenty-four weeks in three types of water: potable water, groundwater, and seawater. The experimental work evaluated the effects of exposure to these three water types on various characteristics of the granite–cement composite (GCC), including compressive strength, mass gain, portlandite [CH] content, bulk density (D), total porosity (p), compactness, water absorption (A), and pH of the immersing media. Additionally, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal analysis (TGA and DTA) were used to investigate how exposure to the three water environments altered the internal microstructure of the hydration phases of the composite over the twenty-four-week period. This systematic approach provides valuable insights into the variations that may occur in solid hydration outcomes and their sustainability in flooding scenarios. The data obtained from these analyses revealed that the granite–cement composite exhibits acceptable thermal resistance and endurance to deterioration in aquatic environments. The cement formulation contains 20% by mass of ground granite waste powder, with a water-to-cement ratio of 35%. After 24 weeks of complete static immersion, the composite achieved compressive strength values close to 24 MPa. Solidifying radioactive waste in cement–granite is a newly developed method that improves sustainability by formulating a more stable, durable, cost-effective, and less hazardous waste form. Therefore, the granite–ordinary cement composite being studied is recommended as an inert matrix for solidifying and stabilizing certain categories of radioactive waste.

A conventional chemical method was applied for the extraction of chitosan (CH) from shrimp shell wastes (SSWs) in three stages: (1) Demineralization: SSWs were treated with HCl to remove minerals. (2) Deproteinization: NaOH was used to eliminate proteins from the demineralization shells. 3: Deacetylation: The chitin (CT) obtained from stage 2 was converted to chitosan in alkaline medium using NaOH. This study aims to demonstrate the impact of varying deacetylation times on chitosan surface morphology, elemental composition, thermal resistance, structural configuration, and deacetylation degree (DD). Variable techniques including UV-visible spectroscopy, Fourier Transformed Infra-Red (FTIR-ATR), Thermogravimetry (TG/DTG), Scanning Electron Microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX) analyses were employed to analyze how increased deacetylation periods affect the characterization of the products. The FTIR spectra showed a notable similarity between all extracted chitosan processed with increasing deacetylation time and the commercial one. Moreover, the results revealed that all the extracted chitosan samples acquired DD values, based on FTIR-ATR analysis, are comparable to that of commercial ones i.e. 79.54%, 78.23%, 74.81%, and 76.56% for deacetylated times of 22 h, 30 h, 36 h, and 40 h, respectively are comparable to that of the commercial chitosan (76.1%). Furthermore, the EDX analysis confirms that the extracted chitosan is non-toxic product, making it suitable for various applications, including biological and medical uses. Graphical Abstract

A conventional chemical method was applied for the extraction of chitosan (CH) from shrimp shell wastes (SSWs) in three stages: 1. Demineralization: SSWs were treated with HCl to remove minerals. 2. Deproteinization: NaOH was used to eliminate proteins from the demineralization shells. 3: Deacetylation: The chitin (CT) obtained from stage 2 was converted to chitosan in alkaline medium using NaOH. This study aims to demonstrate the impact of varying deacetylation times on chitosan surface morphology, elemental composition, thermal resistance, structural configuration, and deacetylation degree (DD). Variable techniques including UV-visible spectroscopy, Fourier Transformed Infra-Red (FTIR-ATR), Thermogravimetry (TG/DTG), Scanning Electron Microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX) analyses were employed to analyze how increased deacetylation periods affect the characterization of the products. The FTIR spectra showed a notable similarity between all extracted chitosan processed with increasing deacetylation time and the commercial one. Moreover, the results revealed that all the extracted chitosan samples acquired DD values, based on FTIR-ATR analysis, are comparable to that of commercial ones i.e. 79.54%, 78.23%, 74.81%, and 76.56% for deacetylated times of 22 hrs, 30 hrs, 36 hrs, and 40 hours, respectively are comparable to that of the commercial chitosan (76.1%). Furthermore, the EDX analysis confirms that the extracted chitosan is non-toxic product, making it suitable for various applications, including biological and medical uses.

The freezing/thawing (F/T) reliability of radioactive final waste form (FWF) is experiencing progressive important structural task during the long term disposal period. In this study, a cement-granite composite matrix (GCC) based on granite (G) scrape wastes, at 20% to the mass of the cement (C) mixed at 35 mass% plain water relative to both C & G masses, was developed. The frost resistance of the developed composite was evaluated through freezing and thawing cycling. The F/T integrity of the GCC was assessed through the evaluation and determination of the mass losses, compressive strength and porosity values. The alterations in internal microstructures of granite-cement composite were examined by applying X-Ray diffraction (X-RD), thermal analysis (TA) and scanning electron microscopy (SEM). It was dedicated that ameliorations in the characters of the GCC, under consideration, due to freezing/ thawing treatments could be differentiated into three steps: slow-impairment step, fast-spoil step, and stable step. The obtained experimental results, after 180 days of F/T treatment, recommended a basis for the suitability of the developed granite–cement composite and candidate it for solidification/stabilization of some low and medium radioactive wastes. However, evaluation of frost stability in large-scale composite structures is mandatory.

The present study investigates to incorporate spiked sulfate solution simulate into polymer–cement composite (PCC) based on recycled expanded polystyrene foam. The main aim is to convert the waste stream into leach resistance solid forms able to slow down or even to retard the back release of hazardous radionuclides to the surrounding. Effective parameters e.g. leachant medium, temperature, radioactivity contents, leachant volumes and radionuclides speciation versus the leaching time were studied. The incremental leach rate (Rn, cm/day) and the leach index (Lx) were evaluated for the final waste form after 145 days. The experimental results revealed that the Lx for the all variances can fulfil the waste acceptance criteria for the disposal facility and are above the threshold value of 6. Moreover, leach rate percentages for Cs-134 and Co-60 were not exceeding 2%. The acquired data, based on lab leaching experiments, can recommend the developed PCC under consideration for solidification of radioactive sulphate waste stream safely.

In our previous investigations, a hard wood composite (HWC) was formulated by adding rice straw, as a filler to the recycled polystyrene foam waste at mass ratio (50/50) at 170 °C and pressed under 40 kPa. Here, the disposed HWC product as a model scrap was applied for production of porous carbons enclosed with graphene sheets. To attain this approach, HWC was hydrothermally carbonized (S1) followed by either post-heat treatment (S2) or potassium hydroxide (KOH, S3) activation at 750 °C for 2 hours. The properties of prepared samples were evaluated using SEM, ATR-IR, and porosity measurements. The adsorption performance of the obtained porous carbons toward removal of lead (Pb(II)) and cadmium (Cd(II)) ions from aqueous solutions was investigated under different operating conditions like contact time, initial pH, initial metal ions concentration and adsorbent dose. Kinetic models such as pseudo-first order, pseudo-second order and intraparticle diffusion were used to analyze the adsorption data. Langmuir, Freundlich, Dubinin–Radushkevich and Redlich–Peterson isotherms were applied. Thermodynamics and regeneration studies were performed. The sample (S3) comprised a micro-mesoporous carbon structure encompassed by graphene sheets, with the largest total surface area (422 m² g⁻¹) and adsorption capacities for Pb(II) and Cd(II) ions of 207.9 and 119.6 mg g⁻¹, respectively. The experimental adsorption data were best elucidated using Langmuir and pseudo second-order kinetic models. Thermodynamic experiments confirmed that adsorption is an endothermic and spontaneous process. Conclusively, the investigated HWC waste is a promising carbonaceous precursor for preparing effective porous graphene-carbons used in the removal heavy metals from their aqueous stream.

The core objective of the present study is to develop an added value cement–granite composite (CGC) based on granite (G) scraps and Ordinary Portland Cement (OPC). The granite scraps were collected, washed, ground, sieved, and the finest powder was used as an inorganic admixture for developing the CGC. Plain water was added to the granite–cement powder and thoroughly mixed. The obtained pastes were casted for 28 days prior to their physical, structural, thermal characterizations and their mechanical evaluation. Factors assumed, mostly, to affect the final properties of the CGC blocks, e.g. granite/cement and water: cement ratios were studied. The reached monolith cement–granite composite has many advantages, e.g. lower density, very low water absorption percentage, acceptable compressive strength values and significant radiation and thermal stability. Based on the experimental data reached it could be stated that: for its economical advantages, where the one of its basic components is a waste. In addition to the acceptable mechanical traits of the developed composite, it can be candidate properly as an inert matrix for some radioactive wastes containment, for application in many field including: construction sector (interior and exterior of household walls, floor tiles, etc.), and for many others. The environmental reward due to management the accumulated problematic solid granite scraps is, certainly, a gain.

The objective of the present study is to formulate added value polymer granite composite (PGC) based on granite (G) waste scraps as filler and unsaturated polyester (UP) obtained from chemically recycled post-consumed poly (ethyleneterephthalate) wastes (PET) as a matrix to be used in different candidate applications. Both wastes were collected from local dumping sites. Factors affecting the properties of the acquired PGC products e.g. polymer constitutions, granite/styrenated polyester ratios were studied systematically. The reached polymer granite composite has many advantages e.g. low density, very small water absorption percentage, short curing and hardening time, acceptable compressive strength values and significant thermal stability. Moreover, the environmental reward due to the utilisation of accumulation of the two problematic solid wastes is certainly a gain.

Purpose: Automotive coating materials are very important items for this industry. However, their performance is limited by the use of excessive amounts of solvents in their formulations, whereas the emission of volatile organic solvents is against the widely ascending principle of green chemistry. Thus, this study aims to overcome this global problem to save the environment without affecting the properties and performance of the coating.Design/methodology/approach: High solid content paint formulation for automotive applications has been designed with low amount of volatile organic solvents with the aid of a functionalized hyperbranched modifier.Findings: It was found that the presence of a hyperbranched additive allows a high solid content to be designed and facilitate the processing, which indicates its liability to compensate the role played by excessive solvents amounts. In addition, the mechanical properties and physical characteristics of the modified coatings showed outstanding performance and preservation of clarity in comparison with the commercial counterparts.Practical implications: A high solid content coating with facile processing and improved performance leads to cheaper price beside the positive impact on the environment considering the limited emission of volatile organic contents.Social implications: Limitation of the used volatile organic compounds in any industry helps to save the health of humans and keep the environment unaffected.Originality/value: The use of functionalized hyperbranched additive to automotive coatings is a very promising additive for automotive coatings with optimized characteristics.