Advances in Sustainable Valorization of Natural Waste and Biomass

The purpose of this study is to propose a fully sustainable dyeing process for nylon 6. In order to achieve this goal, Rhubarb flower parts were used to produce a brown hue on nylon 6 fabric. The effects of dyeing parameters such as dyeing time, temperature, dyebath pH, M:L, salt addition, dispersing agent, and dye concentration on color strength were investigated. Using 100%owf dye in an acidic medium at boil and the material to liquor ratio of 1:30 for 75 min was determined to be the optimal condition for dyeing nylon 6 with rhubarb flower. In order to achieve acceptable color fastness, four natural mordants were applied, including walnut husks, pistachio hulls, pine cones, and green coffee. Colorimetric measurements revealed that mordanting did not affect the hue of the color compared to the non-mordant sample. In addition, diverse natural mordants produced the same color (i.e., brown) with varying color strengths, of which 10%owf walnut husk generated the strongest color. Bio-mordanted samples were also found to have excellent color fastness, thereby providing an effective substitute for metal mordants. Full article

This investigation was focused on evaluating the utilization of Leather-waste, i.e., “Leather Shavings”, to develop “Poly(ethylene-vinyl-acetate)” (EVA) based “polymer matrix composites”. Composites with the highest ratio of 1:1 were developed using a rolling-mill, which was then subjected to hot-press molding for value-added applications, notably in the “floor-covering”, “structural”, “footwear”, and “transportation domain”. The specimens were examined for evaluating the “physico-mechanical characteristics” such as, “Compressive and Tensile, strength, Abrasion-resistance, Density, tear-resistance, hardness, adhesion-strength, compression, and resilience, damping, and water absorption” as per standard advanced testing techniques. Raising the leather-fiber fraction in the composites culminated in considerable enhancement in “physico-mechanical characteristics” including “modulus”, and a decline in “tensile-strain” at “fracture-breakage”. The thermo-analytic methods, viz. TGA and DSC studies have evidenced that substantial enhancement of thermo-stability (up to 211.1–213.81 °C) has been observed in the newly developed PMCs. Additionally, the DSC study showed that solid leather fibers lose water at an endothermic transition temperature of around 100 °C, are thermo-stable at around 211 degrees centigrade, and begin to degrade at 332.56-degree centigrade for neat recycled EVA samples and begin to degrade collagen at 318.47-degree centigrade for “leather shavings/recycled EVA polymer composite samples”, respectively. Additionally, the “glass transition temperature” (T_g) of the manufactured composites was determined to be between −16 and 30 °C. Furthermore, SEM and EDAX analysis have been used to investigate the morphological characteristics of the developed composites. Micrograph outcomes have confirmed the excellent “uniformity, compatibility, stability and better-bonding” of leather-fibers within the base matrix. Additionally, the “Attenuated-total-reflection” (ATR-FTIR) was carried out to test the “physicochemical chemical-bonding”, “molecular-structure”, and “functional-groups” of the “base matrix”, and its “composites” further affirm the “recycled EVA matrix” contained additives remain within the polymeric-matrix. An “X-ray diffraction study” was also conducted to identify the “chemical-constituents” or “phases” involved throughout the “crystal-structures” of the base matrix and PMCs. Additionally, AFM analysis has also been utilized to explore the “interfacial adhesion properties” of mechanically tested specimens of fabricated polymeric composite surfaces, their “surface topography mapping”, and “phase-imaging analysis” of polymer composites that have leather-shavings fibers. Full article

The textile industry is one of the most complex sectors, in terms of the materials and chemical processes used from petroleum and the environmental degradation during its production and disposal. It is therefore a sector looking for new possibilities and for more sustainable materials and applications. One option is to use natural dyes, as they are considered biodegradable, do not pollute the environment, and have potential use for many sectors, including the fashion industry. In this study, Alanya silk was dyed by a natural dyeing method with crocus sativus, Helichrysum arenarium, and Glycyrrhiza glabra L., plants that grow in and around the Alanya region. Quercus aegilops L. grown in the region was preferred as mordant, a natural binder, and is one of the plants with the highest tannin content, and it was used with a more environmentally friendly and sustainable approach to increase the binding in natural dyeing instead of chemical mordants. The aim is to provide an environmental and scientific contribution to the dyeing producers in this region. According to the MAUT (Multi-Attribute Utility Theory) method, the best dyes in terms of fastness and color efficiency were determined as the dyes made with the Glycyrrhiza glabra L. plant. Full article

The present research work was conducted on developing sustainable production of mulberry filament silk fabric dyed with different extracted dye solutions based on extraction ratios of 1:4, 1:6, 1:8, and 1:10 from neem (Azadirachta indica) leaves. The research work focused on evaluating the antimicrobial and mosquito repellent properties of dyed silk fabric. In the experiment, the samples were dyed using the exhaust method at different dye bath concentrations i.e., 15 g/L, 20 g/L, and 25 g/L in the presence and absence of mordant at 80 °C maintaining 1:60 dyeing liquor ratio. The absorbance of the extracted dye solutions was determined with a UV/VIS spectrophotometer, which detected the highest absorbance of 7.73 at the peak 490 nm of λmax of 1:4 extracted dye solution. Fourier transform infrared (FTIR) spectroscopy was used to investigate the chemical structure of dyed fabrics; however, no chemical changes or bond formation occurred; instead, dye particles were deposited on the fabric layer, indicating the presence of bioactive components. Allergy test was also performed to confirm allergic reactions of neem extract on human skin. The antimicrobial activity of extracted dye solutions and dyed samples was estimated against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria using the agar diffusion method and mosquito repellency of fabrics were examined by the cage method. The results emphasized that dyed fabric with the highest concentrated dye solution, 1:4 extraction, and highest dye bath concentration, 25 g/L along with mango bark mordant solution, possesses the highest antimicrobial activity in terms of an inhibition zone of 0.67 mm against Gram-negative bacteria and 0.53 mm against Gram-positive bacteria obtained after incubation, and the highest mosquito repellent of 75% due to the absorption of active bio constituents. The experimental results also determined that the dyed fabric with 1:4 extracted dye solution exhibited good antimicrobial (inhibition zone, 0.65 mm against E. coli and 0.52 mm against S. aureus) and mosquito repellent property (66.67%). The experimental study also revealed that Potassium dichromate mordant reduced the antimicrobial (inhibition zone, 0.05 mm against E. coli and no inhibition against S. aureus) and mosquito repellent action (33.33%). In conclusion, the data revealed that the increase in the extraction ratio of dye solution and dye bath concentration has no impact on the silk fibroin; it only impacts what is deposited on the fabric layer that improves its antimicrobial and mosquito repellency. The current research showed that neem leaves were found to have a beneficial effect in controlling microorganisms and mosquitoes through a sustainable approach. Full article

Natural wastes are widely used as composts for plant growth. However, wool waste has received little attention in this regard, despite its nitrogen-rich chemical structure owing to amide groups. A few studies have been conducted for soil amendment using wool, mostly in raw or pellet form. However, despite the possible consistent mixing and more uniform effect of powders inside soil, wool has never been implemented in powder form in soil for improving moisture. This study demonstrates the effectiveness of using wool as a powder, facilitating better mixing and spreading in soil. Results show that wool powders are more effective in retaining soil moisture compared to wool pellets and are comparable to commercial fertiliser. The findings further indicate that a balanced amount of wool is required to maintain a proper moisture level (not too wet or dry) to promote actual plant growth. Full article

The recent pandemic scenario has caused demand for green products that have medicinal aspects, as well as greener approaches for global health. Natural dye from plants, particularly from harmal seeds, is an excellent alternative to carcinogenic yellow synthetic dyes. The current study has been conducted to isolate natural colorants from harmal seeds in methanolic medium through Gamma-Assisted Extraction (GAE). The dyeing variables that are necessary for shade development before and after mordanting were selected. It has been found that 6 kGy is the optimal absorbed dose for extraction of colorant from 6 g of powder to isolate the colorant in the methanolic medium through the Gamma-irradiated extraction mode (GAE). To get excellent results, 30 mL of methanolic extract containing 6 g/100 mL of Glauber salt was sued for dyeing of irradiated wool at 45 °C for 65 min. For improving the color strength and acceptable rating of fastness, 9% of henna, 3% of acacia, 10% of turmeric, and 7% of pomegranate extracts as pre-bio-mordants as well as 7% of acacia, 3% of pomegranate, 9% of henna, and 10% of turmeric extracts as post-mordants have given high results compared to when chemical mordants have been used. It was concluded that Gamma-ray treatment has excellent color strength in the dyeing of bio-mordanted wool using harmal seed extracts under mild conditions, and has good fastness ratings after using chemical and bio-mordanting methods as well. Full article

Great advances have been made in the preparation of bioplastics and crude oil replacements to create a better and more sustainable and eco-friendly future for all. Here, we used cassava bagasse fibers at different ratios as reinforcement material to enhance the properties of black seed w-cornstarch films using the facile solution casting technique. The reinforced films showed compact and relatively smoother structures without porosity. The crystallinity values increased from 34.6 ± 1.6% of the control to 38.8 ± 2.1% in sample CS-BS/CB 9%, which reflects the mechanical properties of the composite. A gradual increase in tensile strength and elastic modulus was observed, with an increase in loading amounts of 14.07 to 18.22 MPa and 83.65 to 118.32 MPa for the tensile strength and elastic modulus, respectively. The composite film also exhibited faster biodegradation in the soil burial test, in addition to lower water absorption capacity. Using bio-based reinforcement material could significantly enhance the properties of bio-based packaging materials. The prepared hybrid composite could have a promising potential in food packaging applications as a safe alternative for conventional packaging. Full article

Green or sustainable cosmetics are products that contain natural ingredients obtained from renewable raw materials. Fruit peels represent a sustainable source of bioactive compounds. Polyphenols, e.g., flavonoids, have the ability to scavenge free radicals; thus they exhibit antioxidant activity. Recently, natural antioxidants have been in the limelight as being safe, effective, and versatile. In this study, antioxidant effects and the sun protection ability of apple (Malus domestica), banana (Musa sapientum), and orange (Citrus reticulata) peel extracts were evaluated in skincare formulations. The extraction of phenolic compounds was performed in three different solvents, i.e., ethanol, methanol, and acetone. Total phenolic contents, antioxidant activity, and sun protection factor were determined for the fruit peel extracts. The acetone extract of apple and ethanol extract of banana peels contained polyphenols, i.e., 24.3 ± 1.5 and 26.7 ± 0.6 mg GAE per gram of the extracts, respectively. These extracts showed DPPH radical scavenging activity and were incorporated into oil-in-water (O/W) cosmetic emulsions. All the formulated samples were found to be stable when subjected to centrifuging and thermal stress. Antioxidant activities of cream samples were above 80%, and the sun protection factor was above 15. The results have confirmed the applications of fruit peel waste in the formulation of photostable, antioxidant, and sun screen formulations. These creams would help to maintain skin health, protect it from UV radiation, and reduce the aging effect. Thus, fruit peel waste could present an ecofriendly and sustainable source of natural antioxidants for the personal care industry. Full article

The health risks associated with formaldehyde have propelled relevant stakeholders to push for the production of non-toxic wood adhesives. Several countries including the USA, Japan, and Germany have implemented policies mandating manufacturers to reduce the emissions of formaldehyde to lower levels. Protein adhesives stand out due to their sustainability, renewable sources, and biodegradability. However, they are limited by poor wet strength and water resistance, which affect their wide acceptability in the marketplace. Researchers have developed multiple strategies to mitigate these issues to advance protein adhesives so they may compete more favorably with their petroleum-based counterparts. This review paper explores these strategies including cross-linking, modified fillers, and the removal of hydrophilic content while providing insights into the methodological approaches utilized in recent literature with a comparison of the resultant protein adhesives. Full article

Bioenergy has emerged to be among the primary choices for the short- and medium-term replacement of fossil fuels and the reduction in greenhouse gas (GHG) emissions. The most practical method for transforming biomass into biofuel is thermochemical conversion, which may be broken down into combustion, torrefaction, pyrolysis, hydrothermal liquefaction, and gasification. In this study, producing biofuels using a biomass pyrolysis process was investigated. This study explored the pyrolysis process and operating conditions to optimize the process parameters to maximize the desired product yields and quality. The pyrolysis process produces three main products, which are bio-oil, bio-char, and gas. There are three classifications for the pyrolysis method, with each of them producing a majority of a certain product. First, slow pyrolysis is conducted in the temperature range of 300–950 °C and residence time of 330–550 s. It produces around a 30% oil yield and 35% char yield, and thus, the majority yield of slow pyrolysis is char. Second, fast pyrolysis produces around 50% oil, 20% char, and 30% gas yields with a temperature range of 850–1250 °C and a residence time of 0.5–10 s. The average yield of flash pyrolysis was found to be 75% bio-oil, 12% bio-char, and 15% gas, which is conducted within less than 1 s. It was reported that the pyrolysis of biomass was simulated using ASPEN Plus, where the effects of several parameters, such as the temperature, heating rate, and residence time, on the product yield and composition were investigated. Pyrolysis was performed under different conditions ranging from 400 to 600 °C. The effects of different catalysts on the pyrolysis process were studied. It was found that the addition of a catalyst could increase the yield of bio-oil and improve the quality of the product. The optimal operating condition for the pyrolysis process was determined to be a temperature of 500 °C, which resulted in a higher bio-oil yield. It was found that the biofuel yield was enhanced by selecting appropriate raw materials, such as rice husk, along with the pyrolysis temperature (e.g., 450 °C) and particle size (350–800 µm), and using a low residence time and pressure. Full article

The extensive use of dyes in numerous industries results in massive dye discharge in the wastewater, which is a major cause of water pollution. Globally, the consumption of dyes is near seven hundred thousand tons across different sectors, of which around 10–15% goes into the wastewater. Among the dye kinds, anionic dyes make up the main proportion, having a 32–90% share in the wastewater. Different plant-derived wastes, which are sustainable given their natural abundance, effectiveness, and low cost, are frequently proposed for dye separation. However, these adsorbents are inherently more suitable for cationic dyes than anionic dyes. In recent years, the modification of these wastes has been progressively considered to suit them to anionic dye removal. These modifications involve mechanical, thermal, or chemical treatments, or combinations. These attempts propose two-way benefits, as one abundant waste is being used to cure another severe problem, and eventually both could be diminished. This review has a key focus on the evaluation of plant-derived adsorbents and their modifications, and particularly for anionic dye adsorption. Overall, the mechanism of adsorption and the suitability of the current methods are discussed, and their future potential is explored. Full article

Worldwide demand for man-made cellulosic fibres (MMCF) are increasing as availability of cotton fibre declines due to climate change. Feedstock for MMCF include virgin wood, agricultural residues (e.g., straw), and pre- and post-consumer cellulosic materials high in alpha-cellulose content. Lyocell MMCF (L-MMCF) offer large advantages over other MMCF processes in terms of both environmental and social impacts: the solvent for cellulosic dissolution, n-methyl-morpholine-n-oxide, can be recycled, and the process utilizes non-toxic chemicals and low amounts of water. Hemp can be a preferential cellulosic feedstock for L-MMCF as hemp cultivation results in carbon dioxide sequestration, and it requires less water, fertilizers, pesticides, and herbicides than other L-MMCF feedstock crops. These factors contribute to hemp being an environmentally conscious crop. The increased legalization of industrial hemp cultivation, as well as recent lifts on cannabis restrictions worldwide, allows accessibility to local sources of cellulose for the L-MMCF process. In addition, hemp biomass can offer a much larger feedstock for L-MMCF production per annum than other cellulosic sources, such as eucalyptus trees and bamboo. This paper offers perspectives on the agricultural, manufacturing, and economic opportunities and challenges of utilizing hemp biomass for the manufacturing of L-MMCF. Full article