Approach For Valorization Research Articles

Lignin‐derived carbon materials for catalysis and electrochemical energy storage

AbstractLignin is abundant in green biomass. However, most of the lignin remains to be utilized. Lignin‐derived carbons (LDCs) provide a feasible approach for lignin valorization. Owing to the coupling merits of low cost, tunable morphologies, and high porosity, LDC materials have drawn extensive attention in the fields of catalysis and electrochemical energy storage. This review summarizes the recent advances in LDC materials and their applications in catalysis, supercapacitors, and secondary batteries. The bottlenecks and future trends are proposed for the further development of advanced LDCs. This review is expected to guide the preparation of high‐value‐added LDCs.

Insights into the characteristics and mechanism of vacuum drying technology for municipal sludge processing

Vacuum drying is an effective approach for sludge treatment and valorization. However, the vacuum drying of sludge has not been industrialized at present. The objective of this study was to elucidate the vacuum drying characteristics of static sludge and crack initiation mechanism. Our results indicate that crusting on the sludge surface under a high vacuum inhibited drying by reducing major cracks at sludge thicknesses of 13.6 and 10.2 mm. The inhibition effect weakened with decreasing sludge thickness. At 6.8 mm, the mean drying rate (VM) was the lowest at 0.08 MPa, while VM decreased with increasing vacuum degree at thicknesses of 13.6 and 10.2 mm. The decrease in drying rate could be attributed to rapid evaporation on the sludge surface under a high vacuum, leading to crusting, which inhibited crack initiation. VM was raised by 67.9–162.2% from 10.2 to 6.8 mm because the suction force of vacuum on water was much higher than the resistance to water diffusion of small isolation piles at 6.8 mm. Additionally, this study provided essential information to improve existing sludge treatment methods.

A sustainable approach for fish waste valorization through polyhydroxyalkanoate production by Bacillus megaterium NCDC0679 and its optimization studies

A sustainable approach for fish waste valorization through polyhydroxyalkanoate production by Bacillus megaterium NCDC0679 and its optimization studies

Effect of operating parameters on rice mill wastewater treatment in an acidogenic chamber and MFC coupled system

Acidogenic bioconversion of rice mill wastewater (RMW) into volatile fatty acid (VFA) represents an interesting approach for wastewater valorization. In this study, an acidogenic chamber was coupled with a dual-chambered MFC having a ceramic membrane (AC-MFC). A short hydraulic retention time (HRT) was employed for the two-step anaerobic treatment (acidogenesis and electrogenesis) to prevent the proliferation of methanogens. The effect of pH (5.5–7.5) and HRT (0.5 d–0.75 d) were investigated to understand the influence of operating parameters on the performance of the integrated system. The maximum VFA concentration of 1065.15 ± 5.08 mg COD/L was achieved at pH of 7.5 and HRT of 0.5 d. Under these operating conditions, the activity of acid-forming microorganisms and exoelectrogens improved remarkably, and the power density obtained from the system reached 4.72 ± 0.10 W/m3. The current study reveals an excellent potential for simultaneous RMW treatment and power generation in AC-MFC systems.

From Lignin to Chemicals: An Expedition from Classical to Modern Catalytic Valorization Technologies

AbstractFor the transition towards greener biorefineries with reduced waste, valorization of lignin to drop‐in chemicals instead of their combustion for energy purposes is a key issue for future processes. In this context, lignin should be extracted from lignocellulosic biomass (LCB) and fragmented into smaller units, followed by catalytic funneling to fine chemicals. In this review, we report on the classical approaches for lignin valorization from LCB: thermal treatments, solvolytic valorization, acid‐catalyzed process, and base‐catalyzed process. We also provide the reader with the modern approach of lignin valorization that led to an integrated LCB biorefinery. The performance of different solid catalysts in lignin‐first approach via reductive or oxidative catalytic fractionation at different conditions is discussed in detail.

Environment impact and bioenergy analysis on the microwave pyrolysis of WAS from food industry: Comparison of CO2 and N2 atmosphere.

The alarming output of waste activated sludge (WAS) from industries requires proper management routes to minimize its impact on the environment during disposal. Pyrolysis is a feasible way of processing and valorizing WAS into higher-value products of alternate use. Despite extensive research into the potential of WAS through pyrolysis, the technology's long-term viability and environmental impact have yet to be fully revealed. In addition, the environmental effects of utilizing different pyrolysis atmosphere (N2 or CO2) has not been studied before, although benefits of CO2 reactivity during pyrolysis have been discovered. This study evaluates the process's environmental impact, carbon footprint, and bioenergy yield when different pyrolysis atmospheres are used. The global warming potential (GWP) for a functional unit of 1t of dried WAS is 203.81kg CO2 eq. The heat required during pyrolysis contributes the most (63.7%) towards GWP due to high energy usage, followed by the drying process (23.6%). Transportation contributes the most towards toxicity impact (59.3%) through dust, NOx, NH3 and SO2 emissions. The initial moisture content of raw WAS (65%) greatly impacts overall energy consumption and environmental impact. Pyrolysis in an N2 atmosphere will result in a higher overall bioenergy yield (833kWh/tonne) and a lower carbon footprint (-1.09kg CO2/tonne). However, when CO2 was used, the specific energy value within the biochar is higher (22.26MJ/kg) due to enhanced carbonization. The carbon content of gas derived increased due to higher CO yield. From an energy perspective, the current setup will achieve a net positive bioenergy yield of 561kW (CO2) and 833kW (N2), where end products like biochar, bio-oil and gas can be used for power production. Despite the energy-intensive process, microwave pyrolysis has excellent potential to achieve a negative carbon footprint. The biochar used for soil amendment served as a good carbon sink. The utilization of CO2 as carrier gases provides a pathway to utilize anthropogenic CO2, which helps reduce global warming. This work demonstrates microwave pyrolysis as a negative emission, bioenergy-producing approach for WAS disposal and valorization.

Carbon Quantum Dot-Titanium Doped Strontium Ferrite Nanocomposite: Visible Light Active Photocatalyst to Degrade Nitroaromatics

The synthesis of carbon quantum dots (CQDs) from agricultural waste is a promising approach for waste valorization. In the present work, CQDs were synthesized using sugarcane bagasse as a carbon precursor. The nanocomposite of CQDs with trimetallic strontium–titanium ferrite was synthesized with an ultrasonication approach. The structural, magnetic and optical features of the synthesized nanocomposite and pristine NPs were studied using different analytical techniques. The TEM micrograph of the nanocomposite reveals the distribution of CQDs (8–10 nm) along with the agglomerated ferrite NPs. To validate the results, the photocatalytic efficiency of the nanocomposite, NPs and CQDs was comparatively studied for the photodegradation of nitroaromatic pollutants viz. p-nitrophenol, martius yellow and pendimethalin under visible-light irradiation. A nanocomposite having a 2:1 w:w ratio of CQDs and Sr0.4Ti0.6Fe2O4.6 displays an excellent photocatalytic performance, with the degradation efficiency ranging from 91.2 to 97.4%, as compared with 65.0–88.3% for pristine NPs and CQDs. These results were supported by band gap and photoluminescence analyses. The promising photocatalytic potential of the nanocomposite over the pristine CQDs and ferrite NPs could be ascribed to the increased specific-surface area (101.3 m2/g), lowering in band gap coupled with fluorescence-quenching which facilitated the transfer of photoinduced charge carriers. The impact of parameters affecting the photocatalytic process viz. pH, catalyst dose and contact time was also investigated. On the basis of quenching and gas chromatography-mass spectrometry (GC-MS) studies, plausible degradation pathways were proposed. The results highlight the broad potential of designing substituted ferrite-CQDs-based nanocomposites as reusable and visible-light-driven photocatalysts.

Valorization of microalgal biomass to value-added products using integrated supercritical CO2 extraction and sub-critical hydrothermal liquefaction

The study depicts the use of different extraction techniques to utilize each fraction of microalgal consortium biomass (Chlorella sp. and Phormidium sp.) for its conversion to value-added products (VAPs). The algal biomass was rich in proteins (30.8%), lipids (28.1%), carbohydrates and essential amino acids (36.29% of total protein). The lipid yield obtained after supercritical CO2 extraction (SFE) was found to be 3.0 ± 0.4% compared to the conventional soxhlet extraction (28.2 ± 2.3%) with chloroform: methanol (1:1 v/v). However, SFE extracted lipid showed higher Polyunsaturated fatty acids (PUFAs) content (20.68%) with the presence of eicosapentaenoic acid, docosahexaenoic acid, α-linolenic acid, linoleic acid and arachidonic acid. The PUFA content in lipid obtained after soxhlet extraction was only 3.48%. The residual biomass after SFE showed recovery of 17.1 ± 0.7% proteins and 27.1 ± 0.9 mg g−1 of total carotenoids. Subcritical-hydrothermal liquefaction (HTL) of the microalgae at 230 °C and 2.7 MPa produced 30.7% biocrude (dried biomass basis) containing aldehyde/ketone (37.14%), aromatics (27.63%) and alkanes/alkenes/alkynes (15.3%) along with other compounds. This fraction consisted of VAPs targeting multiple industries-food (11%), fuel (22%), pharmaceutical (56%) and cosmeceutical (12%). A novel approach including sequential SFE-HTL process showed a lower biocrude yield (8.6%) but showed upgradation in biocrude quality having 50% aromatic compound of which >48% were pyrazines derivatives (flavoring agents for the food industry) and 20.8% pharmaceutically valuable compounds, besides extracting PUFAs from SFE. Hence, a new microalgal valorization approach has been developed by integrating two extraction techniques to produce multiple VAPs to target a minimum waste generation approach.

A neoteric approach for the complete valorization of Typha angustifolia leaf biomass: A drive towards environmental sustainability.

Exploring new biomass resources and developing a sustainable process for holistic utilization has become crucial due to the high demand for bio-based chemicals as alternatives to petrochemicals. Herein, we describe a novel approach to valorize the Typha angustifolia leaves, underutilized biomass into cellulose, hemicellulose and lignin nanoparticles. The process was framed in a sequence to isolate hemicellulose in the first step due to its highly reactive nature and then separate cellulose and lignin. Among the various natural deep eutectic solvents used in screening experiments, LA/ChCl (2:1) was chosen for hemicellulose solubilization and a dissolution yield of 95.97±1.8% was obtained in 30min at 240W microwave power. Then the residual solid was delignified using NaOCl2 at 180W microwave power and a yield of 97±0.75% was obtained in 15min. Dissolved hemicellulose and lignin were precipitated using anti-solvents. The proposed approach achieved a recovery yield of 95.5±1.2% cellulose, 91.9±2.6% hemicellulose and 89.5±1.6% lignin. Subsequently, the isolated particles were converted into nanoparticles by intense ultrasonication. Spherical shaped nanocellulose, nanohemicellulose and nanolignin were obtained with an average size of 76±7nm, 86±9nm, and 64±5nm, respectively. The produced nanocellulose had a crystallinity of 77.36% with the thermal stability of 265°C. Nanohemicellulose and nanolignin were found to be semicrystalline with thermal stability up to 245°C and 275°C, respectively. The characterization results of the nanoparticles isolated from Typha angustifolia leaves are indicative of their wide range of biomedical and material science applications. This research could open a window for complete utilization of biomass in biorefinery and sustainable management of an invasive plant Typha angustifolia.

Construction of electron transport channels and oxygen adsorption sites to modulate reactive oxygen species for photocatalytic selective oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

Photocatalytic oxidation is an attractive approach for biomass valorization, but uncontrollable reactive oxygen species (ROS) inevitably initiates over-oxidation of target product, leading to low selectivity. Here we report that combining MnO2, WO3 with carbon nitride (CN) enables the construction of photocatalyst with electron transport channels and oxygen adsorption sites. Owing to the rapid transfer of photo-generated electrons to adsorbed O2, CN-WO3@MnO2 exhibited 13.5 and 1.18 times higher 1O2 and ∙O2- generation capacity than CN-WO3 with 92.8% lower ∙OH generation capacity, respectively. With the synergistic effect of ∙O2- and 1O2, 2,5-diformylfuran (DFF) selectivity up to 79.6% at high 5-hydroxymethylfurfural (HMF) conversion (77.6%) was attained. Both experimental results and density functional theory calculations indicate that the construction of electron transport channels and oxygen adsorption sites can deliberately modulate the generation of ROS with desired oxidation ability, thus facilitating the efficient and selective oxidation of HMF into DFF.

Combining Different Approaches for Grape Pomace Valorization: Polyphenols Extraction and Composting of the Exhausted Biomass

Grape pomace represents 60%, by weight, of the solid side-streams of the wine-making process. The quantities produced, seasonality, and the presence of polyphenols pose economic and environmental issues that require proper management approaches based on the principles of sustainability and circular economy. The present work focuses on the combined application of solid–liquid extraction of polyphenols from ground grape pomace using a hydroethanolic mixture and the composting of the exhausted pomace. The obtained results support the possibility of recovering approximately 76.5 g of extract per kg of dry grape pomace (or 1.8 g of total phenols per kg of dry grape pomace). The composting process was not affected by the extraction process. On the contrary, the composting process was enhanced by the pomace particle size reduction, in terms of final biostability and content of humic acids.

Unveiling the bioelectrocatalyzing behaviors and microbial ecological mechanisms behind caproate production without exogenous electron donor

Bioelectrochemical systems were proposed as a promising approach for the efficient valorization of biomass into 6–8 carbon atom medium-chain fatty acids (MCFAs), the precursors for high value-added chemicals or renewable energy, via acetyl-CoA-mediated chain elongation (CE). To achieve CE processes, exogenous electron donors (EDs), e.g., ethanol or lactic acid, were normally prerequisites. This research built a microbial electrolysis cell (MEC) for MCFAs biosynthesis from acetate without exogenous EDs addition. A wide range of applied voltages (0.6–1.2 V) was first employed to investigate the bioelectrocatalyzing response. The results show that caproate and butyrate were the main products formed from acetate under different applied voltages. Maximum caproate concentration (501 ± 12 mg COD/L) was reached at 0.8 V on day 3. Under this applied voltage, hydrogen partial pressure stabilized at about 0.1 bar, beneficial for MCFA production. Electron and carbon balances revealed that the electron-accepting capacity achieved 32% at 0.8 V, showing the highest interspecies electron transfer efficiency. Most of the carbon was recovered in the form of caproate (carbon loss was 9%). MiSeq sequencing revealed Rhodobacter and Clostridium_sensu_stricto playing the crucial role in the biosynthesis of caproate, while Acetobacterium, Acetoanaerobium, and Acetobacter represented the main ED contributors. Four available flora, i.e., homo-acetogen, anaerobic fermentation bacteria, electrode active bacteria, and nitrate-reducing bacteria, interacted and promoted caproate synthesis by molecular ecological network analysis.

Approaches for Management and Valorization of Non-Homogeneous, Non-Recyclable Plastic Waste.

The environmental accumulation of plastic wastes has become one of the most discussed topics in the scientific community. The development of new strategies to tackle this issue is of crucial importance, and different approaches are being investigated to effectively reduce plastic waste generated by improper or inefficient disposal. In addition to the efforts addressing the development of biodegradable plastics, the research is currently focused on the development of innovative recycling approaches. Indeed, although most plastic materials are potentially recyclable, only 15% of the worldwide plastic waste is currently recycled, while the remaining 85% is usually incinerated to recover thermal energy or landfilled. The hurdles to efficient recycling come from improper management of end-of-life plastic goods. Moreover, the highly heterogeneous nature and versatility of plastic and polymeric materials have led to the development of multilayered materials, composites, blends and many other different species, whose management and/or reprocessing to yield high-value products is extremely challenging. Thus, although these materials are extremely valuable from an industrial point of view, they add a high degree of complexity to the recycling process because each one of them is different from the other, but they cannot be separated efficiently. The aim of the present review is to return a comprehensive overview of environmental and management issues related to the complex and heterogeneous mixture of plastic waste that is generated at the end of the sorting procedures in Italian plastic recycling plants, the so-called ‘Plasmix’. This review lists the difficulties and limitations related to the management of non-recyclable Plasmix and highlights the strategies for the proper, sustainable and valuable use of this plastic waste.

Non-dispersive CO2 separation process using vacuum desorption and ionic liquids as carbon capture and utilization innovative technology

Slowing down climate change requires urgent measures, and consequently, one of the main challenges of the scientific community is to develop innovative technologies to reduce carbon dioxide emissions to the atmosphere. Non-dispersive CO2 absorption using ionic liquids (ILs) as solvent and membrane vacuum regeneration (MVR) as desorption step are considered as a one of the most promising technologies for solvent regeneration in post-combustion CO2 capture and utilization (CCU) since high purity carbon dioxide streams are needed for technical valorization approach. In this work, the chemical binding 1-ethyl-3-methylimidazolium acetate ([emim][Ac]) and the physical solvent 1-ethyl-3-methylimidazolium methyl sulfate ([emim][MS]) have been selected. COSMO based/Aspen Plus methodology has been successfully executed to specify the COSMOSAC property method used in the commercial process simulator (Aspen Plus). Besides, a detailed two-dimensional mathematical model of MVR technology has been validated for the first time with [emim][MS] as a representative of physical ionic liquid solvent. The effect on CO2 desorbed flux and process efficiency have been tested at different operation conditions in order to compare the behavior of chemical and physical absorption based on ionic liquids. Low vacuum pressure and high temperature show a positive influence in the solvent regeneration process, while high liquid flow-rate increases the process performance but also decrease the CO2 desorption. The IL ([emim][Ac]) presented higher MVR performance (92 %) than the IL [emim][MS] (83 %) at the best operational conditions (313 K and 0.04 bar), in which the total energy consumption has been estimated on 0.62 and 0.34 MJe·kgCO2−1, respectively. These results noted the benefit of the MVR technology based on ILs compared to the conventional amino-based high -temperature regeneration process (1.55 MJe·kgCO2−1), presenting a step forward in the substitution of amines. This work provides a valuable tool to help in the decision-making to select the most promising ionic liquids, reducing laboratory efforts and, consequently, experimental costs.

Affinity of Keratin Peptides for Cellulose and Lignin: A Fundamental Study toward Advanced Bio-Based Materials.

Keratin is a potential raw material to meet the growing demand for bio-based materials with special properties. Keratin can be obtained from feathers, a by-product from the poultry industry. One approach for keratin valorization is to use the protein to improve the properties of already existing cellulose and lignin-based materials to meet the requirements for replacing fossil-based plastics. To ensure a successful combination of keratin with lignocellulosic building blocks, keratin must have an affinity to these substrates. Hence, we used quartz crystal microbalance with a dissipation monitoring (QCM-D) technique to get a detailed understanding of the adsorption of keratin peptides onto lignocellulosic substrates and how the morphology of the substrate, pH, ionic strength, and keratin properties affected the adsorption. Keratin was fractionated from feathers with a scalable and environmentally friendly deep eutectic solvent process. The keratin fraction used in the adsorption studies consisted of different sized keratin peptides (about 1–4 kDa), which had adopted a random coil conformation as observed by circular dichroism (CD). Measuring keratin adsorption to different lignocellulosic substrates by QCM-D revealed a significant affinity of keratin peptides for lignin, both as smooth films and in the form of nanoparticles but only a weak interaction between cellulose and keratin. Systematic evaluation of the effect of surface, media, and protein properties enabled us to obtain a deeper understanding of the driving force for adsorption. Both the structure and size of the keratin peptides appeared to play an important role in its adsorption. The keratin–lignin combination is an attractive option for advanced material applications. For improved adsorption on cellulose, modifications of either keratin or cellulose would be required.

Materials challenges and opportunities to address growing micro/nanoplastics pollution: a review of thermochemical upcycling

Micro/nanoplastics have sparked attention in recent years due to their widespread presence in the environment. Currently, several waste valorization approaches are under development in order to upcycle micro/nanoplastics. Thermal conversion technologies such as pyrolysis, gasification, liquefaction, or hydrothermal carbonization can yield high-value solid products, oil, and gases from plastics waste. The common thermal conversion technologies investigated focus on maximizing the production of oil and gases (such as H2 and CH4) for use as fuel. Except for hydrogen, when these products are used to generate energy, the carbon emissions generated are comparable to those produced by traditional fossil fuels. Herein, we present a review of the current efforts to capture and convert plastic waste into valuable products with an emphasis on identifying the need to develop processes specifically for micro/nanoplastics while also preventing the release of CO2 emissions. We identify the development of efficient catalytic materials as a critical research need for achieving economically viable thermochemical conversion of micro/nanoplastics.

A Practical Valorization Approach for Mitigating Textile Fibrous Microplastics in the Environment: Collection of Textile-Processing Waste Microfibers and Direct Reuse in Green Thermal-Insulating and Mechanical-Performing Composite Construction Materials

Microplastic (MP) contamination is an urgent environmental issue to address. Fibrous microplastics (FMPs) are the principal MP type in the air and have already been found in human stool and lung tissues. FMPs are generated from the lifecycle of synthetic and blended textiles and are expected to increase due to fast fashion. Among textile processes, the finishing of fabrics is estimated to generate 5000 t/year of textile waste fibers in Italy, including FMPs. To limit FMPs spread, this paper suggests, for the first time, the direct collection of blended finishing textile waste microfibers and reuse in designing thermal-insulating and mechanical-performing fiber-reinforced cementitious composites (FRCs). The microfibers were thoroughly characterized (size, morphology, composition, and density), and their use in FRCs was additionally evaluated by considering water absorption and release capacity. Untreated, water-saturated, and NaOH-treated microfibers were considered in FRCs up to 4 wt%. Up to a +320% maximum bending load, +715% toughness, −80% linear shrinkage, and double-insulating power of Portland cement were observed by increasing microfiber contents. NaOH-treated and water-saturated microfibers better enhanced toughness and linear shrinkage reduction. Therefore, green and performant composite construction materials were obtained, allowing for the mitigation of more than 4 kg FMPs per ton of cement paste. This is a great result considering the FMP contamination (i.e., 2–8 kg/day fallout in Paris), and that FRCs are promising and shortly-widely used construction materials.

Recent advances in heterogeneous catalytic hydrodeoxygenation of biomass-derived oxygenated furanics mediated by formic acid

The hydrodeoxygenation is a prominent valorization approach to upgrade biomass-derived platform compounds, i.e. furfural (FF) and 5-hydroxymethylfurfural (HMF), into the value-added fuels and chemicals. As a promising alternative to molecular H2, formic acid (HCOOH) has been extensively investigated as a liquid organic hydrogen donor for the transfer hydrogenation of biomass derivatives. In this study, the recent advances in the heterogeneous catalytic HCOOH-mediated hydrodeoxygenation processes of FF and HMF (especially, the hydrogenation of C=O bond and hydrogenolysis of C–O bond) are systematically reviewed by summarizing the heterogeneous catalysts developed and reaction conditions reported in literature. Furthermore, the reaction mechanisms including the individual and combined activations of hydrogen donor (HCOOH) and substrates (FF and HMF) on the catalyst surface are also discussed in order to provide fundamental insights into the associated reaction mechanisms for the future catalyst design. It is believed that this review may serve as a concise guideline on the development of heterogeneous catalysts for the upgradation of biomass-derived oxygenated furanics using HCOOH as the hydrogen donor.

Chemical Composition and Bioactive Antioxidants Obtained by Microwave-Assisted Extraction of Cyperus esculentus L. By-products: A Valorization Approach.

Tiger nut is highly appreciated in the Mediterranean basin by the large number of nutritional advantages offered by a beverage, called “horchata,” which is directly obtained from the tuber of Cyperus esculentus L. However, the current tiger nut harvesting and processing practices generate a large number of residues, mainly a solid by-product after processing and the plant that remains spread out in the fields. In this work the plant residues have been fully characterized to get a clear picture of the possibilities for its valorization to generate products with high added value. Several analytical techniques have been applied to obtain data to assess the real possibilities of these residues in advanced applications in the food, packaging and nutrition sectors. Results on the compositional and elemental analysis, monosaccharide composition, phenolic concentration, and antioxidant capacity were obtained from the dry powder (DP). The high content of α-cellulose (47.2 ± 1.8%) in DP could open new possibilities for these residues as raw material in the production of cellulose nanoentities. Many essential minerals with nutritional interest (Na, Mg, Ca, Mn, Fe, Cu, and Zn) and free sugars (xylose, arabinose, glucose, and galacturonic acid) were identified in the DP making it an interesting source of valuable nutrients. The total carbohydrate content was 171 ± 31 mg gdm–1. In addition, microwave-assisted extraction (MAE) was used to obtain extracts rich in polyphenolic compounds. A Box–Behnken design (BBD) was used, and the optimal extraction conditions predicted by the model were 80°C, 18 min, ethanol concentration 40% (v/v), and solvent volume 77 mL, showing an extraction yield of 2.27 ± 0.09%, TPC value was 136 ± 3 mgGAE 100 gdm–1 and antioxidant capacity by the ABTS method was 8.41 ± 0.09 μmoltrolox gdm–1. Other assays (FRAP and DPPH) were also tested, confirming the high antioxidant capacity of DP extracts. Some polyphenols were identified and quantified: p-coumaric (7.67 ± 0.16 mg 100 gdm–1), ferulic (4.07 ± 0.01 mg 100 gdm–1), sinapinic (0.50 ± 0.01 mg 100 gdm–1) and cinnamic acids (1.10 ± 0.03 mg 100 gdm–1), 4-hydroxybenzaldehyde (1.28 ± 0.06 mg 100 gdm–1), luteolin (1.03 ± 0.01 mg 100 gdm–1), and naringenin (0.60 ± 0.01 mg 100 gdm–1). It can be concluded that C. esculentus L. residues obtained from the tiger nut harvesting and horchata processing could be an important source of high value compounds with potential uses in different industrial sectors, while limiting the environmental hazards associated with the current agricultural practices.

Innovations Toward the Valorization of Plastics Waste

Plastics are an extremely important class of materials that are prevalent in all facets of society; however, their widespread use over time, combined with limited end-of-life strategies, has led to increasing levels of waste accumulation. Although currently considered a burden, plastics waste is potentially an untapped feedstock for numerous chemical and manufacturing processes. In this review, we discuss the state of the art of approaches for valorization of plastics waste from a materials research perspective, including previous efforts to utilize plastics waste and recent innovations that have opportunities to add significant value. Although additional progress is necessary, we present several diverse capabilities and strategies for valorization that, when brought together, address end-of-life challenges for plastics at every stage of design and product consumption. In short, a materials research–based framework offers a unique perspective to address the urgent issues posed by plastics, unlocking the potential of polymers and plastics waste.