Sustainable Chemistry

Biochar, produced through the pyrolysis of biomass and green waste, offers significant potential as a soil amendment to enhance soil health and sustainability in agriculture. However, the current Measurement, Reporting, and Verification (MRV) systems for biochar predominantly focus on carbon credits/offsets, neglecting crucial aspects related to its usability and suitability as a soil amendment on agricultural fields. Through an examination of recent findings, this perspective explores the integration of geochemical tracers, functional group (hydroxyl, carboxyl, phenolic, lactonic, etc.) analysis, and nutrient dynamics into MRV procedures/systems to create a more comprehensive framework. By examining the applicability of these indicators, this paper identifies key gaps and proposes a more robust MRV approach. Such a system would not only facilitate better assessment of biochar’s agronomic benefits but also guide its optimal use in various soil types and agricultural practices. Full article

In this study, several professional cleaning products were analyzed for their impact on local air and sewage contamination. The products were first analyzed for their content of potentially harmful ingredients, their biodegradability, and the potential for the mobilization of hazardous substances from the floorings that were cleaned. The contribution of the cleaning products to sewage pollution with environmentally hazardous substances was studied at full scale. All commercially available cleaning products studied were declared to be environmentally friendly (labeled with the EU Ecolabel). However, despite being labeled as “green” products, between 16 and 24 volatile harmful ingredients were identified. An optimized experimental product, produced completely from natural raw materials, also contained several harmful substances originating from the herbal raw materials themselves. During the field study, we identified a range of trace substances in the sewage. Eight of these substances (e.g., p-cymene, butanone, eucalyptol) significantly originated from the cleaning products. Several others may have originated from the cleaning products, but other sources were also possible. The flooring materials that were cleaned contained several harmful substances themselves. The release of some substances (e.g., toluene) into the sewage significantly increased during the cleaning process. Full article

Phosphorus mainly exists in the form of phosphate in water. Excessive phosphorus can cause eutrophication, leading to algae reproduction and the depletion of oxygen in water, destroying aquatic ecology. This study prepared quaternized polyaniline (PN) and quaternized polyaniline with lanthanum hydrate (HLO-PN), and a new nanocomposite for removing phosphate from wastewater was proposed. The results of adsorption experiments show that HLO-PN can effectively remove phosphate in the range of pH 3~7; the maximum adsorption capacity is 92.57 mg/g, and it has excellent anti-interference ability against some common coexisting anions (${\mathrm{F}}^{-},$ ${\mathrm{C}\mathrm{l}}^{-},$ ${\mathrm{NO}}_3^{-},$ ${\mathrm{SO}}_4^{2-}$) other than ${\mathrm{CO}}_3^{2-}$. After five adsorption–desorption cycles, the phosphate adsorption capacity (60 mg/g) was still 74.28% of the initial adsorption capacity (80.85 mg/g), indicating that the HLO-PN nanocomposites had good reusability and recovery of phosphorus. The characterization results show that phosphate adsorption is realized by electrostatic adsorption and ligand exchange. Full article

For a long time, the leather industry has considered the chromium tanning process to be the easiest and fastest way to treat raw hides and transform them into valuable products. In the last few decades, increasing attention has been paid to the potential oxidation of the trivalent chromium in tanned leather. This happens for many reasons, such as the quality of the tanning agent or the adoption of good manufacturing practices. Anyway, the main problem, which is difficult to solve, is the sensibility of the free residual chromium tanned leather, which is high enough for possible harmful activity. Given this scenario, this work proposes a solution to decrease hexavalent chromium formation by using antioxidants during the leather tanning process. In this regard, a screening work was started, to find the worst-case scenario for trivalent chromium oxidation. To do this, commercial tanning products were employed, especially fatliquoring agents, which, in some cases, are the main source that could easily react with ROS (Reactive Oxygen Species) to drive chromium oxidation. After the determination of conditions, different groups of common antioxidants were tested to analyse the antioxidation performances and their possible use in the chromium-based tanning process. The results underline the efficient action of the antioxidants studied, paving the way for some interesting perspectives to limit the drawbacks of chromium tanned leather. Full article

Cross-linked polymers synthesized through inverse vulcanization of unsaturated vegetable oils (biopolymers) were used as matrices for incorporating gentamicin (GEN) to form a biocomposite that can amplify GEN antimicrobial activity against Pseudomonas aeruginosa. Two different biopolymers were synthesized using soybean (PSB) and sunflower (PSF) oils by inverse vulcanization cross-linked with sulfur in a 1:1 weight ratio. The study involves the synthesis and characterization of these biopolymers using FTIR and SEM as well as measurements of density and hydrophobicity. The results reveal the formation of biopolymers, wherein triglyceride molecules undergo cross-linking with sulfur chains through a reaction with the unsaturated groups present in the oil. Additionally, both polymers exhibit a porous structure and display hydrophobic behavior (contact angle higher than 120°). The biopolymers swell more in GEN solution (PSB 127.7% and PSF 174.4%) than in pure water (PSB 88.7% and PSF 109.1%), likely due to hydrophobic interactions. The kinetics of GEN sorption and release within the biopolymer matrices were investigated. The antibacterial efficacy of the resulting biocomposite was observed through the analysis of inhibition growth halos and the assessment of P. aeruginosa viability. A notable enhancement of the growth inhibition halo of GEN (13.1 ± 1.1 mm) compared to encapsulated GEN (PSF-GEN 21.1 ± 1.3 and PSB-GEN 21.45 ± 1.0 mm) is observed. Also, significant bactericidal activity is observed in PSF-GEN and PSB-GEN as a reduction in the number of colonies (CFU/mL), more than 2 log₁₀ compared to control, PSF, and PSB, highlighting the potential of these biopolymers as effective carriers for gentamicin in combating bacterial infections. Full article

The plant-mediated synthesis of therapeutic metal nanoparticles is an intensively exploited field in the last decade. In particular, Salvia officinalis, considered one of these plants, was used in this work to synthesize silver particles. Here, we have used harmless substances to obtain silver particles and common characterization methods for quickly estimating sizes and shapes. Thus, UV–Visible spectroscopy helped us online-monitor and optimize the synthesis of silver particles and estimate the size of metallic particles in the stock solutions. The resulting eco-friendly synthesized silver particles were then separated and re-dispersed in water, to be analyzed by laser light scattering, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) to prove their nanometric size and shape polydispersity. Furthermore, the role of citric acid in stabilizing colloidal solutions of silver nanoparticles was studied. Full article

The aim of this research was to separate the over-the-counter nonsteroidal anti-inflammatory drug (NSAID), ibuprofen, from an aqueous solution using the adsorption method, as this NSAID is one of the most globally consumed. An adsorbent was crafted from the Agave angustifolia bagasse, a byproduct of the bacanora industry (a representative alcoholic beverage of the state of Sonora, in northwestern Mexico). Three bioadsorbents (BCT1, BCT2, and BCT3) were produced via pyrolysis at a temperature of 550 °C, with slight variations in each process for every bioadsorbent. The bioadsorbents achieved material yields of 25.65%, 31.20%, and 38.28% on dry basis respectively. Characterization of the bagasse and adsorbents involved scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The biomass morphology exhibited a cracked surface with holes induced via the bacanora production process, while the surface of the bioadsorbents before ibuprofen adsorption was highly porous, with a substantial surface area. After adsorption, the surface of the bioadsorbents was transformed into a smoother grayish layer. The macromolecules of cellulose, hemicellulose, and lignin were present in the biomass. According to functional groups, cellulose and hemicellulose degraded to form the resulting bioadsorbents, although traces of lignin persisted after the pyrolysis process was applied to the biomass. In an adsorption study, BCT1 and BCT2 bioadsorbents successfully removed 100% of ibuprofen from aqueous solutions with an initial concentration of 62.6 mg/L. In conclusion, the biocarbon derived from Agave angustifolia bagasse exhibited significant potential for removing ibuprofen via adsorption from aqueous solutions. Full article

Ammonia can be considered a relevant compound in the future energy sector, playing a significant role as an energy carrier, storage, or carbon-free fuel. However, the production of this molecule has a high energy demand, and the use of natural gas, which is not free of controversy due to the accidental leakage into the atmosphere produced during extraction and the fact that it is a nonrenewable source, contributes to increasing greenhouse gas emissions. Reducing the process’s energy demand and carbon footprint will be essential to making ammonia a clear alternative for a carbon-free economy. Given the vast research in ammonia production and handling, this gas seems to be the logical step forward in the evolution of the energy sector. However, the current uncertainty in the global market requires cautiousness in decision making. Several factors may impact economic growth and human welfare, thus needing a careful assessment before making any transcendental decisions that could affect worldwide energy prices and raw material availability. Full article

The increasing commercial, industrial, and medical applications of plastics cannot be halted during the coming years. Microplastics are a new class of plastic pollutants which have emerged as escalating environmental threats. The persistence, effects, and removal of MPs present in soil, water, and numerous organisms have become an important research field. However, atmospheric microplastics (AMPs), which are subcategorized into deposited and suspended, remain largely unexplored. This review presents the recent developments and challenges involved in fully understanding suspended and deposited AMPs. The evaluation of indoor suspended MP fibers needs to be critically investigated to understand their implications for human health. Furthermore, the transportation of AMPs to isolated locations, such as cryospheric regions, requires immediate attention. The major challenges associated with AMPs, which have hindered advancement in this field, are inconsistency in the available data, limited knowledge, and the lack of standardized methodologies for the sampling and characterization techniques of AMPs. Full article

Nanochitin, especially in the form of chitin nanowhiskers (ChNWs), represents a significant advance in biopolymer technology due to its high specific surface area, superior tensile strength, and excellent thermal stability. Derived from crustacean waste, which contains 15–40% of chitin, these materials provide a sustainable option that diverts waste from landfills and contributes to environmental conservation. Traditional methods of isolating nanochitin are energy-intensive and generate substantial waste. This study introduces a more sustainable method using inexpensive ionic liquids (ILs) such as [Hmim][HSO₄] and [HN₂₂₂][HSO₄], which bypass the costly and destructive steps of traditional procedures. This study also identified the byproduct in IL-mediated chitin hydrolysis reaction as calcium sulfate dihydrate and presented a solution to circumvent the byproduct formation. The effectiveness of the [HN₂₂₂][HSO₄] IL in producing ChNWs from both purified chitin and crustacean biomass was assessed, showing a high yield and maintaining the purity and structural integrity of chitin, thereby demonstrating a significant reduction in the environmental footprint of ChNW production. Full article

Three ionic liquids (ILs) and three deep eutectic solvents (DESs) with identical counterparts, as well as their aqueous solutions, were prepared for the selective extraction of alginate from Sargassum tenerrimum, a brown seaweed. It was found that the ILs and their hydrated systems were only able to extract alginate from the seaweed directly, while the DESs were not, as confirmed by molecular docking studies. When the quality of the polysaccharide was compared to that produced using the hydrated IL system with the widely used conventional method, it was discovered that the physicochemical and rheological characteristics of the alginate produced using the ILs as solvents were on par with those produced using the conventional method. The ILs can be seen as acceptable alternative solvents for the simple extraction of the polysaccharide straight from the seaweed given the consistency of the extraction procedure used in conventional extraction processes. The hydrated ILs were discovered to be more effective than their non-hydrated counterparts. The yield was also maximized up to 54%, which is much more than that obtained using a traditional approach. Moreover, the ionic liquids can also be recovered and reused for the extraction process. Additionally, any residual material remaining after the extraction process was converted into cellulose, making the process environmentally friendly and sustainable. Full article

Additive manufacturing, commonly referred to as 3D printing, is an exciting and versatile manufacturing technology that has gained traction and interest in both academic and industrial settings. Polymeric materials are essential components in a majority of the feedstocks used across the various 3D printing technologies. As the environmental ramifications of sole or primary reliance on petrochemicals as a resource for industrial polymers continue to manifest themselves on a global scale, a transition to more sustainable bioderived alternatives could offer solutions. In particular, cellulose is promising due to its global abundance, biodegradability, excellent thermal and mechanical properties, and ability to be chemically modified to suit various applications. Traditionally, native cellulose was incorporated in additive manufacturing applications only as a substrate, filler, or reinforcement for other materials because it does not melt or easily dissolve. Now, the exploration of all-cellulose 3D printed materials is invigorated by new liquid processing strategies involving liquid-like slurries, nanocolloids, and advances in direct cellulose solvents that highlight the versatility and desirable properties of this abundant biorenewable photosynthetic feedstock. This review discusses the progress of all-cellulose 3D printing approaches and the associated challenges, with the purpose of promoting future research and development of this important technology for a more sustainable industrial future. Full article

Green carbon-based materials (GCM), i.e., carbon materials produced using renewable biomass or recycled waste, ought to be used to make processes sustainable and carbon-neutral. Carbon nanomaterials, like carbon dots and the nanobichar families, and carbon materials, like activated carbon and biochar substances, are sustainable materials with great potential to be used in different technological applications. In this review, the following four applications were selected, and the works published in the last two years (since 2022) were critically reviewed: agriculture, water treatment, energy management, and carbon dioxide reduction and sequestration. GCM improved the performance of the technological applications under revision and played an important role in the sustainability of the processes, contributing to the mitigation of climate change, by reducing emissions and increasing the sequestration of CO₂eq. Full article

Exploring sustainable approaches to replace petroleum-based chemicals is an ongoing challenge in reducing the carbon footprint. Due to the complexity and percentage variation in nature-generated molecules, which further varies based on geographical origin and the purification protocol adopted, a better isolation strategy for individual components is required. Agrowaste from the cashew industry generates phenolic lipid (cardanol)-rich cashew nutshell liquid (CNSL) and has recently shown extensive commercial utility. Cardanol naturally exists as a mixture of three structurally different components with C₁₅-alkylene chains: monoene, diene, and triene. The separation of these three fractions has been a bottleneck and is crucial for certain structural designs and reproducibility. Herein, we describe the gram-scale purification of cardanol into each component using flash column chromatography within the sustainability framework. The solvent used for elution is recovered and reused after each stage (up to 82%), making it a cost-effective and sustainable purification strategy. This simple purification technique replaces the alternative high-temperature vacuum distillation, which requires substantial energy consumption and poses vacuum fluctuation and maintenance challenges. Three components (monoene 42%, diene 22%, and triene 36%) were isolated with good purity and were fully characterized by ¹H and ¹³C NMR, GC-MS, HPLC, and FTIR spectroscopy. The present work demonstrates that greener and simpler strategies pave the way for the isolation of constituents from nature-sourced biochemicals and unleash the potential of CNSL-derived fractions for high-end applications. Full article

An overview of the latest advances in the design of active catalysts with the ability to promote (photo) Fenton processes in water from a Green Chemistry perspective is discussed herein. A critical evaluation of the most relevant advances has been disclosed, and a brief perspective is presented about what is needed to fill the gap of knowledge in this field. Full article

The current economic development paradigm, which is based on steadily rising resource consumption and pollution emissions, is no longer viable in a world with limited resources and ecological capacity. The “green economy” idea has presented this context with a chance to alter how society handles the interplay between the environmental and economic spheres. The related concept of “green nanotechnology” aims to use nano-innovations within the fields of materials science and engineering to generate products and processes that are economically and ecologically sustainable, enabling society to establish and preserve a green economy. Many different economic sectors are anticipated to be impacted by these applications, including those related to corrosion inhibitor nanofertilizers, nanoremediation, biodegradation, heavy metal detection, biofuel, insecticides and pesticides, and catalytic CO₂ reduction. These innovations might make it possible to use non-traditional water sources safely and to create construction materials that are enabled by nanotechnology, improving living and ecological conditions. Therefore, our aim is to highlight how nanotechnology is being used in the green economy and to present promises for nano-applications in this domain. In the end, it emphasizes how critical it is to attain a truly sustainable advancement in nanotechnology. Full article

The recycling of catalysts has emerged as a key solution to address environmental pollution and the scarcity of natural resources. This dynamic is further reinforced by the growing industrial demand for catalysts and the urgent need to transition to more sustainable production methods. In the context of chemical transformations, the direct reuse of recycled catalysts for chemical applications in particular represents an elegant route towards greener syntheses. In this article, we review recent advancements in the recycling of homogeneous and heterogeneous catalysts since 2020, emphasizing the utilization of waste-derived catalysts for chemical reactions. In particular, we consider three primary sources of waste: electronic waste, spent lithium-ion batteries, and industrial wastewater. For each of these waste streams, different extraction methods are explored for their effectiveness in obtaining catalysts suitable for a broad spectrum of chemical reactions. These presented studies emphasize the potential of recycled catalysts to contribute to a sustainable and waste-efficient future. Full article

The transition towards sustainable and renewable energy sources is imperative in mitigating the environmental impacts of escalating global energy consumption. Methanol, with its versatile applications and potential as a clean energy carrier, a precursor chemical, and a valuable commodity, emerges as a promising solution within the realm of renewable energy technologies. This work explores the integration of electrochemistry with solar power to drive efficient methanol production processes, focusing on electrochemical reduction (ECR) of CO₂ and methane oxidation reaction (MOR) as pathways for methanol synthesis. Through detailed analysis and calculations, we evaluate the thermodynamic limits and realistic solar-to-fuel (STF) efficiencies of ECR and MOR. Our investigation encompasses the characterization of multijunction light absorbers, determination of thermoneutral potentials, and assessment of STF efficiencies under varying conditions. We identify the challenges and opportunities inherent in both ECR and MOR pathways, shedding light on catalyst stability, reaction kinetics, and system optimization, thereby providing insights into the prospects and challenges of solar-driven methanol synthesis, offering a pathway towards a cleaner and more sustainable energy future. Full article