Green and Sustainable Chemical Processes

The global proliferation of plastic waste has made the search for sustainable chemical recycling strategies imperative to transition toward a circular bioeconomy. This study presents a dual-valorization approach for polylactic acid (PLA) waste, utilizing it both as a sustainable precursor for g-C₃N₄ catalyst synthesis and as a sacrificial agent for green hydrogen production via photoreforming. Platinum-modified graphitic carbon nitride catalysts were synthesized and evaluated using pure lactic acid and commercial PLA waste under solar-simulated irradiation. Results identified C₃N₄-NaOH-Pt as the most active material, while the simultaneous one-pot depolymerization/photoreforming of macroscopic PLA fragments exhibited a peak H₂ production rate of 1.5 mmol·h⁻¹·g⁻¹, remarkably surpassing both the pure monomer model and pre-depolymerized solutions. This enhanced performance is tentatively attributed to a “controlled release” mechanism that prevents catalyst surface saturation and minimizes light scattering effects inherent to fine powders. The study concludes that maintaining the macroscopic integrity of PLA waste provides a strategic advantage for chemical reforming by eliminating energy-intensive grinding and pretreatment. Future research into diverse operational and chemical parameters, including temperature and base-addition strategies, will be essential for scaling solar-driven upcycling technologies. Full article

To address the common drawbacks of polyamine-based CO₂ absorbents, such as high viscosity and precipitation at high CO₂ loading, a novel liquid–liquid biphasic absorbent composed of triethylenetetramine (TETA), 1-(2-aminoethyl)piperazine (AEP), N,N-dimethylacetamide (DMAC), and H₂O was developed in this study. By comprehensively evaluating CO₂ saturation loading, phase separation behavior, rheological properties of the CO₂-rich phase, precipitation suppression, and desorption–regeneration performance, the optimal absorbent formulation was identified as 20 wt% TETA + 10 wt% AEP + 40 wt% DMAC + 30 wt% H₂O. The optimized system enabled more than 98% of the CO₂ absorption products to be concentrated in the lower phase, which accounted for only 56% of the total liquid volume. Compared with the AEP-free TETA/DMAC/H₂O system, the optimized AEP-modified absorbent effectively eliminated precipitation and reduced the viscosity of the CO₂-rich phase to 62.3 mPa·s, while also improving the desorption behavior and cyclic stability of the system. In addition, ¹³C NMR analysis suggested that the salting-out effect is the main driving force for phase separation, with ionic products preferentially enriched in the aqueous phase to form the CO₂-rich lower phase. AEP contributes to viscosity reduction, precipitation suppression, and enhanced regeneration by weakening carbamate aggregation through steric hindrance and promoting bicarbonate formation. Full article

With the rapid growth of the medicinal cannabis sector, there is a growing concern regarding its environmental impact and sustainability. In recent years, life cycle assessment (LCA) studies on medicinal cannabis cultivation and processing have been conducted since 2021. However, there is a lack of comprehensive LCA studies that include all stages of medicinal cannabis cultivation and processing. In this systematic review, various LCA studies conducted from 2021 to 2025 using the ISO 14040/44 methodology are reviewed and discussed in terms of their goal and scope, life cycle inventory (LCI), life cycle impact assessment (LCIA), and result interpretation. Various environmental impact indicators are considered in this review, such as greenhouse gas emissions, energy demand, water usage, eutrophication, acidification, and resource depletion. All of these impact indicators point to a significant environmental impact of indoor cultivation in terms of greenhouse gas emissions, which vary from 2.3 × 10³ to 5.2 × 10³ kg CO₂ eq kg⁻¹ of dried cannabis product. Nevertheless, it is important to note that this is significantly influenced by regional electricity sources. Low-carbon-based electricity sources, especially hydro-based sources, can reduce emissions to a significant level. Cultivation outdoors presents significantly lower emissions of (60–110 kg CO₂ eq kg⁻¹), but fertilizers and substrates used in cultivation contribute significantly to emissions. Also, outdoor plants use 22.7 L plant⁻¹ d⁻¹ water at peak growth, while indoor plants use 9–11 L plant⁻¹ d⁻¹ water. Improvements in the life cycle of cannabis cultivation can be achieved through renewable energy use, water and fertilizers, substrate use and reuse, and inventories for post-harvesting activities like drying and extraction. Botanical parameters including genotype, planting density, and harvesting frequency are identified as significant but under-characterized determinants of LCA outcomes. Ethical and legal barriers are shown to be structural drivers of the LCA data gap. A SWOT analysis contextualizes the opportunities and constraints of the sector. Future research should focus on cradle-to-grave LCA and incorporate socio-economic factors for sustainability in the medicinal cannabis sector. Full article

Natural plant-based resources are rich in bioactive compounds that offer promising alternatives for developing sustainable, functional textiles. This study focuses on the extraction and application of natural dyes from Gardenia jasminoides as an eco-friendly substitute for conventional synthetic dyes. The dye was extracted using methanol–water (50:50) and ethanol–water (50:50) solvent systems, alongside conventional aqueous extraction, followed by characterization through column chromatography. The characterization of the extracted powders confirmed the presence of gardenia yellow pigments with strong coloration potential. Among the tested extraction methods, ultrasonic-assisted methanol–water extraction (M.W.U.) exhibited the highest dye yield of 29.5%, followed by ethanol–water ultra-sound extraction (E.W.U.) at 24.9%, water ultrasound extraction (W.U.) at 18.35%, and the lowest yield obtained from the water-heater method (W.H.) at 18.25%. The dyed cotton fabrics were tested for color strength (K/S), CIELAB, colorfastness (washing, light, rubbing), and functional properties (antibacterial and vector protection) according to standard operating procedures. The results revealed that an optimal mordant concentration produced the maximum color strength (K/S = 1.7730), with good rubbing (4–5), washing (4–5), and light fastness (5). The dyed fabrics also exhibited excellent antibacterial activity against both Staphylococcus aureus and Escherichia coli, as evaluated by the AATCC 100 test method. For instance, the vector protection property of the cotton dyed fabrics was also excellent, as confirmed by the cage test. Overall, the use of Gardenia jasminoides seed-based natural dye demonstrates not only desirable coloration and functional performance but also significant ecological advantages, reducing chemical pollution and supporting the transition toward environmentally sustainable textile processing. Full article

Soapstock (SS), a by-product of vegetable oil refining, is a promising source of a mixture of mono-, di-, triglycerides, and free fatty acids (MDTG-FFA), a valuable feedstock for biodiesel production. In this study, the selective extraction of MDTG-FFA from SS using green solvents (ethyl acetate, ethyl formate, methyl acetate, isopropyl acetate, and isobutanol) was investigated. Ethyl acetate showed the highest efficiency, allowing the elimination of the phosphatide (PL) precipitation step with acetone. The process optimization was carried out by response surface methodology with central composite design. Statistical analysis confirmed the significance of the obtained models: F-values were 4.55 (p = 0.013) for MDTG-FFA and 9.62 (p = 0.00074) for PL. Regression analysis revealed a good fit of the experimental data with quadratic models for MDTG-FFA and PL, with coefficients of determination (R²) of 0.804 and 0.897, respectively. The optimum extraction parameters were a solvent-to-dry-matter-of-SS ratio 5:1, time 10.2 min, and initial extraction temperature 21.7 °C. Under these conditions, maximum MDTG-FFA yields of 12.6% and 13.4% were achieved for the two batches of SS, respectively, with minimum PL yields of 0.02% and 0.1%. The obtained MDTG-FFA extracts rich in free fatty acids represent a promising feedstock for biodiesel production. The proposed method provides a rational, resource-efficient, and environmentally preferable extraction of valuable components from SS. Full article

The development of effective bone substitutes remains a central goal in regenerative medicine. In this study, lithium-modified bioglass-ceramics based on the 47.5S5 silicate oxide system were synthesized using the sol–gel method, followed by calcination and axial pressing to form cylindrical samples. These materials were sintered at 700 and 800 °C and subsequently examined to evaluate their structural, mechanical, and biological performance. Structural and microstructural analyses confirmed the presence of crystalline phases such as combeite (Na₆Ca₃Si₆O₁₈), NaLiSiO₄, Li₂SiO₃, and calcium silicates, indicating the successful incorporation of lithium within the glass-ceramic network. The bioceramics exhibited improved densification, deformability, and compressive strength with increasing sintering temperature. In vitro degradation in simulated body fluid revealed a consistent increase in mass loss with higher lithium content, suggesting enhanced resorbability linked to lithium oxide. Antibacterial testing indicated moderate antimicrobial activity, with slightly better results observed at higher sintering temperatures. Cell viability assays further supported the materials cytocompatibility. Taken together, these findings suggest that lithium substitution contributes positively to both mechanical robustness and biological behaviour, positioning these ceramics as promising bioresorbable bone substitutes with controlled degradation, suitable for bone tissue engineering where durability, bioactivity, and antimicrobial function are required. Full article

A comprehensive analysis of selected DFT exchange–correlation functionals is presented, focusing on their performance in treating gold nanoclusters and on their known reliability for the description of organic species, energy barriers and dispersion interactions. To distinguish this study from the existing literature, the investigation specifically considers the practical relevance of the chosen functionals in catalytic contexts, with a particular emphasis on their potential applications in nanocatalysis for biomass valorization. Gold clusters containing 4 to 20 atoms were examined, with special attention given to the number of atoms at which the planar-to-three-dimensional-structure switch occurs. The investigation reported in this work would suggest M06 as the best exchange–correlation functional in terms of applicability and overall accuracy for computational studies of catalyzed processes involving gold nanoclusters and organic components. Full article

Rapid, accurate, and sustainable methods for assessing soil properties are essential for environmental management. This study proposes a green analytical approach for the direct determination of soil texture and organic matter using benchtop (1250–2500 nm) and portable (900–1700 nm) near-infrared (NIR) spectrophotometers combined with multivariate calibration. Partial least squares (PLS1 and PLS2) regression models were developed using regional calibration samples and applied to additional samples from the same area. Both individual (PLS1) and simultaneous (PLS2) predictions of clay, sand, silt, and organic matter contents were evaluated. Synergy interval PLS (siPLS) algorithms were used to optimize variable selection. For clay, RMSEP was 2.1% (benchtop) and 2.0% (portable), with RPD values around 2.0. Simultaneous prediction of sand content yielded better results (RPD = 1.3 benchtop; 0.8 portable). Silt prediction showed low accuracy (RPD < 1.0). Organic matter was best predicted by siPLS1 using the benchtop device (RPD = 1.5), followed by portable PLS2 (RPD = 1.2). Benchtop and portable NIR approaches proved satisfactory for direct determination of soil properties. PLS1 models offered greater specificity, while siPLS enhanced accuracy through variable selection. PLS2 models enabled efficient simultaneous predictions. Both devices meet white analytical chemistry principles, aligning performance with sustainability, thus demonstrating that accurate and environmentally responsible soil analysis can be achieved without compromising analytical efficiency. Full article

Ammonia production is a cornerstone of the modern chemical industry, essential for fertilizer manufacturing and increasingly relevant in the energy sector. However, the conventional Haber–Bosch (HB) process is highly energy- and carbon-intensive, contributing significantly to global greenhouse gas emissions, releasing approximately 1.6 tonnes of carbon dioxide for every tonne of ammonia produced. In the context of the ongoing climate crisis, exploring sustainable alternatives that can reduce or even eradicate these emissions is imperative. This review examines the potential of ammonia as a future energy carrier and evaluates the transition to green hydrogen-based HB production. Key technologies for green hydrogen generation are reviewed in conjunction with environmental, energy, and economic considerations. The transition to a green hydrogen-based HB process has been demonstrated to offer significant environmental advantages, potentially reducing carbon emissions by up to eight times compared to the conventional method. Furthermore, the economic viability of this process is particularly pronounced under conditions of low-cost renewable electricity, whether utilizing solid oxide electrolysis cells or proton-exchange membrane electrolyzers. Additionally, two emerging zero-emission, electrochemical routes for ammonia synthesis are analyzed in terms of their methodologies, efficiencies, and economic viability. Promising progress has been made in both direct and indirect nitrogen reduction approaches to ammonia. The indirect lithium-mediated pathway demonstrates the greatest potential, significantly reducing ammonia production costs. Despite existing challenges, particularly related to efficiency, these emerging technologies offer decentralized, electrified pathways for sustainable ammonia production in the future. This study highlights the near-term feasibility of decarbonizing ammonia production through green hydrogen in the HB process, while outlining the long-term potential of electrochemical nitrogen reduction as a sustainable alternative once the technology matures. Full article

Urban solid waste (USW) is a promising alternative source of valuable chemical compounds. It is considered an adsorbent material due to its chemical structure, porosity and electronic charge available to form chemical bonds and can be recovered or transformed for use in bioprocesses and industrial applications. This is the case with cigarette butts (CBs), which consist of thousands of substances that can be chemically converted for various purposes. This work showed high efficiency in the production of cellulose mass from the recycling of CBs, a patented technology in operation at the company Poiato Recicla—SP. The lignin-like solid (LLS)—a material obtained from the recycling of cigarette butts (CBs) by catalytic transfer hydrogenation (CTH), under non-rigorous conditions—showed high efficiency in its conversion into molecules of great interest. In the bio-oil obtained, characterized by analyses such as GCMS and RMN 2D HSQC, a mixture of predominantly hydrocarbons (many of them with cyclic and/or branched chains) was identified in almost all the experiments. This method demonstrates the potential of the TCH process for SSLs and completes the recycling chain designed for CBs, promoting their complete conversion into chemical compounds of greater interest. Full article

The use of natural materials as adsorbents and the environmentally friendly removal of pollutants and azo dyes from water are important topics today. The goal of this research work was to assess the utility of Luffa cylindrica (L. cylindrica) as a natural and non-conventional adsorbent for azo dyes in water on a large scale (2 L). An azo dye (AD) at a concentration of 0.250 g/L was removed from the solution at a rate of 63.07% using 10.0 g/L doses of L. cylindrica, and the maximum adsorption capacity of L. cylindrica was 25.25 mg/g. L. cylindrica desorbed 95.8% of the AD in 0.1 M NaOH. Thermodynamically, the adsorption occurs through pseudo-second-order kinetics and the behaviors adjust better to the Langmuir isotherm. The analysis of variance (p-value < 0.05) shows that the contact time and the concentration of AD significantly influence the adsorption capacity and removal of AD. Few studies have examined the environmentally friendly removal of azo dyes from water using a natural non-conventional adsorbent. Full article

The enzymatic resolution of chiral sofosbuvir precursors is a critical step in producing stereoisomerically pure ProTide drugs, essential for their therapeutic efficacy. In this study, a mutated phosphotriesterase (W131M-PTE) was immobilized onto various polymeric macroporous beads, including commercial immobead 150P (IB), modified (IB-EDA and IB-MTD), and synthetic polyacrylamide (PAM) beads functionalized with glutaraldehyde (PAM-GA) or 1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide (PAM-EDC). The immobilization efficiency, stability, and reusability of the enzyme were systematically evaluated. Among the tested supports, PAM-EDC demonstrated superior performance, retaining high enzymatic activity across multiple cycles and achieving a 92% yield of the (Sp)-diastereomer. The study highlights the potential of immobilized W131M-PTE as a cost-effective and scalable solution for chiral separation in pharmaceutical manufacturing, with implications for broader applications in ProTide drug production. Full article