ACS Sustainable Resource Management最新文献

The valorization of cellulose- and starch-based wastes has been investigated through a two-step methodology, aiming at the synthesis of amine grafted chars tested as catalysts in the synthesis of cyclic carbonates from diols and dimethyl carbonate. Catalysts were prepared by subjecting the starting material to mild pyrolysis for obtaining biochars, followed by anchoring of 1,6-diamino-hexane on the surface of the char, performed in H₂O. This protocol has been applied to three different pristine polysaccharides (starch, cellulose, and cellulose acetate) and wastes containing the same (post-use starch-based plastics, fir sawdust, and post-use cigarette filters). The success of the derivatization method was confirmed by XPS and elemental analyses. The obtained catalysts were effective and did not show any significant difference in terms of the catalytic activity. Broad investigation on the reaction scope has been conducted on several mono- and disubstituted, aliphatic, and aromatic 1,2-and 1,3-diols, giving carbonates in high yields and selectivity (up to 96% and 99%, respectively). Quantification of the active site density has also been performed, allowing the calculation of TONs, TOFs, and productivity values for each catalyst. The recyclability of the heterogeneous catalysts has also been proved, and characterization of the recycled materials confirmed this behaviour.

Bioenergy possesses the potential to alleviate our energy demands while maintaining renewability and carbon neutrality. The utilization of abundant biomass sources for bioenergy production presents a significant challenge. When considering chemical processes for conversion, the development of effective catalysts becomes imperative as they play a pivotal role in biomass-to-bioenergy/biofuel conversion. In such scenarios, heterogeneous nanoporous materials emerge as crucial components for facilitating catalytic conversion. This perspective provides a comprehensive summary of biomass, including its classification, valorization processes and applications along with recent advancements in various catalytic systems utilized for transforming biomass and its intermediates into renewable energy products. We delved into the diverse classes of heterogeneous catalysts, including metal-based, metal oxide-based, silica based, hybrid catalysts, and organic polymers, highlighting their unique structural and compositional features that influence catalytic activity and selectivity. Furthermore, we discussed the importance of pore structure, surface area, and active site accessibility in enhancing catalytic performance. By examining the advantages and limitations of different catalysts, we provide insights into the rational design and optimization of porous heterogeneous catalysts for efficient and sustainable bioenergy conversion. This perspective serves as a valuable resource for researchers and engineers in the field of renewable energy, seeking to develop innovative catalyst materials for biomass valorization.

A basic kinetic model has been applied to microalgae to predict the growth parameters in Zarrouk Media composition (ZMC) and precipitated chrome tanning effluent (PCTE). The model was fitted with the experimental data of Spirulina cultivation to estimate growth parameters: nutrient adsorption constant (K_a) (h^–1), nutrient desorption constant (K_d) (h^–1), rate of respiration (rR_c)(h^–1), efficiency of bio-synthesis (β) (g g^–1), respiration rate (h^–1)(rR_c), rate of maximum photosynthesis (p_max) (h^–1), coefficient for light-absorption (α) (m² g^–1), photon efficiency (g.μmol^–1 photons^–1) (φ_m), etc. The model suggests a higher nutrient adsorption rate in ZMC (0.75 h^–1) as compared to PCTE (1.40 × 10^–2 h^–1). The rate of respiration of Spirulina decreased due to cultivation in PCTE from 5.36 × 10^–3 to 1.91 × 10^–3 h^–1. The biosynthetic efficiency of Spirulina decreased from 8.72 to 2.002 due to cultivation in PCTE media. The maximum photosynthetic rate h^–1 was slightly higher in ZMC as compared to PCTE media. The model parameter values were lower for Spirulina in PCTE than those in ZMC. Spirulina’s cell density was lower in PCTE compared to ZMC, as the doubling time was increased from 9.97 h^–1 to 31.47 h^–1. Moreover, the optimum pH for growth was also shifted from 9.5 to 10.5. The higher dose of PCTE (Cl^– > 2.96 × 10³ mg L^–1) restricted cell growth. Adding Cr(III) in ZMC has a higher impact on cell growth than Cr(VI). The model parameters with Cr(III) and Cr(VI) also showed a decrease in values except rR_c and β have higher values for Cr(VI) as compared to Cr(III) added ZMC due to the non-interaction of Cr(VI) with algae. The model-predicted cell growth rates closely align with experimental results, with deviations within an ±7% margin. The addition of heavy metals to ZMC disrupts nutrient interactions and transport mechanisms during Spirulina cell growth.

Li-ion batteries (LIBs) are widely used nowadays. Because of their limited lifetimes and resource constraints in manufacturing them, it is essential to develop effective recycling routes to recover their valuable elements. This study focuses on the pyrometallurgical recycling of black mass (BM) from a mixture of different LIBs. In this study, the high-temperature behavior of two types of mixed BM is initially examined. Subsequently, the effect of mechanical activation on the BM reduction kinetics is investigated. Finally, hematite is added to the BM to first be reduced by the excess graphite in the BM and second to form an Fe-based alloy containing Co and Ni. This study demonstrates that mechanical activation does not necessarily affect the kinetics of BM high-temperature behavior. Furthermore, it demonstrates that alloy-making by the addition of hematite is a successful method to simultaneously utilize the graphite in the BM and recover Co and Ni, regardless of the LIB type.

When the sustainability in pyrometallurgical recycling of Li-ion batteries was enhanced, precious metals were recovered through an in situ alloy-making process, with an attempt to decrease CO₂ emissions.

In recent years, contamination of aquatic ecosystems by antibiotics, especially tetracyclines (TCs), has become a significant concern. In this study, we have synthesized reduced graphene oxide (GrGO) using jute leaf extract as a green reducing and stabilizing agent for the reduction of graphene oxide (GO). The GO itself was synthesized from graphite derived from waste dry-cell batteries, making the process simple and cost-effective. We aimed to explore its potential as an adsorbent for the rapid and efficient removal of TCs from aqueous media. Characterization of GO and GrGO was carried out using FTIR, FESEM, EDX, and XRD techniques, revealing the successful reduction of GO to GrGO. The adsorption of TCs by GrGO was performed in a batch of experiments to assess the effect of adsorbent (GrGO) dose, solution pH, contact time, and temperature to find out the optimal condition of adsorption. The quantitative analysis of TCs before and after adsorption was conducted by using liquid chromatography–mass spectrometry (LC-MS/MS). Under optimal conditions, 98% of tetracycline (TEC), 97% of oxytetracycline (OTC), and 97% of chlortetracycline (CTC) were successfully removed from aqueous solutions. The adsorption isotherm of TCs onto GrGO fit well with the Freundlich isotherm model, while the kinetic data were best described by the pseudo-second-order model. The maximum adsorption capacity (q_m) of GrGO for TEC, OTC, and CTC were found to be 22.85, 18.53, and 22.23 mg/g, respectively. Notably, the GrGO adsorbent demonstrated the ability to be reused effectively. Thermodynamic studies confirmed that the adsorption process is spontaneous and endothermic. The rapid and effective removal of these TCs was primarily governed by electrostatic and nonbonding interactions on the surface of GrGO. The findings indicate that green-synthesized GrGO is an effective and promising low-cost adsorbent for the removal of TCs from aqueous solutions.