Environmental Progress & Sustainable Energy最新文献

Coffee is one of the most important agricultural commodities in Brazilian agribusiness. The processing of coffee beans generates large volumes of residues with low environmental sustainability. Converting this biomass into bioethanol is a promising alternative, which requires pretreatment and enzymatic hydrolysis. This study aimed to optimize the hydrolysis of coffee pulp pretreated with 4% sodium hydroxide for ethanol production. Initially, different biomass loadings were evaluated, and 20 g/40 mL (14% w/v, dry basis) was selected due to its significantly higher cellulose-to-glucose conversion (Tukey, p < 0.05). A central composite rotational design (CCRD) assessed the effects of cellulase (1.5–43.5 FPU/g) and β-glucosidase (0–40 CBU/g) concentrations on the release of total sugars, reducing sugars, and glucose. The optimal conditions determined by the design were 25.78 FPU/g cellulase and 28.95 CBU/g β-glucosidase, resulting in an 85% conversion of cellulose to glucose. The central point treatments of the CCRD were used for fermentation with Saccharomyces cerevisiae CAT1 and Kluyveromyces marxianus CCT 4086, yielding ethanol concentrations of 25.63 and 21.71 g/L, respectively. The results demonstrate the technical feasibility of producing fermentable sugars and ethanol from coffee pulp through integrated pretreatment, enzymatic hydrolysis, and fermentation, contributing to waste valorization and sustainable biofuel production.

Eggshell (ES) membranes are rich in proteins consisting of many disulfide bonds and are reducible by various reductants to thiol ligands if adequately treated. This study adopted factorial experiments and response surface design to verify the most critical factors and determine the optimal conditions in eggshell reduction operations. Also, isothermal and kinetic adsorption models were used to demonstrate the metal adsorptive characteristics of the non-reduced and optimally reduced eggshells that adsorbed silver, copper, and chromium in water. Analysis-wise, metals in water were treated by aqua regia digestion and analyzed through inductively coupled plasma atomic emission spectroscopy (ICP-AES). Results revealed that thioglycol (i.e., 2-mercaptoethanol) and reaction time were the two most critical eggshell-modifying factors. Results of the response surface experiments indicated that the optimal eggshell reduction conditions were at the initial reductant concentration and reaction time equal to 9.75 M and 1.9 h, respectively. As for the isothermal metal adsorption using the modified eggshells, it fit the Langmuir model the best with the maximum adsorption capacities (q_m) of silver, copper, and chromium equal to 1.35, 2.09, and 2.39 mmole/g-ES, respectively. Data revealed that the reduced eggshells could completely adsorb silver, copper, and chromium within five hours and adsorbed around 6 and 2.6 times more copper and silver than the unreduced eggshells. These results demonstrate the much better uses of the reduced eggshells than plain eggshells for water metal purification.

The performance of the multi-walled carbon nanotubes (MWCNTs)–calcined otoliths (OLT) composite (MTO) in removing tetrazine (Tatz) from aqueous solution was evaluated and compared with that of calcined otoliths (OLT) alone. To find the ideal sorption conditions for Tatz removal, the effects of key variables, including pH, contact time, adsorbent amount, initial Tatz concentration, and adsorbate temperature, were investigated through batch adsorption trials. The uptake of Tatz by OLT and MTO was dependent on the aforementioned factors of adsorption. The pseudo-second-order model provided the best fit for the kinetic data of OLT and MTO, reflecting a chemisorptive mechanism involving two molecular interactions between Tatz and the active binding sites. The Langmuir and the Freundlich models best described the equilibrium data obtained for both OLT and MTO, respectively. Therefore, MTO exhibited a higher removal efficiency for Tatz, with an adsorption capacity of 58.75 mg g⁻¹, compared to 19.53 mg g⁻¹ for OLT. Therefore, using MTO as a possible sorbent for wastewater and effluent treatment is doable and ought to be investigated further to reduce water pollution.

This study explores the utilization of waste cooking oil (WCO) biodiesel and waste tire-derived pyrolysis oil (PO) as alternative fuels in a diesel engine, with the goal of promoting sustainable waste-to-energy conversion. Biodiesel was synthesized from WCO, while PO was extracted from discarded tires. Four fuel blends (P5B5, P10B10, P15B15, and P20B20) were prepared by mixing equal proportions of WCO and PO with diesel at concentrations of 5%, 10%, 15%, and 20%, respectively. Initial tests revealed a decline in engine performance and an increase in emissions with these blends. To mitigate these effects, 100 ppm titanium dioxide (TiO₂) nanoparticles were added to each blend. The addition of TiO₂ enhanced combustion quality, leading to improved emission profiles and partial recovery of performance parameters. Specifically, TiO₂ enhanced blends exhibited a marginal reduction in brake thermal efficiency (BTE) and a slight increase in brake-specific fuel consumption, but showed significant reductions in hydrocarbon (HC) and carbon monoxide emissions. A moderate increase in nitrogen oxides (NOx) was observed due to higher combustion temperatures and oxygen availability. Among the tested blends, P10B10.TiO₂ and P15B15.TiO₂ offered an optimal balance between performance and emissions. This research promotes sustainable practices by demonstrating the effective conversion of waste materials into valuable energy resources, aligning with the principles of “waste management” and “waste to energy.”

Activated carbon (AC) has garnered widespread attention as a versatile and sustainable material for environmental remediation and industrial applications. This review offers a comprehensive and structured analysis of recent advancements in the synthesis, modification, and application of activated carbon, with an emphasis on sustainable development. The study critically evaluates fabrication techniques—including physical activation, chemical activation, hydrothermal carbonization, and microwave-assisted methods—using renewable precursors such as agricultural residues, industrial by-products, and natural biomass. Comparative insights into physical forms (powdered, granular, pellet, and membrane) and their influence on adsorption efficiency are also presented. The paper explores various chemical, physical, and microwave-assisted modification techniques aimed at enhancing surface area, porosity, and functional selectivity. It highlights the role of pore size distribution (micro-, meso-, and macropores) in adsorption dynamics and explains how surface functionalization, metal doping, and nitrogen/sulfur treatments tailor activated carbon for specific contaminants. Applications span multiple domains, including the removal of dyes, heavy metals, volatile organic compounds (VOCs), pharmaceuticals, and greenhouse gases like CO₂. In addition to mapping out practical applications, the study identifies key benefits such as cost-effectiveness, resource circularity, and regenerability. It also acknowledges prevailing challenges—including environmental concerns associated with chemical activation, material variability, and scale-up limitations. The manuscript integrates emerging trends in green activation, hybrid composites, nanotechnology, and predictive modeling, providing a forward-looking roadmap for researchers and industry practitioners. By aligning technological innovation with environmental sustainability, this work establishes activated carbon as a cornerstone material for future eco-engineered solutions.

This study aims to investigate the photocatalytic process for the removal of methyl red dye from wastewater. To evaluate the structure of the photocatalyst, FTIR, XRD, and SEM analyses were performed. The effect of various parameters such as tin dioxide to graphene oxide ratio, adsorbent dosage, process time, and lamp type on the removal rate of methyl red dye was investigated. After conducting the experiments according to the experimental design order and reviewing the obtained data, the photocatalyst with a ratio of tin dioxide to graphene oxide of 7.5:1 g/g was selected as the optimal photocatalyst. Also, the removal rate of methyl red obtained at photocatalyst doses of 0.04 and 0.06 g/L had equal removal rates, and as a result, the dose of 0.04 g/L was selected as the optimal catalyst dose. The removal rate of 93% of methyl red was obtained as the highest efficiency by tungsten lamp at 60 min. The results showed that at 10 min, 75% of methyl red was removed and by 60 min the slope of the removal curve was very gentle and reached a constant value. Finally, it was determined that the pseudo-second-order kinetic model has better accuracy in matching the experimental data.

Pulping and papermaking black liquor (BL), predominantly produced during the cooking stage of the kraft or soda pulping processes, contains large amounts of organic and inorganic pollutants including lignin, hemicellulose, sodium hydroxide (NaOH), and sodium sulfide (Na₂S). Direct discharge of this BL into the environment can cause severe ecological harm. Traditional alkali recovery processes used for pulping BL not only require significant financial investment but also fail to achieve high-value utilization of resources such as lignin. In the present study, PANI-ZnO particles were first successfully synthesized using the sol–gel method. These particles were then incorporated as fillers to fabricate PANI-ZnO/PES mixed matrix membranes using the non-solvent-induced phase separation (NIPS) technique. In the filtration test with pulping BL, the membrane containing 0.4% PANI-ZnO obtained the highest flux (1.17 L·m⁻²·h⁻¹) and alkali recovery rate (85.71%), while the membrane containing 0.2% PANI-ZnO showed the highest sensitivity to lignin (58.78%) and hemicellulose (28.81%). Although MMM has been used in water treatment, it is still a challenge to use it exclusively in the harsh pulping black liquor treatment environment. In this study, MMM containing PANI-ZnO was designed specifically, and the synergistic effect was used to tolerate the high alkalinity and high organic load of black liquor. At the same time, lignin macromolecules were efficiently intercepted, and the extremely high alkali recovery rate was given priority, which was directly aimed at the core economic demand of black liquor resource recovery, which was significantly different from the traditional research path that only pursued interception rate or flux.

Reduction of human pathogens from wastewater is of great importance to human health. Constructed wetlands (CWs) are environment-friendly systems that are capable of reducing chemical pollution as well as pathogens from wastewater. However, the insufficient knowledge on the removal of human pathogens and fecal indicator bacteria in CWs due to the complexity of removal mechanisms and influencing factors impedes an accurate understanding and optimization design of this eco-sustainable technology, which is necessary for further improvement of CW performance. The pathogen removal process is complex and mainly influenced by hydraulic loading rate and retention time, macrophyte, seasonal variation, substrate and wetland type. The main removal mechanisms include sedimentation and filtration, predation and photoinactivation. Generally, subsurface flow CWs allow a better reduction of pathogens than free water surface flow CWs, whereas hybrid CW systems have the optimal removal performance. Finally, suggestions were provided for improving pathogen removal in CWs.