Search Results (259)

This study evaluates the potential use of reclaimed sand from municipal wastewater treatment plants (WWTP), categorized as waste under code 19 08 02, as a full substitute for natural sand in cement mortars. The sand was subjected to alkaline pretreatment using sodium hydroxide (NaOH) at concentrations of 0.5%, 1% and 2% to reduce organic impurities and improve surface cleanliness. All mortar mixes were prepared using CEM I 42.5 R as the binder, maintaining a constant water-to-cement ratio of 0.5. Mechanical testing revealed that mortars produced with 100% WWTP-derived sand, pretreated with 0.5% NaOH, achieved a mean compressive strength of 51.9 MPa and flexural strength of 5.63 MPa after 28 days, nearly equivalent to reference mortars with standardized construction sand (52.7 MPa and 6.64 MPa, respectively). In contrast, untreated WWTP sand resulted in a significant performance reduction, with compressive strength averaging 30.0 MPa and flexural strength ranging from 2.55 to 2.93 MPa. The results demonstrate that low-alkaline pretreatment—particularly with 0.5% NaOH—allows for the effective reuse of WWTP waste sand (code 19 08 02) in cement mortars based on CEM I 42.5 R, achieving performance comparable to conventional materials. Although higher concentrations, such as 2% NaOH, are commonly recommended or required by standards for the removal of organic matter from fine aggregates, the results suggest that lower concentrations (e.g., 0.5%) may offer a better balance between cleaning effectiveness and mechanical performance. Nevertheless, 2% NaOH remains the obligatory reference level in some standard testing protocols for fine aggregate purification. Full article

Developing a more efficient, cleaner, and energy-saving pretreatment process is the primary goal for lignocellulosic biofuels production. This study demonstrated the feasibility of circulating high-concentration acetone–butanol–ethanol (ABE) obtained via in situ product recovery (ISPR) as a pretreatment liquor. Taking ABE solvent separated from pervaporation (PV) and gas stripping (GS) as examples, results indicated that under dilute alkaline (1% NaOH) catalysis, the highly recalcitrant lignocellulosic matrices can be efficiently depolymerized, thereby improving fermentable sugars recovery in saccharification stage and ABE yield in subsequent fermentation stage. Results also revealed delignification of 91.5% (stream from PV) and 94.3% (stream from GS), with total monosaccharides recovery rates of 56.5% and 57.1%, respectively, can be realized when using corn stover as feedstock. Coupled with ABE fermentation, mass balance indicated a maximal 106.6 g of ABE (65.8 g butanol) can be produced from 1 kg of dry corn stover by circulating the GS condensate in pretreatment (the optimized pretreatment conditions were 1% w/v alkali and 160 °C for 1 h). Additionally, technical lignin with low molecular weight and narrow distribution was isolated, which enabled further side-stream valorisation. Therefore, integrating ISPR product circulation with lignocellulosic biobutanol shows strong potential for application under the concept of biorefinery. Full article

In recent years, biofuels and bioenergy derived from algae have gained increasing attention, fueled by the growing demand for renewable energy sources and the urgent need to lower CO₂ emissions. This research examines the generation of bioethanol and biomethane using freshly harvested and sedimented algal biomass. Employing a factorial experimental design, various trials were conducted, with ethanol yield as the primary optimization target. The findings indicated that the sodium hydroxide concentration during pretreatment and the amylase dosage in enzymatic hydrolysis were key parameters influencing the ethanol production efficiency. Under optimized conditions—using 0.3 M NaOH, 25 μL/g starch, and 250 μL/g cellulose—fermentation yielded ethanol concentrations as high as 2.75 ± 0.18 g/L (45.13 ± 2.90%), underscoring the significance of both enzyme loading and alkali treatment. Biomethane potential tests on the residues of fermentation revealed reduced methane yields in comparison with the raw algal feedstock, with a peak value of 198.50 ± 25.57 mL/g volatile solids. The integrated process resulted in a total energy recovery of up to 809.58 kWh per tonne of algal biomass, with biomethane accounting for 87.16% of the total energy output. However, the energy recovered from unprocessed biomass alone was nearly double, indicating a trade-off between sequential valorization steps. A comparison between fresh and dried feedstocks also demonstrated marked differences, largely due to variations in moisture content and biomass composition. Overall, this study highlights the promise of integrated algal biomass utilization as a viable and energy-efficient route for sustainable biofuel production. Full article

Reprocessing lignocellulosic waste to obtain new products for industrial purposes is a vital part of circular economy. This paper reports the cellulase production by newly isolated Bacillus methylotrophicus cultured on lignocellulosic agro-industrial by-products, out of which brewer’s spent grain (BSG) was selected as most beneficial. Plackett–Burman design was used for screening medium components, while Box–Behnken design was further applied to model the impact of the three most influential variables. The maximum approximated cellulase activity was 0.469 U/mL (1 U = 1 µmol of reducing sugars/1 min), at 48.6 g/L substrate, 5.3 g/L ammonium sulfate, pH 6.1. The partially purified cellulase was characterized, which demonstrated broad range of optimal pH (6.5–9.4), temperature (50–60 °C), and sensitivity to metals. Changes in lignin and pentosans content was demonstrated as a result of BSG hydrolysis with a cell-free cellulase preparation. The produced enzyme was used for hydrolysis of various chemically pretreated (NaOH and H₂SO₄) cellulosic substrates, where for reused alkali-pretreated BSG (after microbial enzyme production) the saccharification efficiency was at a level of 25%. The cellulolytic potential of the bacterial strain, along with its resistance to ethanol, present a beneficial combination, potentially applicable to aid saccharification of lignocellulosic by-products for biofuel production. Full article

Unlike other orchids in the Orchidaceae family, Cymbidium goeringii presents significant challenges for in vitro flowering. In this study, through the screening of different basal media, hormone combinations, and other conditions, we developed efficient rhizome regeneration (micropropagation) and in vitro flowering induction systems from protocorm explants of C. goeringii hybrids. To obtain protocorm explants, seeds were pretreated with either NaOH or NaOCl. Our results indicated that NaOH pretreatment enhanced seed germination more effectively than NaOCl, and Knudson C medium proved more suitable for protocorm induction. The resulting protocorms were then used as primary explants for efficient rhizome micropropagation. An orthogonal design identified the optimal combination for rhizome proliferation: 9.0 mg/L 6-BA, 9.0 mg/L NAA, 3.0 mg/L IBA, and 0.1 g/L activated charcoal (Treatment 9), which achieved a proliferation rate of 35.17%. For rhizome differentiation, MS medium supplemented with 10 mg/L 6-BA, 0.1 mg/L NAA, and 0.1 mg/L AgNO₃ (Treatment 6) achieved a 100% differentiation rate and produced 3.93 buds per explant. Building on this optimized micropropagation system, in vitro flowering was induced directly from rhizomes. The most effective medium was MS (1/3N, 3P) supplemented with 9.0 mg/L 6-BA, 0.1 mg/L NAA, and 0.1–0.3 mg/L TDZ (Treatment 6), resulting in a 36% flower bud induction rate and a 16% normal flower bud formation rate. Orthogonal analysis and ANOVA confirmed that 6-BA was the most significant factor influencing floral transition, with the low-nitrogen and high-phosphorus MS (1/3N, 3P) medium also being a key contributor. Consequently, our study has established an efficient rhizome micropropagation system that enables in vitro flowering induction in C. goeringii hybrids within just six months. This represents a substantial 60–80% reduction in the flowering time (from 6–7 years to 1–2 years), compared to the traditional 6–7-year cultivation period. Future work will focus on ex vitro acclimatization, detailed floral-trait validation, and hormone-regime refinement for fast-tracking breeding programs. Full article

This study presents an investigation on the potential of using one-year-old field-stored Medicago sativa (alfalfa) as a raw material for a multi-output biorefinery. The main objective was to fractionate the biomass into valuable components—crude protein, hemicellulose-derived polysaccharides, lignin, and cellulose—and to explore the latter’s suitability in papermaking. To this end, three pretreatment strategies (water, alkaline buffer, and NaOH solution) were applied, followed by soda pulping under varying severity conditions. Both solid and liquid fractions were collected and chemically characterized using FTIR, HPLC, and standardized chemical methods. Water-based pretreatment was most effective for protein extraction, achieving over 40% protein content in precipitated fractions. The harshest pulping conditions (20% NaOH, 160 °C, 60 min) yielded cellulose-rich pulp with high glucan content, while also facilitating lignin and hemicellulose recovery from black liquor. Furthermore, the pulps derived from alfalfa stems were tested for papermaking. When blended with old corrugated cardboard (OCC), the fibers enhanced tensile and burst strength by 35% and 70%, respectively, compared to OCC alone. These findings support the valorization of unexploited alfalfa deposits and suggest a feasible biorefinery approach for protein, fiber, and polymer recovery, aligned with circular economy principles. Full article

Analcime has demonstrated potential for a variety of applications in technology, especially in adsorption and heterogeneous catalysis. In this study, synthetic analcime was investigated by using sea sand as a silica source. Sea sand was first treated with HNO₃ and NaOH. The pretreated sea sand as the silica resource and Al(NO₃)₃ as the aluminum source were used for the hydrothermal synthesis of analcime with different ratios of Si/Al and Na/Si. The products obtained under different conditions were characterized by X-ray diffraction. The results showed that analcime synthesized using acid-treated sea sand was mixed with other impurities, such as quartz and sodalite. Pure analcime was obtained using alkali-treated sea sand as the silica source. The analcime prepared under an optimized synthesis condition was further investigated via SEM, FT-IR, and TG. The particle size of the prepared analcime ranged from 40 to 50 μm. The adsorption ability of analcime was studied, and the Cu²⁺ adsorption process was found to follow a pseudo-second-order kinetic model. Full article

The natural variability and moisture sensitivity of bamboo limit its widespread use in construction applications. To address these challenges, densification and delignification processes have emerged as promising modification techniques. Densification and delignification processes can lead to significant improvements in the physical, mechanical, and chemical properties of solid wood. In this study, a two-step process of delignification and densification was carried out on Dendrocalamus asper bamboo specimens. The objective was to assess whether the optimized parameters of densification for natural bamboo on an open pressing system can be transferred for delignified bamboo. Delignification was achieved using an alkali solution (NaOH and Na₂SO₃) with two different temperature settings (25 °C or 100 °C). The pre-treated samples were dried in one of the two different conditions, either at 100 °C for 24 h or 25 °C for 30 days, resulting in four different groups with an average moisture content ranging from 7 to 10%. The samples were densified to 50% of their original thickness through an open thermo-mechanical press system at 160 °C with a compression rate of 6.7 mm/min and compared to densified bamboo without delignification (reference). The compression stress required to achieve a 50% degree of densification was evaluated, with untreated samples exhibiting an average value close to 17 MPa. Following treatment, the compression stress ranged from 7 to 13.4 MPa, indicating that the exposure to a high pH solution facilitates the densification process. However, a reduction in flexural properties (MOR, LOP, and MOE) was observed on the alkali-treated samples after a three-point bending test. Physical properties (water absorption and thickness swelling) were not altered after delignification. These findings demonstrate that the direct application of a densification process optimized for natural bamboo is not fully effective for chemically modified bamboo, highlighting the need for adjustments. Delignified bamboo showed an increase in free space after chemical treatment, which should be further densified under higher degrees. Full article

Investigating viable processes for the use of lignocellulosic biomass in clean fuels and high-value-added chemical products is essential for sustainable development. Large amounts of lignin are available every year as by-products of the paper and biorefinery industries, causing a series of problems, particularly environmental ones. Its structure and composition make lignin compatible with the concept of sustainability, since it can be used to produce new chemical products with high added value. As such, this study aims to extract lignin from green coconut fiber (LIG), with the subsequent impregnation of a sodium-octanoate-based surfactant (LIG-SUR), and determine its applicability as an adsorbent for removing copper ions from synthetic waste. To this end, the green coconut fiber lignocellulosic biomass was initially subjected to alkaline pre-treatment with 2% (w/v) sodium hydroxide in an autoclave. Next, the surface of the lignin was modified by impregnating it with sodium octanoate, synthesized from the reaction of octanoic acid and NaOH. The physical and chemical traits of the lignin were studied before and after surfactant impregnation, as well as after copper ion adsorption. The lignin was analyzed by X-ray fluorescence (XRF), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The adsorption tests were carried out using lignin pre-treated with surfactant in a batch system, where the effects of pH and adsorbent concentration were investigated. XRF and SEM analyses confirmed surfactant impregnation, with Na₂O partially replaced by CuO after Cu²⁺ adsorption. FTIR analysis revealed shifts in O–H, C–H, C=O, and C=C bands, indicating electrostatic interactions with lignin. Adsorption kinetics followed the pseudo-second-order model, suggesting chemisorption, with equilibrium reached in approximately 10 and 60 min for LIG-SUR and LIG, respectively. The Langmuir model best described the isotherm data, indicating monolayer adsorption. LIG-SUR removed 91.57% of Cu²⁺ and reached a maximum capacity of 30.7 mg·g⁻¹ at 25 °C and a pH of 6. The results of this research showed that pre-treatment with NaOH, followed by impregnation with surfactant, significantly increased the adsorption capacity of copper ions in solution. This technique is a viable and sustainable alternative to the traditional adsorbents used to treat liquid waste. In addition, by using green coconut fiber lignin more efficiently, the research contributes to adding value to this material and strengthening practices in line with the circular economy and environmental preservation. Full article

This study presents the development of a composite film based on low-pressure polyethylene (LPPE) and sunflower husk. The sunflower husk was pretreated with a 4% NaOH solution. Composite films with a thickness of 200 ± 0.20 µm were obtained, containing 40–60 wt.% sunflower husk. The main mechanical properties, water absorption, and surface morphology of the films were analyzed using scanning electron microscopy (SEM). Thermogravimetric (TG) and differential scanning calorimetry (DSC) curves were obtained for sunflower husk, polyethylene, and composite films. The optimal composition of the film components (wt.%) was determined as follows: LPPE—50–55%, sunflower husk—45–50%. The composite film containing 50 wt.% sunflower husk exhibited the following properties: tensile resistance—3.9 ± 0.18 MPa, relative elongation at break—6 ± 0.28%, tensile strain—21 ± 1.02%, modulus of elasticity—108 ± 5.32 MPa, and water absorption over 24 h—2.4%. Full article

The development of environmentally friendly pretreatment processes for spent lithium-ion batteries (LIBs) is crucial for optimizing direct recycling methods. This study explores alternative approaches for recovering active cathode materials from end-of-life LIBs, focusing on environmentally safer options compared to the usually employed toxic solvent N-methyl-pyrrolidone (NMP), using disassembled batteries as test subjects. Various pretreatment methods, including thermal treatment, selective aluminum foil dissolution with a NaOH solution, and the use of eco-friendly solvents such as triethyl phosphate (TEP), are examined on the cathode sheets. The results show that thermal pretreatment combined with TEP provides the most effective approach, achieving a recovery efficiency of 95% while maintaining the morphology and purity of the recovered materials, making them suitable for direct recycling. These methods are further tested on complete battery cells, simulating industrial-scale operations. The TEP treatment proves particularly promising, ensuring high recovery efficiency and preserving the structural integrity of the materials, with a mean particle diameter of approximately 8 µm. Additionally, when applied to cycled batteries, this pretreatment successfully recovers active materials without contamination. This study provides valuable insights into various pretreatment strategies, contributing to the development of a greener, more efficient direct recycling pretreatment process for spent LIBs. Full article

As of today, bacteriological identification and the molecular approach PCR are considered the gold standards for Salmonella spp. detection. However, these methods are time-consuming and costly due to the requirements for enrichment and nucleic acid extraction. In this study, we evaluated the reliability of a developed colorimetric loop-mediated isothermal amplification (cLAMP) assay targeting the hilA gene, using Phenol Red as an amplification indicator. Given that Phenol Red is pH-dependent, and to develop an extraction-free test, we evaluated chicken meat pretreatment and thermal treatment. First, we assessed the reliability of this test using a pure culture of Salmonella spp. and then in 50 chicken samples pretreated with optimal NaOH concentrations under standardized conditions. Samples representing extreme pH values were artificially contaminated and subjected to DNA extraction and a heat-treatment protocol. Serial dilutions of these products served as templates for LAMP reactions. The assay sensitivity was estimated to be around 3.9 CFU/µL of pure bacterial culture. In contrast, in biological samples, we detected up to 10 CFU/µL using DNA extraction, while heat treatment successfully amplified the initial solution and even some dilutions up to 10³ CFU/µL. In conclusion, our cLAMP assay demonstrated good sensitivity and provided clear evidence of its potential for in-field use without relying on prior enrichment steps and DNA extraction. Full article

The effective utilization of nonfood biomass for bioethanol production represents a promising strategy for sustainable energy development. Moreover, limited research has been conducted on broom grass (Thysanolaena latifolia) as a potential feedstock for bioethanol production, particularly regarding the effects of NaOH autoclave pretreatment on its enzymatic digestibility and fermentability. This study optimized sodium hydroxide (NaOH) pretreatment combined with autoclaving to enhance the enzymatic digestibility of broom grass biomass. The effects of NaOH concentration (1–4%) and temperature (110–130 °C) on biomass composition, structural features, and enzymatic hydrolysis were systematically evaluated. Pretreatment with 2% NaOH at 120 °C emerged as optimal, achieving 74.7% lignin removal and 93.2% glucan recovery, thereby significantly improving enzymatic hydrolysis efficiency (88.0%) and glucose recovery (33.3%). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that these improvements were attributed to the increased surface porosity and the selective removal of amorphous components while maintaining cellulose crystallinity. The pretreated biomass hydrolysate exhibited excellent bioethanol production. Fermentation using Saccharomyces cerevisiae TISTR 5339 achieved an 86.4% ethanol conversion rate, yielding 147 g of bioethanol per 1000 g of pretreated biomass and representing a 2.6-fold increase compared to untreated feedstock. These findings demonstrate the potential of the NaOH autoclave pretreatment in enhancing bioethanol production from broom grass biomass, aiding the advancement of sustainable and cost-effective lignocellulosic biorefinery processes. The utilization of broom grass for bioethanol production presents an opportunity to valorize this multifaceted plant and expand its potential beyond its traditional uses. Full article

Arundo donax L. is a plant with great potential as lignocellulosic biomass, being a promising source for the development of biodegradable materials. This study evaluated the effects of different chemical pretreatments (H₂SO₄, NaOH, and NaClO) combined with dry milling on the physicochemical properties of biomass. Pretreatment with NaClO was the most effective in removing lignin, reducing its content to 0.2%, while increasing the cellulose content to 67%. Pretreatment with H₂SO₄, although retaining a higher lignin content (24%), resulted in the greatest reduction in particle size, reaching a mean diameter (Dm) of 44.31 µm after 20 h of milling. Density analysis revealed that the raw samples reached a maximum density of 0.218 g/cm³ after 20 h of milling, with the pretreated samples showing lower densities due to the removal of structural components. Thermal analysis showed mass losses of up to 66.4% for samples pretreated with NaClO after 10 h of milling, indicating significant structural changes and improved thermal stability. Morphological analysis via SEM demonstrated elongated and fine particles, with acid pretreatment resulting in the most pronounced structural changes. These findings highlight the efficiency of combining chemical and physical pretreatments to modify the structure of A. donax L., optimizing its properties for the production of high-performance biodegradable materials. Full article

This study investigates the effects of NaOH pretreatment on the microstructural distribution and biomethane released from Xyris capensis. Xyris capensis was pretreated with NaOH using 1, 2, 3, 4, and 5% w/w concentrations for 60, 45, 30, 20, and 15 min of exposure time, respectively, at a 90 °C autoclave temperature. The impacts of the pretreatment technique on microstructural arrangement, crystallinity, and functional groups were examined with a scanning electron microscope (SEM), X-ray diffraction, and Fourier transform infrared (FTIR), respectively. NaOH-pretreated and untreated feedstocks were digested at the laboratory scale at a mesophilic temperature (37 ± 2 °C) for 35 days for their biomethane potential. It was discovered from the SEM analysis that NaOH pretreatment affects the microstructural arrangement of Xyris capensis, and the sample with the longer exposure time is the most affected. The results of XRD and FTIR also indicated that NaOH pretreatment lowered the crystallinity of the feedstock and significantly influenced the functional groups at varying degrees. Biomethane yield was recorded to be 258.68, 287.80, 304.02, 328.20, 310.20, and 135.06 mL CH₄/gVS_added, representing 91.53, 113.09, 125.10, 143.00, and 129.68% more increases than the untreated feedstock. It was discovered that the optimum biomethane generation was achieved when 4% w/w of NaOH concentration was utilized for 20 min. This study shows that a higher NaOH concentration with a shorter retention time is more suitable for Xyris capensis. This pretreatment method can improve the biomethane yield of Xyris capensis and can be investigated for industrial applications and its use on other lignocellulose feedstocks, especially energy grasses. Full article