Search Results (244)

Dye-containing wastewater poses environmental risks and requires treatment alternatives that are based on renewable and low-cost materials. This study evaluated saline extracts obtained from walnut shells and eucalyptus bark as biocoagulants for apparent color removal from synthetic wastewater containing methylene blue as a model cationic dye at an initial concentration of 10 mg L⁻¹. The effects of extraction time, extraction pH, and salt concentration were investigated using Response Surface Methodology and a three-factor Box–Behnken design. Apparent color removal was subsequently evaluated at biocoagulant dosages of 0.5, 1.0, and 1.5 mL per 100 mL of synthetic wastewater. Walnut shell and eucalyptus bark extracts were prepared using NaCl and KCl, respectively, and apparent color removal was evaluated after the interaction with the dye. Walnut-shell extracts achieved a maximum apparent color-removal efficiency of 47% after 24 h of extraction at pH 6, using 0.5 M NaCl and a dosage of 1.0 mL per 100 mL. Eucalyptus bark extracts achieved a maximum apparent color-removal efficiency of 48% after 12 h of extraction at pH 7, using 1.0 M KCl and a dosage of 1.5 mL per 100 mL. Although the maximum apparent efficiencies were similar, eucalyptus bark showed greater statistical consistency and better predictive model performance. Both residues demonstrated potential as renewable materials for apparent color removal, particularly as pretreatment agents or components of combined wastewater treatment systems. Full article

Water contamination with surface-active agents, such as sodium lauryl sulfate (SLS), represents a serious environmental concern, driving the need for efficient and low-cost alternative adsorbents as a step toward sustainable waste valorization. In this study, waste biomass derived from plum stones, date stones, and walnut shells was successfully transformed into activated carbons via chemical activation using potassium hydroxide (KOH) at 850 °C with a 1:1 impregnation ratio. The synthesized materials underwent comprehensive physicochemical characterization utilizing TG-DSC, elemental analysis, Boehm titration, SEM, TEM, and nitrogen physisorption (BET), whereas their adsorption performance was evaluated against aqueous SLS solutions across various concentrations. The obtained results reveal a predominantly microporous structure with a high specific surface area, reaching up to 1059.01 m²/g for ACdate. The equilibrium adsorption data were well described by the Langmuir isotherm model, which yielded model-estimated asymptotic adsorption capacities (q_m) of 219.70 mg/g for ACwalnut, 178.25 mg/g for ACdate, and 57.80 mg/g for ACplum. These values represent Langmuir-derived model parameters rather than experimentally attained adsorption capacities within the investigated concentration range. Notably, despite having a lower specific surface area than ACdate, ACwalnut exhibited the highest Langmuir-estimated q_m, which may be associated with its structural balance and well-developed mesoporous network (0.210 cm³/g), facilitating the intraparticle transport of SLS molecules. These findings highlight that high efficiency originates from a synergistic combination of accessible porosity, a mesoporous transport network, hydrophobic character, and specific surface functional groups, demonstrating the exceptional potential of these activated carbons for anionic surfactant wastewater remediation. Full article

Walnuts are commercially important tree nuts whose moisture content (MC) influences quality, shelf life, and post-harvest processing. This study evaluated the potential of low-cost acoustic sensing combined with machine learning for non-destructive MC prediction. Sixty in-shell walnuts were subjected to controlled drying at 40 °C for 26 h, with acoustic recordings and physical measurements collected every two hours. Acoustic signals were processed using Wavelet Soft Threshold Denoising (WSTD), Short-Time Fourier Transform (STFT), and Variational Mode Decomposition (VMD), and features were extracted from the resulting signals. Predictive models included generalized linear models (GLM), random forests (RF), gradient boosting machines (GBM), and Partial Least Squares (PLS) approaches. Following grouped walnut-level validation, the highest MC prediction performance was achieved by the model combining dimensional and acoustic descriptors (RF: R² = 0.836; GBM: R² = 0.826), while the model combining drying time and acoustic descriptors achieved moderate predictive performance (RF: R² = 0.762; GBM: R² = 0.760). Overall, the results provide proof-of-concept evidence that acoustic descriptors may complement physical measurements for non-destructive walnut moisture-content prediction. However, substantially larger independent datasets collected across multiple cultivars, production batches, acquisition conditions, and external validation studies will be required before practical industrial implementation can be considered. Full article

Denitrifying bioreactors are edge-of-field best management practices used to reduce excess nutrients in agricultural drainage. Traditional systems rely on woodchips as both a carbon source and microbial habitat, but woodchip-only bioreactors often exhibit limited nitrate removal, particularly under low temperatures and high flow conditions. This study evaluated nitrogen removal in a multimedia bioreactor under varying environmental conditions. A non-ideal, continuous stirred-tank model was applied to estimate nitrogen removal rates and nitrate removal efficiencies in mesoscale reactors containing walnut-shell biochar, Brotex, and woodchips. Two configurations—woodchip–biochar with and without Brotex—were tested at 4 h and 12 h hydraulic residence times (HRTs) and temperatures from 6 °C to 14.5 °C. Nitrate removal was consistently higher in the non-Brotex treatments. At low temperature, average removal was 15.3% (3.21 g m⁻³ d⁻¹) and 50.5% (3.66 g m⁻³ d⁻¹) for 4 h and 12 h HRTs, respectively. Removal improved at higher temperatures, reaching 54.2% (4.77 g m⁻³ d⁻¹) and 79.7% (7.86 g m⁻³ d⁻¹). These results exceeded many nitrate removal values reported for woodchip-only systems in the literature under similar temperature and hydraulic residence time conditions, indicating that alternative media can enhance performance across a range of flow and temperature conditions, supporting broader application in diverse climates. Full article

The aim of the work is to present a technologically feasible method for processing waste biomass into synthesis gas for further use, namely for the synthesis of bio-methanol, which is considered an important renewable fuel. Walnut shells were tested as lignocellulosic waste. Samples with an operating particle size (0.5–3 mm) were pyrolyzed under well-defined conditions in a sealed pressure reactor, using chromium (III) oxide particles and fine particles as a catalyst. The effect of particle size on the yield and composition of resulting synthesis gas and biochar was tested. It was found that slow, catalyzed pressure pyrolysis at a final temperature of 400 °C provides synthesis gas with a H₂/CO ratio of up to 0.9 or up to 1.8 and biochar (35–39 wt.%) useful as biofuel. These products were analyzed and their use described. The residual product was greywater (25–35 wt.%). Overall, under energy-saving conditions (slow pyrolysis, final temperature of 400 °C), pressure and catalyzed pyrolysis of biomass provide usable products and acceptable residuum. Full article

The growing demand for efficient and sustainable materials for air purification has stimulated interest in activated carbons derived from renewable biomass resources. In this study, activated carbons were prepared from Rice Husk, Wheat Straw, Sawdust, and Walnut shells and systematically investigated as sorbents for toxic gases and volatile organic compounds. The materials were characterized using nitrogen and water vapor sorption isotherms, scanning electron microscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, energy-dispersive X-ray and XPS analysis to evaluate their textural properties, morphology, thermal stability, and surface chemistry. The results showed that the precursor type strongly influences the pore structure and functional group composition of the activated carbons. Wheat straw and Rice Husk-derived activated carbons exhibited the highest total pore volume and a well-developed porous structure, together with a high content of oxygen- and silicon-containing elements. Gas breakthrough experiments with different probes showed that Wheat Straw-derived activated carbon excels in non-polar VOC—cyclohexane removal due to its highly microporous structure. In contrast, Rice Husk-derived activated carbon displays strong affinity toward inorganic gases such as NH₃ and, after urea modification, achieves enhanced performance for SO₂. These results underscore the versatility and practical applicability of carbon materials obtained from plant residues. Full article

Cosmetic formulations containing natural or minimally processed raw materials are prone to microbial contamination, which can compromise product safety and quality. The standard ISO 11930 preservation challenge test employs a predefined set of test microorganisms, which may not adequately represent product-associated contaminants. In the present study, an adapted ISO 11930 preservation challenge test was applied to compare the antimicrobial performance of four preservative systems in an oil-in-water cosmetic formulation. In addition to the five standard reference strains, seven environmental and raw-material-associated microorganisms associated with walnut and apricot kernel shells were included. All preservative-containing formulations fulfilled the required acceptance criteria; however, marked differences in time-dependent antimicrobial activity were observed between preservative systems. Among the tested systems, the formulation containing 0.4% potassium sorbate demonstrated the most rapid and broad-spectrum antimicrobial performance across the expanded microbial panel. In contrast, combinations of potassium sorbate with sodium benzoate and benzyl alcohol showed slower antimicrobial efficacy. In conclusion, this study demonstrates that reliance solely on standard reference microorganisms may underestimate preservation risks in cosmetics that use naturally derived raw materials. The adaptive preservation challenge test is a risk assessment approach for evaluating the microbiological stability of cosmetic formulations with reduced-preservative systems. Full article

In this study, carbon quantum dots (CQDs) were synthesized from various lignocellulosic and hemicellulosic biomass precursors via a semi-hydrothermal torrefaction process, and their structural, optical, colloidal, and photocatalytic properties were systematically investigated. Biomass sources including Oriental thuja cone (Thuja orientalis), sawdust, tea waste, apricot kernel shell, walnut shell, sugar beet pulp, hazelnut residue, soybean residue, and chitosan were used to evaluate the effect of precursor composition on CQDs characteristics. UV–Vis spectroscopy confirmed the formation of CQDs in all samples, exhibiting characteristic π–π* and n–π* transitions, while significant variations in absorption intensity and spectral behavior were observed depending on biomass type. Dynamic light scattering and zeta potential analyses revealed that most CQDs exhibited aggregation tendencies, with limited systems showing improved colloidal stability due to electrostatic and/or steric stabilization. The synthesized CQDs were combined with TiO₂ and their influence on the photocatalytic degradation of Reactive Black 5 under UV irradiation was investigated. Although high decolorization efficiencies (85–98%) were achieved, total organic carbon removal remained lower (2.6–41.4%), indicating incomplete mineralization. The highest mineralization efficiencies were observed for TiO₂ systems modified with sawdust- and thuja-derived CQDs. Overall, the results demonstrate that the photocatalytic performance of CQDs-modified TiO₂ systems is governed not only by optical properties but also by surface functionalization, colloidal stability, and charge carrier dynamics. The findings highlight the critical role of biomass composition in determining CQD properties and provide a comparative framework for designing sustainable nanomaterials for environmental applications. Full article

Accurate monitoring of the leaf area index (LAI) throughout the entire growth cycle of walnut trees using UAV multispectral imagery is essential for digital orchard management. In this study, focusing on the ‘Wen 185’ walnut variety in Xinjiang, we simultaneously acquired UAV multispectral images and ground-measured LAI data during four critical growth stages: expansion, hard shell, oil conversion, and maturity. A total of 25 vegetation indices and 48 texture features derived from the gray-level co-occurrence matrix were extracted. Hybrid feature selection combining linear (Pearson correlation), nonlinear (maximum information coefficient and random forest importance), and multiple consensus strategies was employed to reduce redundancy. LAI prediction models were constructed using four algorithms: Random Forest (RF), Support Vector Machine (SVM), LASSO, and Ridge Regression (RR), with model interpretability enhanced by SHAP analysis. Results showed that the multiple consensus screening reduced feature redundancy by an average of 69.6%. SHAP identified five core features: Redge_750_Mean, NDVI, B_Mean, RENDVI, and G_Homogeneity. Importantly, predictor importance shifted significantly with phenology: texture features dominated during the expansion stage, while red-edge indices (RENDVI and Redge_750_Mean) became predominant during the hard shell and oil conversion stages, effectively mitigating the saturation problem commonly observed in traditional indices such as NDVI within the LAI range of 1.5–5.8 in this study. The hybrid feature subset combining “red-edge spectrum + spatial texture” with the Random Forest algorithm achieved superior performance across all stages, with the RPD value exceeding 2.0 during the oil conversion stage, indicating excellent estimation capability. This study demonstrates that a “quality over quantity” feature selection strategy not only reduces model complexity but also enables high-precision, dynamic LAI monitoring throughout the entire walnut growth cycle, providing a scientific basis for intelligent management of large-scale orchards in arid regions. Full article

Contamination of water bodies by emulsified gasoline hydrocarbons, particularly BTEX compounds (benzene, toluene, ethylbenzene, and xylenes), represents a critical environmental challenge due to their toxicity and resistance to conventional treatment methods. In this study, carbonized biosorbents derived from rice husk (CRH) and walnut shell (CWS) were developed for efficient removal of emulsified gasoline from water. The materials were prepared via carbonization under CO₂ atmosphere (300–800 °C), enabling simultaneous carbonization and activation. Structural and surface properties were characterized using Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray fluorescence spectroscopy (XRF). The results demonstrated a strong dependence of adsorption performance on carbonization temperature, with maximum removal efficiencies of 90.2% (CRH-600) and 96.5% (CWS-700). The superior performance of CWS-700 was associated with its highly developed hierarchical pore structure (up to 670 m² g⁻¹), increased carbon content, and enhanced hydrophobicity. Kinetic studies revealed pseudo-second-order behavior, with equilibrium achieved within 25–30 min at near-neutral pH. Gas chromatographic analysis confirmed the complete removal of BTEX and light hydrocarbons (C1–C9) using CWS-700, highlighting its high selectivity toward aromatic compounds. The adsorption mechanism was attributed to the synergistic effect of micropore filling, hydrophobic interactions, and π-π interactions with aromatic hydrocarbons. The obtained results demonstrate that biomass-derived carbon materials, particularly walnut shell-based sorbents, are promising low-cost candidates for the treatment of complex water systems contaminated with emulsified petroleum hydrocarbons. Full article

The valorization of secondary biomass streams is an important step toward more resource-efficient biorefinery concepts and reduced dependence on fossil-based materials. In this study, agricultural and forest residues, namely Atlas cedar cones, mixed conifer cones, hazelnut shells, walnut shells, coffee silverskin, and cocoa shells, were investigated as feedstocks for producing colloidal lignin particles. Lignin-rich extracts were obtained by Organosolv pretreatment using 60 wt% aqueous ethanol, followed by particle formation through solvent shifting and purification by ultrafiltration. A particular novelty of this work is that highly different feedstocks were processed under identical Organosolv and solvent-shifting conditions, enabling a direct comparison of their suitability for colloidal lignin particle production within one consistent process route. The feedstocks differed markedly in extractive content and chemical profile, as shown by sequential Soxhlet extraction and qualitative GC-MS screening. Despite these differences in extract composition, solvent shifting yielded colloidal lignin particles with largely similar properties. Dynamic light scattering showed hydrodynamic diameters of 65–88 nm immediately after precipitation for all samples except cocoa shell, which formed strong agglomerates. The ultrafiltration step further introduced an industry-relevant downstream purification stage by removing most water-soluble low-molecular-weight compounds before product evaluation. After purification and redispersion, particle sizes ranged from 121 to 389 nm, indicating partial aggregation but overall successful recovery of stable colloidal dispersions. All purified particle suspensions exhibited comparable antioxidant activity in the FRAP (ferric reducing antioxidant power) assay, ranging from 12.3 to 18.4 mg lignin per mg ascorbic acid equivalents. These results demonstrate that even chemically diverse biomass side streams can be converted into purified colloidal lignin suspensions with similar colloidal behavior and functional performance. The findings highlight the potential of low-value agricultural and forest residues as promising raw materials for lignin-based antioxidant and material applications. Full article

Bioadsorbents derived from food waste can not only help reduce the amount of such waste but also demonstrate significant potential for CO₂ capture from both the energy sector and other industries. This study evaluates the feasibility of using bioadsorbents obtained from various types of household biowaste—including black and green coffee grounds, tea grounds, potato peels, walnut shells and green walnut shells—for CO₂ capture from flue gas. The bioadsorbents were produced through a two-step process consisting of carbonization followed by KOH activation. The physicochemical properties of the bioadsorbents were characterized using SEM, FTIR, XRD, TGA and BET techniques. The CO₂ sorption capacity was examined for bioadsorbents and for the original biowaste and the biocarbons obtained after carbonization. Isothermal CO₂ adsorption tests were carried out at 25 °C under 100% CO₂ atmosphere. The influence of porous properties—such as specific surface area, total pore volume, micropore volume and average pore diameter—on the CO₂ sorption capacity was assessed for bioadsorbents, biocarbons and raw biowastes. The results showed that the most effective bioadsorbent for CO₂ capture was derived from spent dark roast coffee grounds, with a sorption capacity of 115.8 mg_CO2/g_A. The favorable sorption performance of this bioadsorbent was attributed to its high specific surface area (1580 m²/g), the largest total pore volume (0.84 cm³/g) and micropore volume (0.5 cm³/g) among the tested materials, as well as an optimal average pore diameter (0.96 nm). Similarly favorable structural properties were observed for the potato peel-derived bioadsorbent (APP—1604 m²/g; 0.65 cm³/g) and the bioadsorbent derived from green walnut shells (AGWS—1376 m²/g; 0.64 cm³/g). Their CO₂ adsorption capacities reached 104.1 mg_CO2/g_A and 73.2 mg_CO2/g_A, respectively, for AGWS and APP. Full article

The safety of drinking water has a significant impact on human life and health, with the common presence of Pb (II) causing harm to human beings. The physical adsorption method is an effective means of removing Pb (II) from water. In this study, three types of biochar were produced through a one-step process using agricultural and forestry wastes (rape straw, bagasse, and walnut shell) as raw materials and KHCO₃ as a co-carbonization agent. The resulting biochar exhibited remarkable adsorption capacities for Pb (II). The biochar prepared via a single carbonization process demonstrates excellent adsorption performance towards Pb (II). The adsorption capacity of bagasse-derived biochar reaches 76.94 mg/g, which is 4.5-fold higher than that of the control. For walnut shell-derived biochar, the adsorption value attains 124.90 mg/g, representing a 7.5-fold enhancement. Notably, rape straw-derived biochar demonstrates the maximum adsorption capacity, up to 265.69 mg/g. Mechanistic analysis reveals that the adsorption of rape straw biochar is dominated by ion exchange, while also being influenced by physical adsorption, coprecipitation, and electrostatic attraction. Intriguingly, in this study, the sole use of KHCO₃ as a co-carbonization agent remarkably increases the specific surface area of the biochar and facilitates the formation of micropores. Without the need for pre-carbonization, this approach substantially boosts the Pb (II) adsorption capacity of the biochar. This one-step carbonization strategy exhibits distinct operational convenience and cost-effectiveness, providing promising materials for the low-cost removal of Pb (II) in natural water bodies and open environments, while also offering a viable technical route for the fabrication of high-performance biochar for heavy metal remediation. Full article

The rational design of oxygen carriers (OCs) is critical for enhancing biomass chemical looping gasification (BCLG) performance. This work systematically investigated the effects of different supports (Al₂O₃, ZrO₂, TiO₂, SiO₂) on the performance of NiFe-based OCs with oxidation and catalytic reforming functions. The gasification reactivity and support-active phase interaction of OCs in both oxidized and reduced states were evaluated. XRD, H₂-TPR, XPS, and SEM techniques were employed to characterize the phase composition, synergistic interactions, and surface morphology. The results showed that NiFeAl exhibited the optimal gasification performance in both oxidized and reduced states, achieving a syngas (H₂ + CO) yield of approximately 1.4 m³/kg (dry walnut shell). NiFeAl featured a higher Fe binding energy, abundant cavity structures, and the uniform dispersion of Ni and Fe on Al₂O₃, which confirm the formation of an appropriately strong Ni-Fe-Al ternary system. In contrast, NiFeZr suffered from the higher CO₂ yield, attributed to the over-oxidation caused by the weak interactions. NiFeTi and NiFeSi had lower syngas yields due to their poor reducibility induced by excessively strong interactions. This work verifies that moderate support-active phase interactions in OCs are optimal for BCLG. Full article

The goal of the present paper is to apply a novel biomimetic design strategy for the analysis, emulation, and technical evaluation of design solutions inspired by the morphogenetic logic of the walnut shell microstructure. The shell consists of specialized cells, called sclereids, which develop protrusions and mechanically interlock with neighboring cells, providing exceptional toughness through increased surface contact. To extract and transfer this biological principle, a generative algorithm was developed using the evolutionary solver Galapagos within the Grasshopper visual programming environment. The algorithm generates protrusions on the interfaces of structural blocks and optimizes their contact surface area while maintaining constant block volume. Additional design constraints, including symmetry and manufacturability considerations, were introduced to improve structural performance and computational efficiency. A series of physical specimens with variations in key geometric parameters, such as protrusion number and height, were fabricated using fused filament fabrication (FFF) with PLA material and evaluated through in-plane and out-of-plane three-point bending tests. The results show that increasing the number of protrusions significantly enhances mechanical performance, while increasing their height improves stiffness and interlocking up to a certain threshold, beyond which structural performance decreases due to stress concentration effects. This behavior can be attributed to improved load transfer and stress distribution across the enlarged interfacial area, as well as progressive mechanical engagement between complementary protrusions. The computational model is in good agreement with the experimental results, confirming the validity of the proposed approach. The study demonstrates that biomimetic optimization of interfacial geometry can enhance the mechanical behavior of interlocking systems and provides a framework for translating biological morphogenetic principles into engineering design applications. Full article