Search Results (10)

Waste tobacco stems from the tobacco industry were used to obtain activated carbon by thermal conversion and chemical activation with KOH. The aim was to investigate its adsorption ability towards Zn(II), Cd(II), and Pb(II) from aqueous solutions. Fundamental physical and chemical properties were investigated, and the point of zero charge pH was detected. The results showed that the obtained activated carbon was characterized by a high specific surface area, pore volume, and negative surface charge, which could make it an efficient metal adsorbent. In the next step, the optimal adsorption conditions were determined using Central Composite Design. Finally, the adsorption kinetics and thermodynamics were studied. The adsorption rate is very high for Pb(II) and Cd(II), whereas it is noticeably lower for Zn(II). The negative value of Gibbs free energy change (∆G) confirmed that the adsorption process of the tested metal ions is feasible and proceeds spontaneously. The thermodynamics indicate that the adsorption of zinc and lead on the tested carbon is an exothermic process, and for cadmium, this process is endothermic. Full article

A field experiment was conducted in 2018 at Marciano della Chiana (Arezzo, AR, Central Italy) with the main aim of investigating the effect of soil amendment with organic fraction municipal solid waste (OFMSW) compost and legume green manuring (Vicia villosa Roth, cv. villana) on a tobacco crop (dark fire-cured Kentucky type, cv. Foiano) grown under both full (100% of ET_c) and deficit (70% of crop evapotranspiration, ET_c) irrigation. The treatments are hereafter reported as GM (vetch green manuring) and NGM (no vetch green manuring), FI (full irrigation) and DI (deficit irrigation), and C (compost soil amendment) and NC (no compost soil amendment). The following parameters were calculated: (i) yield of the cured product (CLY, Mg ha⁻¹) at a standard moisture content of 19%; (ii) irrigation water use efficiency (IWUE, kg of cured product m⁻³ seasonal irrigation volume), nitrogen (N) agronomic efficiency (NAE, kg of cured product kg⁻¹ mineral N by synthetic fertilizers). Dry biomass accumulated in the stem and leaves (Mg ha⁻¹) was also measured at 25, 57, 74, and 92 days after transplanting (DAT). The N recovery from the different plant parts (kg ha⁻¹) was determined at 57 and 74 DAT. The C/N ratio, NO₃-N (kg ha⁻¹), the soil organic matter (SOM, %), and the soil contents of P₂O₅ and K₂O (mg kg⁻¹) were also analytically determined at 43, 74, and 116 DAT. Water retention measurements were carried out on soil samples at 116 DAT at 0–0.3 and 0.3–0.6 soil depths. Overall, there was a negative effect of both compost amendment and green manuring on yield. Green manuring and compost soil amendment improved soil chemical characteristics (i.e., SOM and C/N), as well as the plant N recovery, the IWUE, and the NAE. They increased the water retention capacity of the soil when the tobacco crop was deficit-irrigated and appeared to be promising practices to support the deficit irrigation strategy, contributing to reaching good agronomic results, although under the conditions of water shortage, and showing synergistic action in those conditions. Full article

Synthesis of the photocatalysts with near-infrared light response usually involves upconversion materials or plasmon-assisted noble metals. Herein, NiTiO₃/TiO₂ was synthesized by using waste tobacco stem-silks as biotemplates and tetra-tert-butyl orthotitanate and nickel nitrate as precursors in a one-pot procedure. NiTiO₃(1.0)/TiO₂(TSS) with a mass percent of Ni 1.0% exhibited very high visible-light photocatalytic efficiency in photodegradation of tetracycline hydrochloride (TC), which is 8.0 and 2.3 times higher than TiO₂ prepared without templates and TiO₂(TSS) prepared without Ni, respectively. Interestingly, NiTiO₃(1.5)/TiO₂(TSS) even exhibited good activity under NIR light (λ = 840~850 nm) without upconversion materials or plasmon-assisted noble metals, which is 2.8 and 2.2 times than TiO₂ prepared without templates and TiO₂(TSS), respectively. The boosting photocatalytic activity has been shown to be attributed to efficient charge separation and transfer across a direct Z-scheme heterojunction between NiTiO₃ and TiO₂ and enhanced light-harvesting ability of special flaky structure reduplicated from tobacco stem-silks. This reported strategy provides a new idea for the multifunctional utilization of waste tobacco stem-silks and the synthesis of novel photocatalysts for the potential application in wastewater treatment. Full article

Titanium dioxide (TiO₂) catalysts are primarily utilized under ultraviolet light, and their potential in industrial applications remains largely untapped. To address this issue, our study uses a one-pot impregnation method to prepare a series of In-TiO₂/TSS(X) (TSS, Tobacco stem silk. X, the molar ratio of In/Ti) catalysts. Among them, the degradation performance of the In-TiO₂/TSS(2.0) material increased from 13.8% for TiO₂ to an impressive 92.9%. By establishing a first-order kinetic model, it was determined that the degradation performance of the In-TiO₂/TSS(2.0) material surpassed that of TiO₂ by a factor of 24. Structural characterization revealed that the introduction of tobacco stem silk templates did not alter the crystal phase of TiO₂ and that the main component of the catalyst remained TiO₂. Not only that, an O–In structure formed on the surface of the TiO₂, leading to a significant increase in the material’s specific surface area. Furthermore, principle tests were conducted, revealing significant enhancements in its light absorption capacity, intensity, and photocurrent density. Through active species trapping experiments, it was observed that, in the photocatalytic degradation process of this catalyst series, holes (h⁺) played the primary role, while the hydroxyl ion (·OH) and superoxide ion (·O²⁻) acted as auxiliary species. Full article

The pyrolysis process is a thermochemical conversion reaction that encompasses an intricate array of simultaneous and competitive reactions occurring in oxygen-depleted conditions. The final products of biomass pyrolysis are bio-oil, biochar, and some gases, with their proportions determined by the pyrolysis reaction conditions and technological pathways. Typically, low-temperature slow pyrolysis (reaction temperature below 500 °C) primarily yields biochar, while high-temperature fast pyrolysis (reaction temperature 700–1100 °C) mainly produces combustible gases. In the case of medium-temperature rapid pyrolysis (reaction temperature around 500–650 °C), conducted at very high heating rates and short vapor residence times (usually less than 1 s), the maximum liquid yield can reach up to 85 wt% (on a wet basis) or achieve 70 wt% (on a dry basis), with bio-oil being the predominant product. By employing the pyrolysis technique, valuable utilization of tobacco stem waste enriched with lignin can be achieved, resulting in the production of desired pyrolysis products such as transportation fuels, bio-oil, and ethanol. The present review focuses on catalytic pyrolysis, encompassing catalytic hydropyrolysis and catalytic co-pyrolysis, and meticulously compares the impact of catalyst structure on product distribution. Initially, we provide a comprehensive overview of the recent pyrolysis mechanism of lignin and tobacco waste. Subsequently, an in-depth analysis is presented, elucidating how to effectively design the catalyst structure to facilitate the efficient conversion of lignin through pyrolysis. Lastly, we delve into other innovative pyrolysis methods, including microwave-assisted and solar-assisted pyrolysis. Full article

In this study, Co-doped TiO₂ was synthesized using waste tobacco stem silk (TSS) as a template via a one-pot impregnation method. These samples were characterized using various physicochemical techniques such as N₂ adsorption/desorption analysis, diffuse reflectance UV–visible spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and electron paramagnetic resonance spectroscopy. The synthesized material was used for the photodegradation of tetracycline hydrochloride (TCH) under visible light (420–800 nm). No strong photodegradation activity was observed for mesoporous TiO₂ synthesized using waste TSS as a template, mesoporous Co-doped TiO₂, or TiO₂. In contrast, Co-doped mesoporous TiO₂ synthesized using waste TSS as a template exhibited significant photocatalytic degradation, with 86% removal of TCH. Moreover, owing to the unique chemical structure of Ti-O-Co, the energy gap of TiO₂ decreased. The edge of the absorption band was redshifted, such that the photoexcitation energy for generating electron–hole pairs decreased. The electron–hole separation efficiency improved, rendering the microstructured biotemplated TiO₂ a much more efficient catalyst for the visible-light degradation of TCH. Full article

Treatment of acid mine drainage (AMD) was successfully demonstrated using tobacco waste (dust and stem) as a metal cation adsorbent, pH modifier and carbon source for sulphate-reducing bacteria (SRB). Synthetic and industrial AMD wastewaters were used in batch adsorption and SRB facilitated bioremediation experiments. Up to absorbent loading of 80 g/L, metal removal increased. However, increases above 160 g/L did not offer a proportional increase. At an adsorbent loading of 80 g/L, the highest metal removals of 38, 41, 31 and 43% for iron, nickel, copper and zinc respectively were achieved. The iron data fitted well to the Langmuir adsorption isotherm while the Sips adsorption isotherm better-described nickel, copper and zinc adsorption to tobacco waste. SRBs used were able to use tobacco waste as a carbon source while reducing sulphates to metal sulphides in acid mine drainage. In the presence of SRBs, metal removals by both adsorption and sulphide precipitation were 95, 97, 70 and 93% for iron, nickel, copper and zinc, respectively. Copper, however, demonstrated lower removal yields in both adsorption and bioremediation. Bioremediation improved acid mine drainage pH by 2.05 units. The exponential decay function could model both the metal and sulphate removal perfectly. It was concluded that tobacco waste can be confidently used as an adsorbent and carbon source for sulphate-reducing bacteria while facilitating AMD biological treatment. Full article

Recycling waste biomass into valuable products (e.g., nanomaterials) is of considerable theoretical and practical significance to achieve future sustainable development. Here, we propose a one-pot hydrothermal synthesis route to convert waste tobacco stems into biomass-based N, S-codoped carbon dots (C−dots) with the assistance of carbon black. Unlike most of the previously reported luminescent C−dots, these biomass-based C−dots showed a satisfactory stability, as well as an excitation-independent fluorescence emission at ~520 nm. Furthermore, they demonstrated a pH-dependent fluorescence emission ability, offering a scaffold to design pH-responsive assays. Moreover, these as-synthesized biomass-based C−dots exhibited a fluorescence response ability toward tetracycline antibiotics (TCs, e.g., TC, CTC, and OTC) through the inner filter effect (IFE), thereby allowing for the establishment a smart analytical platform to sensitively and selectively monitor residual TCs in real environmental water samples. In this study, we explored the conversion of waste tobacco stems into sustainable biomass-based C−dots to develop simple, efficient, label-free, reliable, low-cost, and eco-friendly analytical platforms for environmental pollution traceability analysis, which might provide a novel insight to resolve the ecological and environmental issues derived from waste tobacco stems. Full article

In this study, ferric-loaded magnetic burley tobacco stem biochar (MBTS) was synthesized via pyrolysis to improve the removal of Cr(VI). The results showed that MBTS had an adsorption capacity of 54.92 mg Cr(VI)/g, which was about 14 times higher than raw burley tobacco stem biochar (i.e., 3.84 mg/g). According to the findings obtained, a three-step mechanism of Cr(VI) removal by MBTS was further put forward, i.e., (1) Cr(VI) exchanged with hydroxyl groups on MBTS, (2) the reduction in Cr(VI) to Cr(III) mediated by oxygen-containing groups, and (3) the chelation of produced Cr(III) with the amino groups on MBTS. FTIR spectra further revealed that C-N, C-H, and C=C groups played an important role in Cr(VI) removal. Furthermore, the adsorption equilibrium and kinetics of Cr(VI) on MBTS could better be described by the Langmuir equation and pseudo-second-order rate equation. This study clearly demonstrated that ferric-loaded biochar derived from burley tobacco stems could serve as a cost-effective magnetic adsorbent for the high-efficiency removal of soluble Cr(VI) from wastewater. Tobacco stem-adsorbed Cr(VI) realized a green path for treating waste by waste. Full article

A biennial experiment (2009 and 2010) was conducted at Calvi (Benevento, Southern Italy) to evaluate the effect of compost by organic fraction municipal solid waste (OFMSW), in combination with mineral nitrogen (N) fertilization, on yield and quality of three Dark Fire-cured (Kentucky) tobacco cultivars commonly cultivated at Benevento province (Campania region, Southern Italy). Six N fertilization treatments (N0 = soil N reserves available for plant growth; MIN = 135 kg ha⁻¹ of N applied as mineral fertilizer; C10 = 10 Mg d.w. ha⁻¹ compost; C10N = 10 Mg d.w. ha⁻¹ compost + 50% MIN; C20 = 20 Mg d.w. ha⁻¹ compost; C20N = 20 Mg d.w. ha⁻¹ compost + 50% MIN) were combined with the following cultivars: (i) Foiano, medium early maturing; (ii) Riccio Beneventano (local ecotype), medium maturing; (iii) SKL, medium maturing. Yield of cured leaves (Mg ha⁻¹) and growth components (number of leaves per plant, mean individual leaf area, leaf area per plant, specific leaf weight, stem diameter and height) and color parameters (L*, a*/b*) were measured. Leaf quality traits (nitrates, total N and alkaloids contents, score) and N use efficiency were also determined. The best growth and yield performance was reached in 2010 when plants were taller, developed both stems that were more robust and leaves having greater individual leaf area, and showed a higher leaf area per plant than in the first year. Regardless of the form of applied N (compost, mineral fertilizer, or a combination of both), tobacco plants appeared to be directly and positively influenced by increasing quota of readily available N received by each treatment, which was determined at the beginning of field growth by N soil balance and taking into account the percentage of N supplied by organic (compost) and mineral fertilizers. Results obtained with compost treatments, particularly when combined with mineral fertilizer (at C10N more than C20N), appeared comparable or sometimes better than those of full mineral fertilization although N fertilization by synthetic products was applied at very low doses. Full article