Unlocking the Potential of Tobacco Stalks for the Circular Bioeconomy: Implications on Soil Health

Abstract

Tobacco (Nicotiana tabacum) cultivation generates millions of tons of stalk waste annually. This review explores the potential of tobacco stalks as a renewable resource, emphasizing sustainable applications within a circular economy framework, and highlights the key innovative advances. Composting and biochar production from tobacco residues can substantially enhance soil structure, nutrient availability, microbial activity, and heavy metal immobilization, supporting soil restoration and climate-smart agriculture. With 30–36% cellulose and moderate lignin contents, stalks can be converted into bioenergy, biogas, compost, and biopesticides and enable the production of cellulose derivatives. Despite promising results, challenges remain in nicotine detoxification, process optimization, and industrial scalability. Future research should focus on integrated technologies and life-cycle assessments to fully realize the environmental and economic benefits of tobacco waste valorization.

1. Introduction

Tobacco (Nicotiana tabacum L.) belongs to the family Solanaceae and is a non-food economic crop that grows worldwide. It is cultivated excessively in countries such as China, India, Brazil, and the United States [1]. China processes over two million tons of flue-cured tobacco annually, making it the largest producer and consumer worldwide [2], while in the EU, raw tobacco production accounts for about 3.7% of the world’s total and 7.5% of the world’s marketing [3]. In Europe, Greece ranks second in both tobacco cultivation area and production volume, with nearly 13,000 farmers characterized as tobacco producers, while globally it is the second-largest producer of oriental tobacco [4].

During the process of production, around one million tons of tobacco waste is produced, including most discarded tobacco leaves, stem, and scraps [5,6]. Tobacco leaves are used for producing tobacco of any form (cigarettes, cigars, and pipe tobacco) [7], while tobacco stalks are considered hazardous waste, requiring special treatment to protect human health and the environment. Τhus far, a simple and effective method has not been developed for the complete utilization of tobacco stalks [8]. Hence, a large quantity of tobacco stalks remains unutilized in the fields. About one-quarter of the tobacco stalks are incorporated into the soil by ploughing, whereas most are considered as waste or burned in the field. This phenomenon contributes to both resource wastage and environmental pollution [7]. More specifically, the burning of tobacco stalks releases a significant amount of CO₂ and other harmful gases, further intensifying the greenhouse effect and air pollution problems [9]. In 2022, it was reported that the production of tobacco stalks reached 5.8 million tons [10], yet their potential utilization remains largely unexploited. The management of tobacco waste becomes challenging, considering the fact that the stalks contain a certain amount of bioactive compounds such as nicotine [11]. Therefore, it is essential to develop an effective strategy in order to transform tobacco waste into valuable renewable materials and build effective pretreatment technologies that will remove harmful components (nicotine and addictive and toxic chemicals), and breaking down their complex structure is crucial for realizing the resource utilization of tobacco stalks [12].

Tobacco waste is a significant biomass resource that can be utilized for the production of high-value products [13], provided that it undergoes appropriate modifications to minimize the environmental impact. The high content of organic matter, sugar, and cellulose in tobacco stalks makes them a promising raw material for energy, agriculture-based, and other related industrial applications (Figure 1). The management of tobacco waste becomes challenging because the stalks contain a certain amount of nicotine [1]. Nicotine (C₁₀H₁₄N₂) is the principal alkaloid of tobacco, and although it is synthesized in the roots, it occurs especially in the tobacco leaves (Figure 2), with a range 0.5–8%, depending on the variety and cultivation areas [4,11]. According to European Union regulations [14], if the nicotine concentration in tobacco waste exceeds 500 ppm, it is considered to be toxic. In the literature, there are several studies related to nicotine extraction and/or isolation, with primary emphasis on column chromatography, supercritical water extraction, and ultrasound-assisted extraction techniques [11,15,16]. Recently, Reference [17] proposed an integrated scheme that involves steam sterilization for fractionation, nicotine extraction via salting-out for incorporation into nicotine-based products, and subsequent utilization of solid residues through composting or energy recovery. This dual pathway reduces environmental impacts and improves economic viability, aligning with multiple Sustainable Development Goals by promoting resource efficiency, reducing greenhouse gas emissions, and protecting public health.

The objective of this review, after a systematic literature search through scientific databases (Scopus and Google Scholar), is to critically evaluate the potential of tobacco stalks as a renewable resource within a circular bioeconomy framework. Specifically, it aims to (i) analyze the chemical composition and suitability of stalks for soil fertility and remediation, (ii) assess their applications in bioenergy generation, (iii) explore their role in biopesticide development and cellulose synthesis, and (iv) identify technological challenges, environmental implications, and future research directions for sustainable valorization.

2. Characteristics of Tobacco Stalks’ Lignocellulosic Fraction

Tobacco stalks are mainly composed of three components—cellulose, hemicellulose, and lignin—and these components provide them with a high potential for utilization [18,19,20]. Based on the data presented in

Table 1. Chemical composition of tobacco stalks (%, dry basis).

Cellulose (%)	Hemicellulose (%)	Lignin (%)	Reference
41.30	32.00	21.00	[21]
38.53	ND	22.47	[22]
35.45	43.90	18.16	[23]
56.60	11.80	14.97	[24]

, the composition of tobacco stalks varies across studies, with cellulose ranging from 35.45% to 56.60%, hemicellulose from 11.80% to 43.9%, and lignin from 14.97% to 22.47% [21,22,23,24]. It is also reported [25] that stalks of large leaf tobacco plants showed an average of 30.50% to 34.30% of cellulose, while in Virginia, tobacco cellulose reached 35.3% [7]. Due to their high concentration of cellulose, they represent a valuable secondary raw material for specific industrial areas where cellulose is the main ingredient.

Cellulose is a natural polysaccharide with abundance on earth and has been widely utilized in various industrial applications [26,27] such as paper, cardboard, textile, cotton, flax, and many other plant-based fiber industries [25]. Tobacco stalks are viable for conversion into cellulosic products such as ethanol and cellulose-based polymers due to high cellulose content and relatively low lignin. On the other hand, hemicellulose represents the second most common heterogeneous branched polymer in tobacco stalks [28]. It is composed of several components, including pentoses and hexoses [10,29]. Hemicellulose is a branched, acetylated, amorphous polysaccharide that lacks crystallinity and is therefore more easily degradable. Despite this, it acts as a physical barrier that limits the decomposition of cellulose by cellulase enzymes [30]. Cellulose hydrolysis efficiency can be improved by increasing enzyme loading or by applying pretreatments, such as steam hydrolysis or acid pretreatment, to remove hemicellulose [31].

Lignin is an amorphous polyphenolic polymer, and its structure is recalcitrant to degradation [32,33]. In tobacco stalks, lignin typically comprises three types of methoxylated phenyl propanoid monomers [34]. Lignin serves as a glue in the cell wall, surrounding the cellulose and hemicellulose fibers, providing mechanical strength, supporting the formation of vascular tissues, facilitating nutrient transport, and enhancing resistance to microbial activity. Its phenolic structure occupies the spaces between the polysaccharides, reducing the accessibility of cellulase enzymes to cellulose [30]. Alkaline treatment can assist in the removal of lignin and boost the efficiency of the process, given that it exposes the crystalline cellulose and offers enhanced access to cell walls while producing nitrocellulose [35].

ND: not determined.

3. Tobacco Waste as Agriculture Resource

3.1. Compost of Tobacco Residues

Soil health is a key factor in safe cultivation and the production of goods and an expression of decontamination or proper management of emerging pollutants that burden the soil [36]. In recent years, composting tobacco waste has emerged as a particularly effective and environmentally friendly method converting it into stable organic matter of high agronomic value. Tobacco residues, especially stems and leaves, are characterized by a high content of organic carbon, nitrogen, and secondary metabolites, making them a suitable raw material for biological treatment through aerobic degradation [37]. The systematic review by [38] shows that composting tobacco waste leads to a significant reduction in toxic and phytotoxic components, such as nicotine, phenolics, and certain alkaloids, through microbial degradation and oxidation. Meanwhile, there has been an increase in the amount of stabilized humus and available macronutrients (N, P, and K), which boosts the fertilizer value of the final compost [39].

Humification contributes to the creation of stable organic compounds, which improve soil structure, increase aggregate stability, and enhance water and nutrient retention capacity while limiting losses through leaching. In terms of physical properties, incorporating tobacco waste compost into the soil leads to a reduction in apparent density, an increase in total porosity, and an improvement in air permeability and hydraulic conductivity [40]. These changes provide a more favorable environment for root system development and soil microorganism activity, contributing to the overall functionality of the soil ecosystem. In addition, increased moisture retention capacity is particularly critical in areas with intense dry and hot conditions, as it enhances crop resilience to water stress and extreme weather events. The incorporation of tobacco waste with lignocellulosic materials such as bark and straw in fields has been reported to enhance soil nutrient status and significantly improve maize yields [41]. Similarly, composting tobacco waste alone or in combination with agro-industrial by-products, including grape pomace and olive pomace, under Turkish conditions has demonstrated increased microbial activity and efficient organic matter decomposition. These processes resulted in the production of mature compost with improved agronomic properties, alongside the effective degradation and elimination of nicotine-associated phytotoxicity [40]. Furthermore, the application of composted tobacco waste has been shown to significantly increase lettuce yield and nutrient uptake, performing as well as or better than farmyard manure [42].

Research conducted by [43] on the co-composting of fresh tobacco leaves with soil showed that the direct incorporation of tobacco residues accelerates the decomposition processes of organic matter, increasing microbial respiration, microbial biomass, and enzymatic activity. The enhancement of microbial activity is directly related to the improvement of the biogeochemical cycles of nitrogen, phosphorus, and carbon, leading to increased mineralization and better availability of nutrients for plants. At the same time, increased soil biodiversity enhances the ecological stability of the system and limits the growth of pathogens through competitive and competitive–antibiotic mechanisms. Long-term incorporation of tobacco stalks into fields in China [44] offered persistent soil acidification and increase of nitrogen availability and organic carbon content. These inputs resulted not only in higher and optimum leaf yield but also greater profitability for farmers. Overall, this study proved that tobacco stalks compost emerges as a sustainable, cost-effective, and viable eco-friendly alternative to conventional organic fertilizers.

In 2020, Reference [45] demonstrated that composting tobacco waste with industrial effluents significantly decreased nicotine and heavy metal concentrations, while the resulting compost exhibited balanced nitrogen, phosphorus, and potassium levels within the maximum limits for agricultural use. Similarly, when tobacco residues were composted with wood chips and animal manures, a significant reduction in nicotine content was achieved, from 12,180 mg/kg to 160 mg/kg, accompanied by improved crop productivity [46]. Moreover, composting blends of tobacco residues with vegetable waste, combined with biofortification using Brevibacillus brevis, has been shown to enhance the breakdown of toxic compounds and produce nutrient-rich compost suitable for use as an organic fertilizer in agricultural systems [47].

As a soil fertility resource, tobacco stalks provide a source of essential nutrients, particularly potassium and nitrogen, which are released gradually during decomposition or composting. Their incorporation can partially substitute mineral fertilizers, support long-term soil fertility, and reduce dependence on external inputs [48]. Studies have shown that composted tobacco residues enhance soil microbial biomass, enzyme activities, and nutrient availability, thereby improving nutrient cycling efficiency and crop nutrient uptake [49]. These treatments align with the requirements of green agriculture and also reduces the production cost of biofertilizers while allowing for the development of specialized formulations tailored to different crop varieties [50].

Increased biological activity and improved soil organic status are directly linked to enhanced soil fertility, which is a key indicator of soil health. Fertility is not limited solely to the availability of nutrients but instead reflects a set of physicochemical and microbiological properties, such as structure, regulatory capacity, biological activity, and the self-regulating capacity of the soil system. As [51] points out, the simultaneous improvement of physical, chemical, and biological indicators signals an upgrade in soil quality, which is fundamental to sustainable agricultural production and environmental protection. From this perspective, tobacco waste composting is not just a waste management method but a comprehensive tool for restoring and enhancing soil health in the context of the circular economy and agroecology.

3.2. Tobacco Stalk Biochar

Tobacco stalk pyrolysis for biochar production is one of the most studied and promising applications for the utilization of tobacco residues in the context of sustainable agriculture and the circular economy [52]. Through thermal decomposition and pyrolysis, tobacco waste is converted into tar, bio-oil, and biochar [8]. The tar fraction contains high-value chemicals such as nicotine, offering economic opportunities and further extraction or upgrading. Meanwhile, biochar serves as precursor for biochar-based fertilizers, characterized by a highly porous structure, large specific surface area, increased cation exchange capacity, and chemical stability, which make it valuable as a soil conditioner and carbon sequestration agent in the soil [53]. The porous architecture of biochar creates an extensive network of micro- and mesopores, which acts as a “refuge” for microorganisms and as a reservoir for water and nutrients. The large specific surface area favors the adsorption of inorganic and organic ions, reducing nutrient losses through leaching and enhancing their availability to the rhizosphere. At the same time, the high aromatic carbon content makes biochar particularly resistant to biological degradation, contributing to the long-term storage of organic carbon in the soil and reducing CO₂ emissions into the atmosphere [54,55].

3.2.1. Agronomic Utilization

In terms of agronomy, Reference [56] demonstrated that the application of biochar derived from tobacco stems to light sandy soils led to a statistically significant increase in the yield of tobacco, as well as an improvement in the efficiency of nutrient use (N, P, and K). At the same time, an increase in the Carbon Management Index was recorded, indicating improved organic matter quality and enhanced functional stability of the soil system. These findings highlight the dual role of biochar, both as a means of increasing productivity and as a tool for climate mitigation through carbon sequestration and stabilization in the soil.

Beyond its chemical and biological effects, biochar from tobacco stems significantly improves the physical properties of the soil, functions as a slow-release fertilizer carrier, and enhances nutrient availability through its high ion adsorption and exchange capacity [54,57,58]. Its incorporation leads to a reduction in apparent density, an increase in total porosity, and an improvement in the structural stability of aggregates. The improved structure facilitates root system development, enhances air permeability, and increases soil permeability, reducing the risk of surface runoff and erosion [59]. In addition, the increased moisture retention capacity, attributed to the spongy structure of biochar, is particularly critical for soil resilience under conditions of water stress and prolonged drought, which are expected to intensify in the context of climate change.

Ecologically, biochar acts as a soil pH regulator, reducing acidity in acidic soils and improving the availability of essential cations such as Ca²⁺, Mg²⁺, and K⁺ [60]. This regulatory capacity contributes to the creation of a more favorable chemical environment for plants and microorganisms, enhancing microbial activity and the biogeochemical functionality of the soil [61,62]. At the same time, it has been documented that biochar can bind pollutants and heavy metals, limit their bioavailability, and protect the soil ecosystem. Overall, biochar production and application from tobacco stems constitutes a comprehensive agricultural residue management strategy that combines soil fertility improvement with soil structure and water capacity enhancement, supporting microbial activity and long-term carbon sequestration. This approach is fully aligned with the principles of agroecology and the circular economy, transforming tobacco stems from agricultural waste into a valuable resource for restoring and maintaining soil health [63].

3.2.2. Remediation of Heavy Metal-Contaminated Soils

Among the most significant advantages of biochar from tobacco stems is its ability to bind heavy metals. Reference [64] showed that tobacco stem biochar can effectively bind cadmium (Cd), reduce its bioavailability, and lead to increased tobacco productivity. Similarly, the field study by [65] demonstrated a significant reduction in Cd and Cu accumulation in the edible parts of vegetables after the application of biochar from tobacco waste, which has direct implications for food safety and human health. At a more advanced level, Reference [66] developed tobacco stem biochar modified with nano-hydroxyapatite, which exhibited increased Cd adsorption capacity through surface and chemical interactions. This approach opens new prospects for targeted soil decontamination, further enhancing the role of tobacco stems as a tool for restoring soil health.

The high ability of tobacco to accumulate heavy metals positions tobacco crops both as an environmental concern and as a potential phytoremediation agent. This characteristic has led to its application in remediating soils contaminated with Cd and other metals [67]. Conventional remediation strategies for Cd-contaminated soils include physical, chemical, and biological approaches; among these, in situ chemical immobilization is considered one of the most practical and efficient techniques due to its simplicity and high effectiveness in reducing metal bioavailability [68]. However, recent research on heavy metal mitigation and accumulation indicates that assessing soil contamination based solely on their total amount is insufficient. The environmental risk assessment now relies primarily on metal speciation and bioavailable fractions [59,69]. Materials such as phosphates, lime, and metal oxides have been developed for Cd immobilization, but challenges such as high energy consumption and limited duration of effectiveness remain [70,71,72].

Altering biomass from tobacco stems with nano-hydroxyapatite (nHAP) is an innovative way to boost the ability of soil to lock in heavy metals, with the main goal being to reduce the bioavailability of heavy metals in the environment. nHAP is an advanced and highly innovative approach to enhancing the ability to immobilize heavy metals in soil, with the main objective of reducing the bioavailability and toxicity of cadmium. The study by [66] systematically investigated the interfacial adsorption behavior and Cd binding mechanisms of nHAP-modified tobacco stem biochar, demonstrating that this composite structure exhibits significantly higher adsorption capacity compared to unmodified biochar. Nano-hydroxyapatite, a calcium phosphate with high biocompatibility and strong affinity for heavy metals, provides biochar with additional active adsorption sites and enhanced chemical reactivity. Its incorporation into the surface and pores of biochar leads to the creation of a composite material with increased specific surface area, improved porous structure, and high density of functional groups (H and PO₄³⁻), which facilitate interfacial interactions with Cd²⁺ ions.

Adding organic compounds and biochar from tobacco stems really changes the structure and function of the soil microbial community, which is a key regulator of biogeochemical processes in the soil. The increase in microbial biomass, diversity, and enzymatic activity following the application of such soil-improving materials has been associated with enhanced carbon, nitrogen, and phosphorus cycles, leading to faster decomposition of organic matter, increased mineralization, and improved nutrient availability for plants. Microorganisms exploit the organic substrates and porous surfaces of biochar as a source of energy and shelter, which promotes colonization, biofilm development, and the establishment of functionally active microbial populations [63].

Table 2. Impact of tobacco waste (TW) use and related strategies on soil health and fertility.

Method/Application	Effects on Soil Health	References
Sustainable TW management methods—recycling and upcycling (thermochemical/biological methods))	Waste reduction, resource conservation, nicotine recycling, and biochar/fertilizer production—circular economy framework	[38]
Field trial with tobacco stalk compost via organic fertilizer	Raised pH, lower EC, increased SOC, improved N availability, amd enhanced microbial diversity	[44]
Modified biochar from TW using hydroxyapatite for Cd engagement	High Cd adsorption (13.17–14.50 mg/g), using mainly adsorption and precipitation mechanisms	[66]
In situ application of biochar from TW in legumes and flowers	5–10 t/ha TW reduced bioavailable Cd and Cu in soil, reduced metal accumulation in edible parts; increased biomass in chrysanthemum	[65]
Residues + vegetable waste and biofortification	Enhanced detoxification and nutrient-rich compost	[46]
Biochar from tobacco stems + inorganic fertilizers in light Alfisol	One t/ha biochar significantly increased N and K utilization, improving the Carbon Management Index	[56]
Composting fresh tobacco residues	Reduction in nicotine, increase of available N and K, and increase in beneficial microbes	[43]
Tobacco stalk conversion to biochar (TS-biochar)	Increased soil pH (5.21 → 7.39), reduced exchangeable Cd, and improved biomass and photosynthesis	[64]
TW composting with effluents	Reduced nicotine/metals and balanced macronutrients	[45]
TW composting in comparison with manure	Increase lettuce yield and nutrient content (N, P, K, Ca, Mg, Fe, Zn, and Mn)	[42]
TW + bark/straw	Enriched nutrients and improved crop response	[41]
TW compost blends with olive and grape pomace	Nicotine degraded, nutrient levels (N–P–K) increased, organic carbon and C:N ratio decreased, electrical conductivity reduced, and effective detoxification and maturation of tobacco waste compost after 4 months	[40]
TW compost with wood chips/manure	Major nicotine reduction and improved productivity	[46]
Biochar properties for heavy metal stabilization	Alkalinity and surface charge improve soil pH and reduce toxicity	[60]
Biochar as soil amendment	Enhances nutrient availability, microbial activity, and soil fertility	[54,57,58,61,62,63]

summarizes the above research data, underlining the fact that tobacco stems are a valuable resource for improving soil quality and health. According to [51], specific indicators are used to assess soil quality, focusing on changes in its physical, chemical, and biological properties after the addition of low-cost materials. Tobacco stems, through processes such as composting and biochar production, can contribute significantly to improving the physical, chemical, and biological properties of the soil, as well as reducing heavy metal pollution

4. Τοbacco Waste as Source of Biopesticides

Tobacco waste has a potential role in the production of biopesticides mainly due to the presence of nicotine [73], which acts on the insect nervous system by disrupting neurotransmission, leading to paralysis and death. This mode of action offers broad-spectrum efficacy against a wide range of agricultural and storage pests, including aphids, caterpillars, beetles, and mites [74,75].

Traditional applications include tobacco derived extracts, decoctions, and fermented solutions, which have shown significant efficacy against pests such as aphids, caterpillars, and mosquito larvae particularly in small-scale and organic farming systems [76]. More recently, advances in extraction technologies have further enhanced the biopesticidal potential of tobacco waste. Modern green extraction techniques like ultrasound extraction [77], microwave-assisted extraction, and supercritical CO₂ extraction offer faster, more efficient, and more environmentally friendly ways to recover nicotine and other bioactive compounds [11].

Despite these advantages, the high toxicity of nicotine necessitates careful handling, precise dosing, and thorough environmental risk assessment to minimize adverse effects on non-target organisms, beneficial insects, and human health [78]. Although since 2010, in the EU, nicotine is not approved for use as a plant protection product [79], these considerations highlight the importance of developing controlled formulations and integrated pest management (IPM) strategies when deploying tobacco-derived biopesticides.

An innovative and sustainable advancement in this field involves integrating the insecticidal properties of tobacco nicotine with microbial biocontrol agents, particularly Bacillus thuringiensis (Bt). More specific, tobacco waste contains nutrients that can support Bt spore and crystal-protein production [80]. Bt shows strong insecticidal activity against tobacco beetle larvae and holds significant potential for controlling storage-related tobacco pests. The variety of bioactive compounds of tobacco waste, such as alkaloids and essential oils, can serve as effective substrates for cultivating Bt, and notably, Bt has also been naturally identified on tobacco leaf surfaces, further supporting its compatibility with tobacco-based pest control systems [81].

5. Tobacco Waste as Energy Source

Tobacco stems, as a by-product of tobacco cultivation, are produced in large quantities and often remain unused or are disposed of in ways that harm the environment. However, tobacco waste has emerged as a promising alternative to conventional energy sources due to its versatility in producing various fuels, including bio-coal, bio-oil, biogas, bioethanol, and activated carbon (Figure 3).

Bio-coal and bio-pellets produced from tobacco stalks can serve as alternative fuels to coal, while liquid smoke can be utilized as a replacement for chemical pesticides [82] and shows potential in soil remediation. Their high surface area and functional groups favor the sorption and immobilization of heavy metals and organic contaminants, thereby reducing pollutant bioavailability and supporting soil recovery processes. Reference [83] indicated that biomass-based coal derived from tobacco waste exhibits comparable performance to conventional coal under high-temperature curing with a higher combustion rate. Biomass coal showed improved energy efficiency from 39% to 42%, exceeding that of traditional coal combustion, which is around 36%. It is reported [12] that biomass-based coal from tobacco waste produces significantly lower emissions of CO₂, CO, and SO₂ compared to conventional coal, with the reduction numbers being 57.28%, 95.45%, and 98.06%, respectively. Hydrothermal carbonation of tobacco straw has also been shown to increase ignition temperature and energy density, enabling its conversion into high-energy solid fuel [18]. Moreover, the incorporation of trace graphene oxide during the hydrothermal carbonization of tobacco waste provides a high-energy hydrogen carbon material, indicating the feasibility methods of solid fuel production [84].

In addition to solid fuels, tobacco waste is suitable to produce activated carbon using KOH, K₂CO₃, and ZnCI₂, with the ZnCI₂-activated sample exhibiting favorable thermal stability [85]. Research in Italy approaches tobacco stems not as waste but as a potentially valuable renewable energy source, assessing their techno-economic and environmental potential in the domestic and urban sectors. These researchers also investigate the potential use of tobacco stalks after the drying process as a biomass fuel for boilers following a chipping treatment. Using burley tobacco stems collected from an air curing factory in Campania region of Italy, the study conducted a comparative energy, environmental, and economic analysis between a biomass and a natural gas boiler on a simulative basis. The results indicated that biomass boilers supplied with tobacco chips met thermal demands while providing environmental and economic advantages, including CO₂ emission reductions of up to 16.59t [86].

Several studies have focused on the utilization of tobacco waste to produce bio-oil and biogas. A study by [55] employed a fluidized bed reactor for tobacco stems pyrolysis, achieving a bio-oil yield of 67.47%, which surpassed yields from tobacco leaves and contained fewer harmful components compared to conventional tobacco smoke. The value of processing tobacco waste through pyrolysis is further confirmed [87] using ZnCl₂ and MgCl₂ as catalysts, producing fuel oil with favorable ignition properties. Moreover, tobacco residues are viable for biogas production, exhibiting an average methane potential of 248 Nm³ Mg⁻¹ [88].

Additionally, research in Thailand [23] studied the potential of tobacco waste for bioethanol production, and the findings demonstrate that integrated pretreatment and enzymatic hydrolysis can efficiently convert tobacco stalk waste into bioethanol, offering an environmentally friendly and economically viable approach for valorizing agricultural residues and supporting renewable energy production.

Overall, these studies underscore the significant potential of tobacco waste as a renewable energy source, capable of contributing to sustainable energy systems while mitigating environmental impacts associated with conventional fuels. On the other hand, taking into account that tobacco-derived feedstocks may carry residual heavy metals or alkaloids, it is important to consider potential contaminant transfer into the feed and food chain, underscoring the need for comprehensive life-cycle assessments (LCAs) and techno-economic analysis (TEA) assessments as well as long-term field-scale longevity and safety data.

6. Tobacco Waste Extracts as Medium for Cellulose Derivative Production

Tobacco waste, rich in sugars and polysaccharides, represents a promising renewable substrate for the production of esters of cellulose (acetate and nitrate) and bacterial cellulose (BC) [89], as presented in Table 3. The high sugar and polysaccharide content of tobacco stalks, along with the availability of fermentable components after detoxification, makes tobacco residues suitable for biotechnological processes targeting sustainable biomaterial production. Repurposing these residues for cellulose-based materials aligns with circular bioeconomy strategies, adding value to an underutilized agricultural by-product while reducing environmental impacts associated with waste disposal.

BC is a highly pure, crystalline, and mechanically strong form of cellulose synthesized by bacteria such as Gluconacetobacter, Acetobacter, Agrobacterium, and Rhizobium [90,91,92] using carbon-rich substrates such as glucose, sucrose, fructose, and glycerol in Hestrin–Schramm (HS) medium. Its unique properties enable applications in biomedicine, textiles, and acoustic devices [93,94,95], although high production costs limit broader industrial use [96]. It is demonstrated [89] that tobacco waste extracts could support BC synthesis, with optimal production (1.54 g/L) observed at a solid-to-liquid ratio of 1:10. Although nicotine inhibited BC production, steam distillation effectively removed nicotine, and BC yield increased by 47.4% after 90.9% nicotine removal, reaching 2.27 g/L. Optimizing fermentation conditions further enhanced BC synthesis. Adjusting pH to 6.5 and employing a two-stage fermentation strategy improved production to 5.2 g/L [97], and co-culturing Acetobacter oryzoeni MGC-N8819 with a nicotine-degrading strain, Pseudomonas sp. JY-Q/5Δ, further increased BC production to 6.0 g/L [98]. These studies highlight that tobacco waste is a feasible and sustainable substrate for BC production. Key factors influencing yields include sugar concentration, nicotine content, fermentation pH, oxygen availability, and co-culture strategies, demonstrating that a combination of chemical and biological optimizations can significantly enhance BC productivity and quality.

Cellulose nitrate is used in the production of inks, paints, adhesives, and explosives and is typically produced from cotton or wood pulp. Studies on potential production from tobacco stalks in Zimbabwe utilized both chemical and mechanical pulping techniques to synthesize various grades of nitrocellulose for a variety of applications with promising results [35]. The highly flammable cellulose nitrate can be replaced by cellulose acetate in the production of fibers and biodegradable plastics, and it can also serve as a carrier for the photosensitive layer in photography and cinematography [25].

Additionally, research in Turkey demonstrates that cellulose fibers extracted from Nicotiana stalks using a water retting method exhibited promising physical, chemical, and mechanical properties for an eco-friendly alternative to synthetic fibers, with lower lignin content [24].

Recent research also confirms that tobacco stalks are viable reinforcement materials for thermoplastic composites at 20–40 wt%. Increasing tobacco content generally improved mechanical properties, particularly tensile and flexural moduli, though performance varied by matrix and tobacco type. Burley tobacco stalks delivered the highest stiffness and lowest water absorption, making them ideal for structural applications, while Virginia and native tobacco offered moderate reinforcement but exhibited higher moisture uptake. Water absorption increased with fiber loading, emphasizing the need for moisture control in design. Overall, the study highlights the potential of tobacco stalks as sustainable, cost-effective reinforcements for composites, with matrix and fiber selection being critical to optimizing strength, dimensional stability, and durability [99].

Table 3. Cellulose-related materials produced from tobacco waste.

Output	Process	Conditions	Main Findings	References
Bacterial Cellulose (BC)	Fermentation using Acetobacter, Gluconacetobacter, Agrobacterium, and Rhizobium	Carbon-rich substrates from tobacco waste; pH ≈ 6.5; two-stage fermentation; co-culture; nicotine removal	BC production 1.54 g/L → 2.27 g/L after nicotine removal; optimized strategies increase yields to 5.2–6.0 g/L	[89,97,98]
Cellulose Nitrate (Nitrocellulose)	Mechanical and chemical pulping → nitration	Pulping conditions adjusted to produce specific grades	Suitable for inks, paints, adhesives, and explosives	[35]
Cellulose Acetate	Chemical acetylation of cellulose pulp	Used as a safer replacement for cellulose nitrate	Applications in fibers, biodegradable plastics, and photographic/cinematographic carriers	[25]
Cellulose Fibers from Nicotiana Stalks	Water retting	Lower lignin content; favorable physical and mechanical properties	Eco-friendly alternative to synthetic fibers	[24]
Thermoplastic Composites (20–40 wt% Stalks)	Reinforcement of polymer matrices with tobacco stalk fibers	Matrix selection; tobacco Burley best performance; moisture control needed	Higher tensile/flexural modulus; Burley = highest stiffness and lowest water uptake	[99]

Table 3. Cellulose-related materials produced from tobacco waste.

Output	Process	Conditions	Main Findings	References
Bacterial Cellulose (BC)	Fermentation using Acetobacter, Gluconacetobacter, Agrobacterium, and Rhizobium	Carbon-rich substrates from tobacco waste; pH ≈ 6.5; two-stage fermentation; co-culture; nicotine removal	BC production 1.54 g/L → 2.27 g/L after nicotine removal; optimized strategies increase yields to 5.2–6.0 g/L	[89,97,98]
Cellulose Nitrate (Nitrocellulose)	Mechanical and chemical pulping → nitration	Pulping conditions adjusted to produce specific grades	Suitable for inks, paints, adhesives, and explosives	[35]
Cellulose Acetate	Chemical acetylation of cellulose pulp	Used as a safer replacement for cellulose nitrate	Applications in fibers, biodegradable plastics, and photographic/cinematographic carriers	[25]
Cellulose Fibers from Nicotiana Stalks	Water retting	Lower lignin content; favorable physical and mechanical properties	Eco-friendly alternative to synthetic fibers	[24]
Thermoplastic Composites (20–40 wt% Stalks)	Reinforcement of polymer matrices with tobacco stalk fibers	Matrix selection; tobacco Burley best performance; moisture control needed	Higher tensile/flexural modulus; Burley = highest stiffness and lowest water uptake	[99]

7. Challenges and Conclusions

Tobacco stalks constitute a substantial yet underutilized agricultural residue with remarkable potential to support circular bioeconomy strategies. As demonstrated throughout this review, their high cellulose content, moderate lignin levels, and presence of bioactive compounds enable a wide range of applications, including renewable energy generation, soil quality improvement and contaminated land remediation, biopesticide development, and advanced biomaterial production such as cellulose derivatives and bacterial cellulose. These valorization pathways not only offer opportunities for resource recovery but also contribute to reducing environmental burdens associated with conventional disposal practices, which increase greenhouse gas emissions and soil degradation.

However, the potential of tobacco stalks must be assessed alongside their associated environmental risks. The presence of nicotine, a biologically active alkaloid, can inhibit soil microbial activity, suppress plant growth, and create ecotoxicological risks if not properly degraded prior to land application. Additionally, heavy metals and other contaminants present in tobacco tissues may be mobilized during thermochemical conversion or composting processes, creating risks of secondary pollution through contaminated ash, leachate, or emissions. Such concerns highlight the importance of carefully controlled pretreatment and safe end-use strategies to avoid shifting environmental burdens from one stage of the value chain to another.

Despite the promising applications of tobacco waste in energy production, several challenges hinder large-scale implementation. Efficient detoxification and pretreatment remain necessary to ensure environmental safety and regulatory compliance. Further complicating commercialization, the variability in chemical composition across tobacco varieties and cultivation practices affects process standardization and scalability. Economic feasibility also remains a major barrier, particularly for high-value products such as nanocellulose and bacterial cellulose, which require optimized, cost-efficient processing and integrated biorefinery approaches. Comprehensive LCA and TEA are essential to evaluate the sustainability, risks, and profitability of these valorization routes. Future research should focus on developing integrated solutions that bring together thermochemical and biological processes, supported by digital tools that help optimize operations and improve resource use. At the same time, supportive policies and strong collaboration between industry and regulators will be essential to encourage the adoption of circular economic practices within the tobacco sector. With the right innovations in place, tobacco waste can shift from being an environmental burden to a valuable resource that strengthens climate resilience, improving soil health and generating meaningful social and economic benefits in line with global sustainability objectives.