Hemp Stalks Research Articles

CONSIDERAŢII PRIVIND RECOLTAREA TULPINII DE CÂNEPĂ UTILIZÂND UN ECHIPAMENT SPECIALIZAT

Within the current hemp cultivation technologies, the use of high-performance technical equipment is required for all applied works, and following the concerns regarding diversified and efficient ways of harvesting, INMA Bucharest has created and experimented an innovative technical equipment for harvesting and tying the stalks into sheaves. In order to demonstrate the efficiency of this equipment, the paper presents the experimental results obtained by INMA Bucharest regarding hourly fuel consumption and fuel consumption per hectare. These energetic indices are important in the evaluation of expenses per surface unit, constituting the basis of the economic efficiency evaluation. At the same time, at ARDS Secuieni, in 2021, research was carried out on the influence of the cuttings application and different sowing norms on the agro-productive capacity of the Ratza monoecious hemp variety for stalks and fibre. The obtained results constitute premises in order to optimize some technological links of cultivation at hemp for stalks and fibre, but they also confirmed the fact that fuel consumption per hectare recorded at hemp stalks harvesting was influenced both by the technical characteristics of the equipment used and by the characteristics of the experimented crop.

Biochemical preparation of hydrophobic and lipophilic nanocellulose from hemp stalk

In this paper, an efficient, unmodified, and clean biological method was provided to prepare high crystallinity nanocellulose for the high-value green application of hemp stalk. The biological method of nanocellulose (NCs-B) was prepared with the enzyme and a small amount of alkali, while the chemical method of nanocellulose (NCs-C) was prepared with strong acid. By fitting small-angle X-ray diffraction with the quantitative polydispersity hypothesis, the cross-sectional morphology and capacity distribution were analyzed. The structure and performance of NCs were characterized by wide-angle diffraction, Fourier transform infrared spectrum, transmission electron microscope , contact angle, and Zeta potential. The distribution of the unit volume capacity of NCs-B was 13.9%, which was higher than that of NCs-C (5.9%) prepared by the conventional chemical method. The diameter and length of NCs-B were 1.77 nm and 171.6 nm, accounting for 54% and 143% of the NCs-C, respectively. The preparation rate of NCs-B was 40.64%, and the utilization rate of cellulose reached 83.14%, which was 1.39 times that of NCs-C. The crystallinity of NCs-B (63.31%) was similar to that of NCs-C, but was significantly higher than that of other methods. The NCs-B was hydrophobic (108.4°), which was different from the hydrophilicity of NCs-C (39.6°). The cell viability of NCs-B was 140%, which was 2.4 times that of NCs-C, and it was non-toxic.

Nutritional Values of Industrial Hemp Byproducts for Dairy Cattle.

The objective of this experiment was to explore the nutritional components of industrial hemp byproducts (industrial hemp ethanol extraction byproduct, IHEEB; industrial hemp stalk, IHS; industrial hemp seed meal, IHSM; industrial hemp oil filter residue, IHOFR) and provide theoretical support for the application of industrial hemp byproducts in dairy cattle production. This experiment used a combination of a wet chemical method with Cornell Net Carbohydrate and Protein System, in situ nylon bag technique, and three-step in vitro method to compare the chemical composition, carbohydrate and protein composition, in situ ruminal degradability and intestinal digestibility of industrial hemp byproducts and conventional feeds (alfalfa hay, AH; soybean meal, SBM). Available energy values were estimated based on the National Academies of Sciences, Engineering, and Medicine. The results showed that the nutritional composition of different feeds varied greatly. The two types of IHEEB were enriched with ash, crude protein (CP), neutral detergent fiber (NDF), and calcium, while the contents of neutral detergent insoluble crude protein, acid detergent insoluble crude protein, and acid detergent lignin were higher. As a result, the non-degradable carbohydrate and protein components were higher, and the effective degradation rate of rumen dry matter and protein was lower. IHS contains higher non-protein nitrogen and NDF, which enables it to provide more CP rumen effective degradation rate and carbohydrates, but the high acid detergent fiber also limits its application. IHSM possesses 296 g/kg CP and high rumen undegradable protein and intestinal digested protein, which can provide rumen bypass protein in dairy cows, making it a potentially good protein source. IHOFR had higher ether extract, rumen available protein degradation rate, and total tract digested protein, which can provide more energy and easily degradable protein for lactating cows. The available energy value of IHEEB and IHS was lower than AH, while SBM is between IHFOR and IHSM. In addition, the tetrahydrocannabinol of three industrial hemp byproducts that have not been assessed by the European Food Safety Authority (EFSA) was tested to evaluate their safety, and all of them were less than the limit set by ESFA. In conclusion, industrial hemp byproducts can be considered for inclusion in dietary formulations as unconventional feed sources for dairy cattle, but the purpose of use needs to be properly considered.

Structure of Waste Hemp Stalks and Their Sound Absorbing Properties.

To broaden the application fields of waste hemp stalks, the macromolecular, supramolecular, and morphological structures of waste hemp stalks were analyzed, and the relationship between these properties and the sound absorption properties of the hemp stalks was explored. Then, waste hemp stalk/polycaprolactone sound-absorbing composite materials were prepared by the hot pressing method. The influence of hemp stalk length and mass fraction, and the density and thickness of the composite materials on the sound absorption properties of composites prepared with the hot pressing temperature set to 140 °C, the pressure set to 8 MPa, and the pressing time set to 30 min was investigated. The results showed that, when the sound energy acts on the hemp stalk, the force between the chain segments, the unique hollow structure, and the large specific surface, act together to attenuate the sound energy and convert it into heat and mechanical energy in the process of propagation, to produce a good sound absorption effect. When the hemp stalk length and mass fraction were set to 6 mm and 50%, respectively, and the density and thickness of the material were set to 0.30 g/cm3 and 1.5 cm, respectively, the average sound absorption coefficient of the waste hemp stalk/polycaprolactone sound-absorbing composite material was 0.44, the noise reduction coefficient was 0.42, the maximum sound absorption coefficient was 1.00, and the sound-absorbing band was wide. The study provided an experimental and theoretical basis for the development of waste hemp stalk/polycaprolactone sound-absorbing composite materials, and provided a new idea for the recycling of the waste hemp stalk.

Fabrication of Sound Absorption Gypsum/Hempcrete Composite with Robust Antistatic Electricity by Taguchi Optimization Method

ABSTRACT Hempcrete is a sustainable bio-composite consisting of the woody component of hemp stalk, and lime blended with water. Hempcrete has been considered as an eco-friendly alternative to traditional construction building materials. This study has fabricated hempcrete composite consists of gypsum and hemp shives for sound absorption, and graphite was incorporated to improve the antistatic electricity. Three controlled factors: the length of hemp, the content of hemp, and graphite with four levels for each factor were chosen. Taguchi method based on orthogonal array L16 was employed to conduct the experiments. According to the results of Taguchi’s orthogonal array L16, analysis of variance (ANOVA) was used to evaluate the effects of various factors. The determination of optimal production parameters of gypsum/hempcrete composite was also investigated. According to the analysis, it has indicated that hemp content and graphite were the two most effective parameters on sound absorption, where hemp content exhibited a significant effect at 99% confidence level, and the confidence level of graphite is 95%. The antistatic electricity of gypsum/hempcrete composite is highly related to the incorporation of graphite with 99% confidence level.

Unravelling the role of hemp straw derived cellulose in CMC/PVA hydrogel for sustained release of fluoroquinolone antibiotic

Cellulose fibres derived from hemp stalks, a prevalent biowaste in Northern India, were effectively converted into carboxymethyl cellulose (HS-CMC). Novel environmentally benign hydrogels were synthesized from HS-CMC and polyvinyl alcohol (PVA) using citric acid, a green crosslinker employing freeze-drying method. The HS-CMC/PVA hydrogels were successfully used for sustained release of fluoroquinolone antibiotic, norfloxacin. The hydrogels were characterized using FTIR, XRD, FE-SEM, EDS and thermal stability and evaluated for their carbonyl content, swelling ratio, in-vitro drug release behaviour and bactericidal properties. Successful isolation of cellulose from hemp stalks and its conversion into hydrogel with the presence of ester and carbonyl linkages was confirmed by FTIR. Thermal stability was impaired when cellulose fibres were converted into HS-CMC via carboxymethylation, as the crystalline structure was utterly disrupted. For the hydrogel, the equilibrium swelling ratios at pH -1.2 and 7.4 were assessed as 378.4 % and 538.7 %, respectively, higher than reported CMC hydrogels. The norfloxacin (NFX) encapsulated hydrogels exhibited good bactericidal properties with zone of inhibition of 19.2 ± 0.3 mm against E. coli and 16.4 ± 0.4 mm against S. aureus. The in-vitro release of NFX at pH 1.2 was 91 %, higher than pH 7.4 at 82 % with strong adherence to Higuchi kinetics model signifying that the release of NFX is via dissolution and diffusion. The release kinetics at different pH revealed Fickian behaviour establishing the potential of HS-CMC hydrogel for sustained release of norfloxacin.

Lamination of Cast Hemp Paper with Bio-Based Plastics for Sustainable Packaging: Structure-Thermomechanical Properties Relationship and Biodegradation Studies

Composite laminate recycling and waste disposal routes remain a burden to existing systems, requiring special treatment and separation. The inclusion of a plastic layer is important for several key properties that are required for food safety, which in turn has made these products exceptionally hard to substitute in food packaging. Yet, the continued use of non-degradable commodity plastics is unsustainable. In this research, we compare the four most promising biodegradable and bio-based plastics that could replace non-degradable plastics in laminates. Polyhydroxyalkanoate (PHA), polylactic acid (PLA), polybutylene succinate (PBS), and polybutylene succinate adipate (PBSA) were applied as a direct melt coating on porous cast hemp papers, and the final composite was compressed under three different loads: 0.5 MT, 1.5 MT, and 3.0 MT. To promote sustainable agriculture waste management, we opted to use cast paper made from ground hemp stalks. The formation of the composite structure was examined with scanning electron microscopy (SEM), while surface wetting on the paper side of the laminate was performed to understand structural changes induced by polymer impregnation into the paper layer. Mechanical performance properties were investigated with tensile and peel tests, and suitability for an extended range of temperatures was examined with dynamical mechanical analysis. An increase in compression pressure yielded up to a two-fold improvement in elastic modulus and tensile strength, while thermomechanical analysis revealed that the polymer’s transition into a viscoelastic state significantly affected the laminate’s storage modulus values. Biodegradation was performed in a controlled compost at 58 °C, resulting in full degradation within 40 to 80 days, with PLA and PHA laminates showing 40 and 50 days, respectively. Produced bioplastic laminates have a tremendous potential to replace polyolefin laminates in packaging applications.

Enhanced valorization of hemp stalk via chemo-catalytic and hydrothermal conversions

The integration and cascade utilization of the entire lignocellulosic biomass components to obtain high value-added chemicals or fuels are of high interest. Herein, a strategy combined the chemo-catalytic and hydrothermal liquification processes was developed for the conversion of raw biomass into high value-added furanic compounds and fuels. Firstly, optimal 58% yield of furfural and 40% yield of 5-methylfurfural were co-produced from hemicellulose and cellulose components of hemp stalk powder (HSP) using formic acid and NaI as the catalysts. Then, the lignin-rich solid residue left after chemo-catalytic process, can be simply converted into bio-oil and hydrochar via hydrothermal liquefaction with a high energy recovery efficiency (88%). Elemental analysis of the bio-oils and hydrochars, as well as the adsorbing capacity of the hydrochars were also investigated and discussed. The pioneering study on simultaneously production of furfural and 5-methylfurfural, as well as the cascade valorization strategy using a green, simple and efficient way may unwrap a new direction for the entire biomass utilization.

The hemp stalk surface microrelief research for the hemp harversting working tools design

The article presents the results of fundamental scientific research on scanning the surface of the stem of technical hemp by atomic force microscopy using high-precision nanometer equipment. The features of the microstructure of bast fibers are revealed, the parameters of their roughness for use in agricultural machinery for the sub-branch of hemp farming are determined.

Application of sustainable biosorbents from hemp for remediation copper(II)-containing wastewater

Heavy-metal pollution in water is an ongoing concern throughout the world. The effective biosorption of these pollutants using sustainable hemp biomass offers an eco-friendly alternative to expensive, chemically synthesized ion exchange resin, while providing another revenue stream for hemp producers to efficiently utilize the entire crop. The biosorbents were characterized by chemical composition, FTIR, SEM, and XRD, and the results indicated that the biosorbents could be a good alternative. In addition, the biosorption of copper(II) on hemp biosorbents was investigated as the effects of initial pH of the solution, initial copper(II) concentration, dosage of hemp biosorbents in the solution, particle size of hemp biosorbents, contact time, and temperature. The biosorption of copper(II) ions was pseudo-second-order adsorption. The rate-limiting step of biosorption is intraparticle diffusion. The maximum adsorption capacity obtained from the Langmuir isotherm for copper(II) ions is 86.96 mg/g. In addition, the biosorption process is proven to be a spontaneous chemical exothermic process through adsorption isotherms and thermodynamics. This research demonstrates the feasibility of using hemp stalks as a sustainable renewable biosorbent for wastewater treatment based on lab-scale experiments.

Devising technologies for harvesting hemp with belt threshers

This paper reports the system of devised technologies for harvesting hemp with belt hemp threshers. It is proposed to form a roll of mowed hemp stems on a belt and tramp it to the field edge for further processing of stems. That makes it possible to significantly improve the efficiency of mechanized processes when harvesting and processing the entire biological harvest of hemp. Thus, the level of handling hemp production systems has been increased. At the same time, the management of the process of roll formation of hemp stems has been improved. The technology of hemp harvesting has been improved with the possibility of obtaining raw materials for long fiber and therapeutic preparations. Two-phase harvesting (for seeds and fiber) has been proposed to be implemented by using belt hemp threshers included in the stationary (semi-stationary) complexes. The possibility of preparing the combed hemp retted stalks by spreading them on materials of various types has been systematically substantiated. The influence of the thickness of a layer of hemp stalks spread out for the preparation of retted stalks on the timing of their preparation and fiber quality indicators has been investigated. It was established that in terms of the quality indicators of the produced fiber, the retted stalks from all experiments are properly aged while the efficiency of their processing for medium- and large-stalk fraction is high. The fibers produced in all experiments were characterized by purity, as well as high indicators of breaking load and handful length. As regards the linear density, the fibers’ values in all experimental variants exceeded the normative ones by 1.65‒2.64 times, which rendered them non-standard. An increase in the values of quality indicators has been established with the corresponding change, from 1 to 3 kilograms per meter, in the thickness of the layer of combed hemp stalks. The breaking load, under such conditions, increased by 16.6 %; the linear density, by 20 %; the content of shives, by 60 %; the «paw» content, by 12.5 %, the content of bast strands, by 10.8 %.

Delignification of hemp stalk using a low transition temperature mixture composed of choline chloride and lactic acid

This work used a literature search to select the most suitable system for the delignification process of annual plants. This process was evaluated in terms of lignin removal from plant biomass. Based on previous experiments, a low transition temperature mixture (LTTM) was used, which was a mixture of choline chloride and lactic acid in a molar ratio of 1:2. Samples of hemp fibers were examined. The delignification of biomass was monitored by changing the content of the main components. After application of the solvent at a temperature of 100, 120, or 140 °C and a delignification time of 2 or 4 h, the lignin content expressed by Kappa number decreased to the level of 22 to 13.7. Yields of hemp fibers sown after LTTM application ranged from 72.5 to 90.6%. The results confirmed that the use of LTTM (choline chloride/lactic acid) is a suitable system for the extraction of lignin from biomass. The findings showed that LTTM was an effective delignifying agent for hemp, as a relatively low Kappa number of 13.7 and a yield of 75.9% were achieved after only 2 h and at 140 °C.

Application of Colloidal Chemistry and Polymer Chemistry in Papermaking Industry

Colloidal chemistry is a science to study the physicochemical properties of generalized colloidal dispersion systems. Polymer chemistry is a new comprehensive subject that studies the synthesis, chemical reaction, physical chemistry, physics, processing and application of polymer compounds. The development of polymer chemistry mainly experienced four periods: the utilization and processing of natural polymers, the modification of natural polymers, the production of synthetic polymers and the establishment of polymer science. Since the 1930s, with the development of synthetic polymers, polymer related sub disciplines such as reaction kinetics, chemical thermodynamics, structural chemistry, polymer physics and biopolymers have been gradually established, forming a systematic polymer science. Papermaking industry is an industrial sector that manufactures all kinds of paper and paperboard. It includes the pulp manufacturing industry that uses wood, reed, bagasse, straw, wheat straw, cotton straw, hemp stalk, cotton and other raw materials to manufacture pulp, the paper and paperboard industry, and the processing paper manufacturing industry that produces coated, polished, glued, laminated and other processing paper and font paper plate. Paper industry is an important industry closely related to the development of national economy and the construction of social civilization. This paper focuses on the relationship between colloidal chemistry, polymer chemistry and papermaking industry, especially its application in cooking, washing, bleaching, papermaking and water treatment, and introduces in detail the current situation and development trend of flocculation method for papermaking wastewater according to colloidal chemistry theory.

Study of an insulating hemp-based bio-material: mechanical, thermal and acoustic properties

Currently there is a need to develop more sustainable and renewable materials compromised with the environment. From these needs, hemp stalk has great potential because it is mostly a waste material. Moreover, hemp shives are a lightweight material with a high insulating property. This study aims to increase the knowledge in a material made solely from stalk and ECF (elementary chlorine free) bleached eucalyptus kraft pulp and a second 100% recycled material where the kraft pulp is replaced by recycled cardboard fiber, also a vegetable coating is added to protect against moisture. The hemp/fiber ratio influence is studied. Samples are evaluated in terms of mechanical behaviour (compression and shear), thermal and acoustic insulation. To study the thermal insulation, a testing camera is used where the heat transfer through the material is measured in order to study the thermal resistance. A Kundt tube is used in the acoustic insulation study to calculate the absorption of sound waves in a range from 0 to 6500 Hz. The results show that by increasing the percentage of hemp, the mechanical properties increase (compression and shear). Also, the eucalyptus pulp acts as a binder between the shives; nevertheless, if there is not enough, the material is not stable. Therefore, a maximum of 70 wt.% of hemp is recommended. In the case of thermal insulation, better thermal resistance is obtained in the case of 60 wt.% of hemp, while in acoustic insulation a higher percentage of hemp have a high performance, reaching attenuation values greater than 0.8 for frequencies greater than 1000Hz. The carboard sample improves the shear and acoustic insulation performance. The coating improves the thermal resistance but worsens the acoustic insulation.

Enhanced Valorization of Hemp Stalk Via Chemo-Catalytic and Hydrothermal Conversions

Enhanced Valorization of Hemp Stalk Via Chemo-Catalytic and Hydrothermal Conversions

Revealing the Roles of Biomass Components in the Biosorption of Heavy Metals in Wastewater by Various Chemically Treated Hemp Stalks

Revealing the Roles of Biomass Components in the Biosorption of Heavy Metals in Wastewater by Various Chemically Treated Hemp Stalks

Holistic Valorization of Hemp through Reductive Catalytic Fractionation.

Despite the increased use of hemp fiber, negligible attention has been given to upgrade the hemp hurd, which constitutes up to 70 wt % of the hemp stalk and is currently considered a low-value byproduct. In this work, valorization of hemp hurd was performed by reductive catalytic fractionation (RCF) in the presence of a metal catalyst. We found an unexpectedly high yield of monophenolic compounds (38.3 wt %) corresponding to above 95% of the theoretical maximum yield. The high yield is explained by both a thin cell wall and high S-lignin content. In addition, organosolv pulping was performed to generate a pulp that was bleached to produce dissolving-grade pulp suitable for textile fiber production (viscosity, 898 mL/g; ISO-brightness, 90.2%) and nanocellulose. Thus, we have demonstrated a novel value chain from a low-value side stream of hemp fiber manufacture that has the potential to increase textile fiber production with 100% yield and also give bio-oil for green chemicals.

Economic viability of industrial hemp production in Turkey

Recent developments in industrial hemp sector have resulted in several differentiations in production, marketing, logistic and consumption pattern of industrial hemp (Cannabis sativa L.). Therefore, the study examined the economic viability of industrial hemp production in Turkey. Research data were collected from industrial hemp producers by using structured questionnaire and from Ministry of Agriculture and Forestry and other stakeholders such as merchants, retailer, and e-marketing platform through semi structured interview. Efficiency measures generated by data envelopment analysis (DEA), strengths, weaknesses, opportunities, and threats (SWOT) analysis and profitability measures were used to explore economic viability of industrial hemp production. Research findings showed that hemp stalk production cost per kilogram of only hemp fiber growing and dual-purpose growing were US $0.29/kg and US $0.41/kg, respectively. Dual-purpose growing model had the highest net revenue per hectare. Industrial hemp had the competitive advantage over fiber flax (Linum usitatissimum L.), while reverse was the case for cotton fiber and seed production (Gossypium sp.). Based on the findings of efficiency analysis, the mean economic, allocative, and technical efficiencies were 0.77, 0.92, and 0.84, respectively. Productive efficiency level of dual-purpose growing was higher comparing with other growing models. Research findings also showed that farm level hemp production and processing hemp by modern technology was economically viable, while the viability of processing hemp by conventional technology was not profitable in Turkey. The results of SWOT analysis revealed that lacking data, problems related mechanism of hemp markets, hemp value chain, production, lacking research and development (R&D), and legislation problems were main issues in Turkey. The study suggests encouraging the R&D activities and investments in hemp breeding and genetics, and developing processing facility of hemp farms to produce fiber and seed-based product. Producing hemp with appropriate cropping system and increasing technical knowledge of hemp farmers, especially on sex determination may positively affect the economic viability of hemp production.

Valorization of Hemp Stalk Waste Through Thermochemical Conversion for Energy and Electrical Applications

The presented research aimed at finding new ways to value hemp by-products (stalks) from the cannabidiol industry through thermochemical conversion. Chemical and elemental composition of hemp biomass was investigated by successive chemical extractions and Scanning Electron Microscopy along with Energy-dispersive X-ray Spectroscopy. Proximate and elemental analyses completed the chemical characterization of the hemp biomass and its biochar. Thermogravimetric analysis of the hemp biomass allowed to understand its kinetic of decomposition during thermal conversion. The carbon structure and porosity of the biochar were assessed by Raman spectroscopy and CO2 gas adsorption. Properties of interest were the energy production measured through calorific values, and the electrical conductivity. Two ways of valorisation of the hemp biomass were clearly identified, depending mainly on the chosen pyrolysis temperature. Hemp biochar carbonized at 400–600°C were classified as lignocellulosic materials with a good potential for solid biofuel applications. Specifically, the resulting carbonized biochar presented low moisture content (below 2.50%) favourable for high fuel quality, low volatile matter (27.1–10.4%) likely to show lower particle matter emissions, limited ash content (6.8–9.8%) resulting in low risk of fouling issues during the combustion, high carbon content (73.8–86.8%) suggesting strong energy density, associated with high higher heating values (28.45–30.95 MJ kg−1). Hemp biochar carbonized at 800–1000 °C displayed interesting electrical conductivity, opening opportunities for its use in electrical purposes. The electrical conductivity was related to the evolution of the biochar microstructure (development of graphite-like structure and changes in microporosity) in regard with the thermochemical conversion process parameters.Graphical abstract

Valorization of Hemp Stalk Waste Through Thermochemical Conversion for Energy and Electrical Applications

Valorization of Hemp Stalk Waste Through Thermochemical Conversion for Energy and Electrical Applications