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Lignocellulosic biomass, including that of energy crops, can be an alternative source to produce activated carbons (ACs). Miscanthus and switchgrass straw were used to produce ACs in a two-step process. Crushed plant material was carbonized at 600 °C and then obtained carbon was activated using NaOH or KOH at 750 °C. The content of surface oxygen groups was determined using Boehm’s method. The porosity of ACs was assayed using the nitrogen adsorption/desorption technique, while their thermal resistance using the thermogravimetric method. The ACs derived from miscanthus and switchgrass were characterized by surfaces rich in chemical groups and a highly developed porous structure. The highest specific surface areas, over 1600 m2/g, were obtained after carbon treatment with NaOH. High values of iodine number, 1200–1240 mg/g, indicate an extensive system of micropores and their good adsorption properties. The type of activator affected the contents of oxygen functional groups and some porosity parameters as well as thermal stability ranges of the ACs. Among obtained carbons, the highest quality was found for these derived from M. sacchariflorus followed by switchgrass, after activation with NaOH. Hence, while these crop species are not as effective biomass sources as other energy grasses, they can become valuable feedstocks for ACs.

Nanocellulose has gained increasing attention during the past decade, which is related to its unique properties and wide application. In this paper, nanocellulose samples were produced via hydrolysis with ionic liquids (1-ethyl-3-methylimidazole acetate (EmimOAc) and 1-allyl-3-methylimidazolium chloride (AmimCl)) from microcrystalline celluloses (Avicel and Whatman) subjected to enzymatic pretreatment. The obtained material was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). The results showed that the nanocellulose had a regular and spherical structure with diameters of 30–40 nm and exhibited lower crystallinity and thermal stability than the material obtained after hydrolysis with Trichoderma reesei enzymes. However, the enzyme-pretreated Avicel had a particle size of about 200 nm and a cellulose II structure. A two-step process involving enzyme pretreatment and hydrolysis with ionic liquids resulted in the production of nanocellulose. Moreover, the particle size of nanocellulose and its structure depend on the ionic liquid used.

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Adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-metylphenoxyacetic acid (MCPA) from aqueous solution onto activated carbons derived from various lignocellulosic materials including willow, miscanthus, flax, and hemp shives was investigated. The adsorption kinetic data were analyzed using two kinetic models: the pseudo-first order and pseudo-second order equations. The adsorption kinetics of both herbicides was better represented by the pseudo-second order model. The adsorption isotherms of 2,4-D and MCPA on the activated carbons were analyzed using the Freundlich and Langmuir isotherm models. The equilibrium data followed the Langmuir isotherm. The effect of pH on the adsorption was also studied. The results showed that the activated carbons prepared from the lignocellulosic materials are efficient adsorbents for the removal of 2,4-D and MCPA from aqueous solutions.

Modification of lignocellulose materials, used as fillers in the composites with polyolefins, is applied to improve their adhesion to the matrix. One of the most often applied methods of such modification is the treatment with organic acid anhydrides. Rapeseed straw was modified with anhydrides of acetic, maleic and succinic acids. Such a modification changes the straw surface leading to the exposition of the wood tissue skeleton. The character changes depending on the type of anhydride applied. Esterification of repeseed straw by organic acid anhydrides resulted in changes in its chemical structure. According to infrared analysis of modified straw, new carbonyl groups were formed, as indicated by the absorption band in the range 1750–1730 cm−1. The degree of straw modification, measured by the weight percent gain index, informs about similar reactivities of the lignocelluloses material with all three anhydrides of organic acids used as modifiers. The starting temperatures of active thermolysis for the straw modified with maleic and succinic acid anhydrides were lower than that for native straw, while that for the straw modified with acetic acid was higher. Concentration of free radicals in rapeseed straw samples was measured by electron paramagnetic resonance spectroscopy. It was found that the maximum concentration of radicals for rapeseed straw was treated with maleic anhydride.

The paper investigates the effect of surface modification of fumed nanosilica with (3-aminopropyl) triethoxysilane (APTES) on the kinetics and thermal stability of urea-formaldehyde (UF) resin. In the course of the investigation, nanoparticles were modified with APTES in the ratio 1, 2, 3, 4 and 5 part by weight (PBW) per 100 PBW of SiO 2 . The parameters of curing kinetics of the resin, the conversion degree and its thermal stability were determined with use of differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The effect of nanosilica silanization on the curing process of resin was evaluated by determining the gel time at 100°C and the activation energy (E a ) of the crosslinking process, the initial and final temperature of the reaction (T onset , T endset ), the maximum value of the exothermic peak (T p ), the amount of emitted heat (ΔH Tp ) and the conversion degree (α Tp ) that responds to T p . With the maximum level of silica modification, we have noted a decrease in the reactivity of the resin, which is manifested by a slightly longer gel time of the resin as well as an increase in the value of activation energy of the cross-linking process. It is accompanied by a slight decrease of resin conversion degree α Tp . The modification of silica, regardless of the amount of silane inoculated on its surface, results in the increase in the thermal stability of UF resin.

Activated carbons have been obtained from the following organic precursors (lignocellulosic waste materials): willow, rapeseed straw, hemp shives, flax shives, switch grass, Virginia mallow and giant miscanthus. The activation process has been performed by using potassium hydroxide at 750 °C. Elemental analysis has been performed in order to determine the presence of heteroatoms in the carbon structure. Boehm titration was used to estimate the functional groups of carbon materials. The surface area was characterized using gas adsorption method. All the obtained samples have been used as electrodes for electrochemical capacitors operated in 1 M H 2 SO 4. The electrochemical characterization was carried out using cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. All measurements proved that carbon materials obtained from different lignocellulosic wastes are suitable for energy storage applications. Moreover, the content of oxygen groups has great influence on the charge storage mechanism. Excessive oxygen content causes the disruption of surface conjugation of the carbon material.