1,721,007 research outputs found
Gelatin Beads/Hemp Hurd as pH Sensitive Devices for Delivery of Eugenol as Green Pesticide
No full textIn this paper gelatin beads reinforced with natural hemp hurd have been produced as pH sensitive devices for the release of eugenol, as green pesticide. The composites beads, with a mean diameter of about 1 mm, were obtained by polymer droplet gelation in sunflower oil. Thermal properties were evaluated showing no noticeable difference after the introduction of hemp hurd. Barrier properties demonstrated an improvement of hydrophobization. The introduction of 5% w/w of hemp hurd led to a reduction of sorption coefficient of about 85% compared to unloaded gelatin beads. Besides, the diffusion coefficient decreased, introducing 5% w/w of hemp hurd, from 8.91 × 10−7 to 0.77 × 10−7 cm2/s. Swelling and dissolution phenomena of gelatin beads were studied as function of pH. The swelling of gelatin beads raised as pH increased up to 2.3 g/g, 9.1 g/g and 27.33 g/g at pH 3, 7 and 12, respectively. The dissolution rate changed from 0.034 at pH 3 to 0.077 h−1 at pH 12. Release kinetics of eugenol at different pH conditions were studied. The released eugenol after 24 h is 98%, 91%, 81 and 63% w/w (pH 3), 87%, 62%, 37 and 32 wt% (pH 7) and 81%, 68%, 60 and 52 wt% (pH 12) for unloaded gelatin beads and gelatin beads with 1%, 3 and 5% of hemp hurd, respectively. The eugenol release behavior was demonstrated to be highly sensitive to the pH release medium, which allows to tune such devices as green pesticide release systems in soils with different level of acidity/basicity
A novel approach to design sustainable fiber reinforced materials from renewable sources: Mathematical modeling for the evaluation of the effect of fiber content on biocomposite properties
No full textThe paper reports a sustainable, fast and efficient methodology to treat natural hemp fibers (HF) using a mechanochemical approach. Mechanical milling was used to carry out an alkaline attack on HFs for 30 min at ambient temperature. Composites HF/pectins were prepared by varying the fiber weight fraction (3%; 7.5%; 10%; 20% w/w by weight). The improvement in thermal degradation, mechanical and barrier properties to water vapor was correlated with the fiber volume fraction and mainly due to the improved fiber-matrix adhesion. The fibers-matrix interaction was then evaluated by analyzing and modeling the mechanical properties using several mathematical models: a modified Nielsen and Pukànszky and Smith models. Sorption isotherms to water vapor were analyzed through a modified Guggenheim, Anderson, de Boer (GAB) model where a new parameter, α, was introduced to consider the heterogeneity of the system. Finally, a modified Burgemman model was used to fit the experimental data and support the improvement in water diffusion with fiber loading
Organizational assimilation capacity and IT Business Value
No full textOrganizational assimilation capacity and IT Business Valu
Facile preparation of layered double hydroxide (LDH)-alginate beads as sustainable system for the triggered release of diclofenac: Effect of pH and temperature on release rate
No full textThis paper concerns the facile preparation of alginate beads encapsulating layered double hydroxide (LDH) intercalated with diclofenac sodium as drug delivery systems. To better evaluate the effect of LDH carrier, alginate beads loaded with free diclofenac were also prepared. Composites hydrogel beads were ionotropically crosslinked in CaCl2 solution at 4 °C. Thermal and barrier properties were evaluated and correlated with the presence of the inorganic phase. Swelling behavior was investigated over time. Release kinetics of diclofenac at different pH and temperatures were evaluated. The diclofenac release behavior appeared to be affected by the presence of LDH, the pH of release medium and the temperature allowing for fabricating a sustainable composite characterized by a triggered drug release rate. Finally, empirical relationships correlating the drug diffusion as a function of temperature and pH were extrapolated
Fabrication and characterization of electrospun membranes based on “poly(ε-caprolactone)”, “poly(3-hydroxybutyrate)” and their blend for tunable drug delivery of curcumin
No full textMembranes based on poly(ε-caprolactone)/poly(3-hydroxybutyrate) blends (PCL/PHB at 50 wt%) were obtained by electrospinning and curcumin encapsulated at 1 wt% as active agent, as drug delivery systems for biomedical applications. PCL and PHB were also separately electrospinned and loaded with 1 wt% of curcumin. The processing parameters of PHB were drastically different from PCL and the blend PCL/PHB; in fact, the temperature used was 40◦ C, and the distance injector–collector was 28 cm. Different conditions were used for PCL: lower temperature (i.e., 25◦ C) and shorter distance injector–collector (i.e., 18 cm). The blend was processed in the same conditions of PCL. The fibers obtained with PHB showed diameters in the order of magnitude of micron (i.e., ≈ 3.45 μm), while the PCL mats is composed of fiber of nanometric dimensions (i.e., ≈ 340 nm). PCL/PHB blend allowed to obtain nanometric fibers (i.e., ≈520 nm). Same trend of results was obtained for the fibers’ porosity. The morphology, thermal, mechanical and barrier properties (sorption and diffusion) through water vapor were evaluated on all the electrospun fibers, as well as the release behavior of curcumin, and correlated to the processing parameter and the fibers’ morphologies
Design of sodium alginate/soybean extract beads loaded with hemp hurd and halloysite as novel and sustainable systems for methylene blue adsorption
No full textThis work concerns the fabrication of a green, novel, and sustainable system for the efficient removal of methylene blue from aqueous solutions. The proposed system is obtained by using sodium alginate/soybean extract blend reinforced with hemp hurd from agro-waste resources and halloysite nanotubes (HNTs). The ionotropic gelation methodology, using calcium chloride as a crosslinking agent, was easily applied to obtain composite beads. The adsorption studies were carried out up to 24 h using methylene blue as model system. The effect of HNTs on adsorption capacity was investigated proving that an increase in inorganic filler determined an increase in adsorption capacity from 32 to 49 mg/g by adding 35% wt of HNTs. The experimental data were fitted through four different models, demonstrating that the adsorption phenomenon is described by second-order process. Film diffusion and pore diffusion values were evaluated to better investigate the rate controlling mechanisms. Isotherm studies were then carried out to extrapolate thermodynamic parameters. Finally, a possible mechanism of adsorption was proposed on the basis of chemisorption mechanism. Here, we demonstrate that the proposed novel, inexpensive, and sustainable composite material obtained from agro-waste resources has high efficiency in removing a cationic dye from wastewaters
Fabrication of rice flour films reinforced with hemp hurd and loaded with grapefruit seed oil: A simple way to valorize agro-waste resources toward low cost materials with added value
No full textNovel biodegradable films based on rice flour loaded with hemp hurd powder and grapefruit seed oil, as a mixture of natural compounds with potential antimicrobial activity, were fabricated and morphologically analyzed. Mechanical and thermal analysis were correlated to the hemp hurd content showing that no increase in thermal stability occurred for the rice flour composite while a noticeable improvement in mechanical properties was achieved after the addition of hemp hurd (up to 300 % of the pure rice flour film for a reinforcement loading of 20 % wt). Barrier properties were then studied aiming of evaluating the effect of hemp hurd on water sorption and diffusion. The decrease in polar site of rice flour and the hydrophobic character of either hemp hurd or essential oil led to a reduction of either the sorption parameter (about 85 % with a hemp hurd amount of 20 %wt) or the diffusion one (up to 96 % with a hemp hurd amount of 20 %wt). Optical properties appeared to not be pretty sensitive to hemp hurd presence. The release of a grapefruit seed oil was then studied through a second-order model and correlated with the effect of hemp hurd loading
Modification of hemp fibers through alkaline attack assisted by mechanical milling: effect of processing time on the morphology of the system
No full textThis paper reports the possibility of functionalizing hemp fibers (HF) through a mechano-chemical treatment assisted by an easily scalable top-down technology. The mechanical action was able to remove non-cellulosic material and to cause exposure of the cellulose microfibrils. Its influence on structure, morphology, and properties of hemp fibers has been analyzed by means of the scanning electron microscopy, X-Ray, FTIR and Raman spectroscopy. The milling process induced a change in crystalline content of hemp fibers, which decreased after a treatment time of 30 min. The crystallinity index and cellulose chain arrangement influence the thermal stability of hemp fibers. In order to compare the improved properties of mechanochemically treated HF respect to the HF modified with conventional alkalization, they were introduced, as green reinforcement, into a pectin matrix. Thermal and mechanical properties demonstrated the effectiveness of milling treatment in improving the considered physical properties of the pectin matrix
Design of a hybrid bio-adsorbent based on Sodium Alginate/Halloysite/Hemp hurd for methylene blue dye removal: kinetic studies and mathematical modeling
No full textThis research aims for designing and fabricating green and sustainable systems for an efficient removal of methylene blue from aqueous solutions. The hybrid beads, obtained by using ionotropic gelation technique and calcium chloride as cross-linking agent, are composed of sodium alginate matrix, hemp hurd as agro-waste resource and halloysite nanoclay (HNTs). The produced composite beads were characterized morphologically by using SEM and EDX techniques. The batch adsorption studies were performed up to 24 h using methylene blue (MB) as model hazardous dye in order to investigate the effect of HNTs content (0–35% wt) and pH (2, 7 and 12) on the adsorption capacity. In neutral conditions, a maximum adsorption capacity of 32 mg/g was obtained for sample with 0% of HNTs while it increases up to 41, 43 and 50 mg/g for 5%, 20% and 35%wt, respectively. Moreover, swelling/deswelling behavior and point of zero charge (PZC) analysis were even investigated since they are known to affect the adsorption process. A slight increase in PZC can be observed by adding clay nanotubes from 7.42 (0% wt HNTs) up to 7.98 (35% wt HNTs). The experimental data were fitted through first order model, pseudo-second order model and intraparticle diffusion model, demonstrating that the adsorption phenomenon is well described by second order process as well as that the process is mainly characterized by boundary diffusion and intraparticle diffusion. Finally, diffusion of dye was evaluated as function of HNTs content and H+ concentration appearing to decrease from pH= 2 up to pH= 7 and then to increase in alkaline medium (pH=12). Diffusion coefficient and recovery % trends were modeled through design of experiment methodology
Hemp fibers modified with graphite oxide as green and efficient solution for water remediation: Application to methylene blue
No full textIn this paper, the use of hemp fibers modified with graphite oxide for the removal of methylene blue (MB) from aqueous solutions was investigated. Parameters such as contact time, pH, temperature, initial concentration of dye and ionic strength were varied and their effects on the adsorption recovery were evaluated. The adsorption process attained the equilibrium within 30 min while the adsorption capacity was found to increase with increasing contact time. The experimental data were fitted through a pseudo-second order model. Maximum adsorption capacity slightly increases with temperature changing from 54 mg/g to 58 mg/g at pH = 7.5, from 37 mg/g to 45 mg/g at pH = 3 and from 44 mg/g to 49 mg/g at pH = 12, by increasing the temperature from 20 °C to 80 °C indicating that the process is slightly endothermic (ΔH = 3.43 kJ/mol). The thermodynamic parameters were even calculated demonstrating that the process is spontaneous (ΔG ≈ −4.4 J/mol K and ΔS = 3.16 J/mol K)). Finally, a mathematical algorithm was applied to forecast the response surface model. A second order model was chosen to fit the experimental data and the statistical effect of the process parameters were estimated. A numerical optimization was even performed to individuate the optimal set of process parameters (pH = 9.25, T = 53.8 °C and C0 = 13.2 mg/L) which maximizes the removal capacity. A possible adsorption mechanism was even presented. So, it was proved the efficiency of the adsorption of a novel, inexpensive and sustainable composite material obtained from agro-waste resources by performing reusability cycles
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