A multilevel factorial design of 2
with 12 experiments was developed for the preparation of cellulose nanocrystals (CNC) from
Weber var. Azul bagasse, an agro-industrial waste from tequila ...production. The studied parameters were acid type (H
SO
and HCl), acid concentration (60 and 65 wt% for H
SO
, 2 and 8N for HCl) temperature (40 and 60 °C for H
SO
, 50 and 90 °C for HCl), and hydrolysis time (40, 55 and 70 min for H
SO
; and 30, 115 and 200 min for HCl). The obtained CNC were physical and chemically characterized using dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XDR) techniques. The maximum CNC yield was 90 and 96% for HCL and H
SO
, respectively, and the crystallinity values ranged from 88-91%. The size and morphology of
CNC strongly depends on the acid type and hydrolysis time. The shortest CNC obtained with H
SO
(65 wt%, 40 °C, and 70 min) had a length of 137 ± 68 nm, width 33 ± 7 nm, and height 9.1 nm, whereas the shortest CNC obtained with HCl (2 N, 50 °C and 30 min) had a length of 216 ± 73 nm, width 69 ± 17 nm, and height 8.9 nm. In general, the obtained CNC had an ellipsoidal shape, whereas CNC prepared from H
SO
were shorter and thinner than those obtained with HCl. The total sulfate group content of CNC obtained with H
SO
increased with time, temperature, and acid concentration, exhibiting an exponential behavior of CSG=aebt.
Natural lignocellulosic biomass is a valuable feedstock for soluble-grade cellulose (α-cellulose > 90%) with advantageous features such as abundance, high strength, rigid structure, low weight, and ...it is biodegradable. The bagasse from Agave tequilana Weber var. azul is the main agroindustrial waste from the tequila industry and poses an environmental threat. However, due to its high cellulose content, Agave tequilana bagasse is an excellent candidate for the extraction and utilization of its components. In this study, alkaline cooking, followed by five stages of bleaching, was employed to obtain soluble-grade cellulose pulp. The obtained soda pulp material had a Kappa number (KN) of 23 ± 3, viscosity (μ) of 11.53 to 10.18 cp, degree of polymerization (DP) of 830 to 750, brightness of 87.5%, and percentage of alpha-cellulose (α) of 81 ± 3 at 94 ± 3%. The obtained material was characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy to compare its properties with published information. The waste of A. tequilana Weber var. azul produced pulp with a high percentage of alpha cellulose and a high crystallinity degree. This methodology is novel and simple for the production of soluble-grade cellulose pulp, a raw material for the production of cellulose nanocrystals.
Considering that many paper mills have modified their pulp manufacturing processes to produce dissolving grade pulps from a wide variety of woods, which can be used for the production of different ...end products, attempts have also been made to obtain highly purified pulps using several woods and non-timber as raw materials using chemical routes. This paper is an attempt to overcome the problem of the shortage of commercial timber for pulping purposes wherein non-commercial, widely distributed huizache, a woody plant, was evaluated as a raw material for the production of dissolving grade cellulose using an alkaline sulfur anthraquinone-methanol process with a pre-hydrolysis step and optimized conditions of the process. The pulp obtained from the cooking process was subjected to a sequence of elemental chlorine free bleaching. The pulp was analyzed for its performance during the pulping process, Kappa number, ISO brightness, contents of α, β, and γ cellulose, crystallinity index, degree of polymerization, and viscosity. The obtained results revealed high levels of all these parameters for the pulp produced from Acacia farnesiana, suggesting this plant could be considered as a raw material alternative for the production of dissolving grade cellulose, which in turn can be used to produce nanocellulose crystals.
High purity cellulose nanocrystals (NCCs) were obtained through the generation of various nanoparticle suspensions from different hydrolysis conditions of soluble grade cellulose (α-cellulose) ...prepared from huizache wood (Acacia farnesiana L. Willd.). These NCCs exhibited different surface morphologies and properties. Hydrolysis was carried out using both sulfuric and hydrochloric acids, while the methodology was based on 23 factorial designs of experiments. The obtained nanocrystals were characterized for particle size distribution, morphology, size of the NCCs, residual surface charge of the nanoparticles, and chemical composition using various experimental techniques. The two acid hydrolysis procedures produced NCCs suspensions that exhibited a unimodal or bimodal pattern of the Gaussian type, but differed in their properties. Average NCCs particle size obtained by hydrolysis with different concentrations (60 to 65%), at different temperatures (45 to 55 oC) and treatment times (45 to 65 mins) with H2SO4 acid and HCl acid were approximately 100 to 260 nm and between 75 nm to 512 nm, respectively, indicating influence of concentration and treatment time with both acids. Also, residual load analysis of sulphate groups in the NCCs suspensions in producing NCCs by H2SO4 hydrolysis revealed a minimum load of 39 mmol/kg and a maximum of 505 mmol/kg of NCCs.
The dehydrogenation temperature of LiAlH4 was significantly reduced by the production of mixtures with ZrCl4. Stoichiometric 4:1, and 5 mol % mixtures of LiAlH4 and ZrCl4 were produced by ball ...milling at room temperature and −196 °C, and tested for dehydrogenation at low temperature. Cryogenic ball-milling resulted in an effective way to produce reactive mixtures for hydrogen release; because of achieving small aggregates size (5–20 μm) in 10 min of cryomilling while preventing substantial decomposition during preparation. Dehydrogenation reaction in the mixtures LiAlH4/ZrCl4 started around 31–47 °C under different heating rates. Partial dehydrogenation was proved at 70 °C: 4.4 wt % for the 5 mol% ZrCl4–LiAlH4 mixture, and 3.4 wt % for the best 4:1 stoichiometric mixture. Complete dehydrogenation up to 250 °C released 6.4 wt% and 4.1 wt%, respectively. Dehydrogenation reactions are exothermic, and the LiAlH4/ZrCl4 mixtures are unstable and difficult to handle. The activation energy of the exothermic reactions was estimated as 113.5 ± 9.8 kJ/mol and 40.6 ± 6.6 kJ/mol for 4LiAlH4+ZrCl4 and 5%mol ZrCl4+LiAlH4 samples milled in cryogenic conditions, respectively. The dehydrogenation pathway was changed in the LiAlH4/ZrCl4 mixtures as compared to pure LiAlH4. Dehydrogenation reaction is proposed to form Al, LiCl, Zr, and H2 as main products. Modification of the dehydrogenation reaction of LiAlH4 was achieved at the cost of reducing the total hydrogen release capacity.
Programmed desorption temperature of LiAlH4/ZrCl4 mixtures and LiAlH4. Display omitted
•Use of cryogenic ball-milling for producing low-temperature hydrogen release materials.•Formation of reactive mixtures 4LiAlH4+ZrCl4 with on-set dehydrogenation about 40 °C.•Modification of dehydrogenation reaction in the 4LiAlH4+ZrCl4 as compared to LiAlH4.
The role of distillation on the quality of tequila Rogelio, Prado-Ramírez; Victor, Gonzáles-Alvarez; Carlos, Pelayo-Ortiz ...
International journal of food science & technology,
August 2005, Volume:
40, Issue:
7
Journal Article
Peer reviewed
Open access
Summary
The role of a batch rectification on the quality of tequila, a traditional Mexican beverage, was studied. It was shown that the official tequila standard composition, particularly the size of ...the slop cuts and the correct balance of flavour constituents, can be determined by monitoring the concentration of the regulated compounds (ethanol, methanol, higher alcohols, ethyl acetate, acetaldehyde and furfural) throughout the rectification process. It was found that these regulated compounds are produced over the same time scales when either stainless steel or copper alembics are used. When distillations were done in copper alembics, however, it was found that the copper content of the rectified product exceeded the amount permitted in the official tequila standards. Finally, we report a comparison of sensory properties of tequila distillates obtained in both copper and stainless steel alembics.
► Ion-exchange resin for Cu removal from Mexican tequila is presented. ► Methanol removed from tequila solution. ► Packed bed with resin reached Cu removal that complies with actual regulations. ► ...Potential of industrial applications in copper and methanol removal from tequila.
An ion-exchange resin was employed to remove copper from tequila. Elemental analysis, batch and column copper uptake measurements were performed to assess the extent of metal removal; FTIR and XPS were employed to elucidate the copper complexes formed on the surface of resin; GC was used to investigate resin fouling and the extent of methanol removal. A modified Langmuir isotherm was used to explain adsorption equilibrium data. A ligand density of 2.21
mmol/g as sulphonic group, was measured. Maximum copper uptake by resin was 0.59
mmol/g. GC results from column experiments revealed methanol changes from 311
mg/100
ml anhydrous alcohol (AA) to 212
mg/100
ml AA, complying with Mexican regulations. Tequila solution with copper (5.3
l, 7.3
mg/l) was treated to breakthrough point in column experiments reaching 0.5
mg/l of copper at effluent. These results comply with the Mexican regulation for copper concentration (⩽2
mg/l) showing the promise of resin for industrial applications in removal of copper and methanol from tequila.
Concentrations of metals such as copper in alcoholic beverages must be strictly regulated due to negative effects ranging from beverage spoilage and hazing, to sensorial and health consequences. In ...this paper, a voltammetric alternative is presented for the analysis of copper in tequila, a Mexican spirituous alcoholic beverage. Anodic Stripping Voltammetry is applied and the standard addition method is used to quantify copper in this beverage at concentrations commonly present in tequila (<10 ppm) without sample pretreatment. Copper can be reduced and then oxidized quantitatively and reproducibly. A comparison of Anodic Stripping Voltammetry with Atomic Absorption Spectrometry is presented.
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