Bleaching Miscanthus x giganteus Acetosolv pulps with hydrogen peroxide/acetic acid. Part 1: Behaviour in aqueous alkaline media
ABSTRACT Miscanthus x giganteus bark samples subjected to fractionation by the Acetosolv process under optimal conditions were bleached using hydrogen peroxide and acetic acid in aqueous media under alkaline conditions. The inﬂuence of the main operational variables in the bleaching of Acetosolv pulps of M. x giganteus (i.e. hydrogen peroxide concentration, 3–7%; temperature, 55–75 ºC; pH 9–11), obtained after treatments, have been assessed on pulp yield, kappa number, viscosity and brightness of bleached pulps. For this purpose, a rotatable and orthogonal second-order factorial design of experiments was used, in order to identify the optimum operating conditions. The obtained empirical mathematical models demonstrate that, in general, the bleaching was efﬁcient, achieving pulps with kappa numbers below 10. The chemical composition and physicochemical properties of the bleached pulps fulﬁlled the requirements for forthcoming bleaching stages. Moreover, an alkaline extraction stage to eliminate saponiﬁable groups of Acetosolv pulps was studied, as well as the necessity of use chelating agents in the stage with hydrogen peroxide.
- SourceAvailable from: Qi-Ning Sun[Show abstract] [Hide abstract]
ABSTRACT: Miscanthus represents a key candidate energy crop for use in biomass-to-liquid fuel-conversion processes and biorefineries to produce a range of liquid fuels and chemicals; it has recently attracted considerable attention. Its yield, elemental composition, carbohydrate and lignin content and composition are of high importance to be reviewed for future biofuel production and development. Starting from Miscanthus, various pre-treatment technologies have recently been developed in the literature to break down the lignin structure, disrupt the crystalline structure of cellulose, and enhance its enzyme digestibility. These technologies included chemical, physicochemical, and biological pre-treatments. Due to its significantly lower concentrations of moisture and ash, Miscanthus also represents a key candidate crop for use in biomass-to-liquid conversion processes to produce a range of liquid fuels and chemicals by thermochemical conversion. The goal of this paper is to review the current status of the technology for biofuel production from this crop within a biorefinery context.Biofuels Bioproducts and Biorefining 07/2012; 6(5):580-598. · 3.77 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The bleaching of semibleached Miscanthus x giganteus Acetosolv pulp, after alkaline and peroxyacetate treatments, was investigated by a novel totally chlorine-free (TCF) sequence. Oxygen deligniﬁcation (O-stage), peroxide (P-stage), and oxygen-pressurized hydrogen peroxide stage (PO-stage) were assayed in order to reach the target values for dissolving pulps. Using factorial experimental designs, we investigated the effects of the bleaching variables on the parameters deﬁning the process and checked the effects after adding chelating agents. Regression equations satisfactorily ﬁtted the experimental results, and under the optimum conditions, a fully bleached pulp (86.9% ISO brightness) with a viscosity of 786 cm 3 /g and a very favorable kappa number (1.3) was obtained. Carbohydrate protectors substantially improved the characteristics of dissolving pulps, but pulps with kappa values above 6 did not improve with carbohydrate protectors as expected.Industrial & Engineering Chemistry Research 04/2009; 48(22):9830-9836. · 2.24 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The behavior of Miscanthus x giganteus bark lipophilic extractives during three acid organosolv pulping processes (Acetosolv, formic acid fractionation, and Milox) was investigated. It was demonstrated that nearly 90% of the lipophilic extractives were removed from pulps by either dissolution in the organosolv liquors (fatty acids and alcohols) or extensive degradation (sterols). The organosolv liquors were found to be rich in vanillin, syringaldehyde, and ferulic, vanillic, and p-coumaric acids. The Acetosolv fractionation process was found to be the most efficient in the removal of lipophilic components from pulps, and it was also the process that generated higher amounts of valuable monomeric phenolic compounds that could be exploited within the biorefinery context.Journal of Agricultural and Food Chemistry 05/2010; 58(14):8279-8285. · 3.11 Impact Factor