Jaime Rodríguez

Estimating the chemical composition of biodegraded pine and eucalyptus wood by DRIFT spectroscopy and multivariate analysis.

Abstract Fourier transformed infra-red (FTIR) was evaluated as an analytical tool for monitoring wood biodegradation. A sample set containing typical soft (Pinus radiata) and hardwood (Eucalyptus globulus) decayed by six white- and two brown-rot fungi was prepared. Biodegradation times from 30 days to 1 year provided samples that suffered weight losses varying from 0.4% to 36% for pine wood and 1.7% to 42% for eucalyptus wood. Decayed samples were characterized by conventional wet chemical analysis and by diffuse reflectance FTIR (DRIFT) spectroscopy. Multivariate analysis was applied to correlate chemical composition in wood samples with the FTIR spectral data. Partial least squares (PLS) models were able to predict the major wood components’ concentrations at the 99% confidence level presenting r2 values higher than 0.86 in most cases. Models for P. radiata were more precise than for E. globulus.

Photocatalytic degradation of cellulose bleaching effluent by supported TiO2 and ZnO

A cellulose bleaching effluent (E1) was degraded in batch conditions by photocatalysis using TiO2 and ZnO supported on glass Raschig rings. The effluent was completely decolourised and the total phenol content was reduced by 85% after 120 min treatment with both catalysts. Partial mineralization of the organic matter was confirmed by total organic carbon (TOC) reduction, approximately 50%. The residual organic matter shows a low acute toxicity as compared to the initial values and AOX values are strongly reduced after the photocatalytic oxidation. Molecular mass distribution showed that high molecular mass compounds were almost completely degraded.

EDTA: THE CHELATING AGENT UNDER ENVIRONMENTAL SCRUTINY

The chelating agent EDTA (ethylenediaminetetraacetic acid) is a compound of massive use world wide with household and industrial applications, being one of the anthropogenic compounds with highest concentrations in inland European waters. In this review, the applications of EDTA and its behavior once it has been released into the environment are described. At a laboratory scale, degradation of EDTA has been achieved; however, in natural environments studies detect poor biodegradability. It is concluded that EDTA behaves as a persistent substance in the environment and that its contribution to heavy metals bioavailability and remobilization processes in the environment is a major concern.

Advanced oxidation of a pulp mill bleaching wastewater.

The degradation, by several advanced oxidation reactions, of a pulp mill ECF bleaching effluent, was studied. The initial biodegradability of the organic matter present in the effluent, estimated as the BOD5/COD, was low (0.3). When the effluent was submitted to ozonation and to five different advanced oxidation systems (O3/UV, O3/UV/ZnO, O3/UV/TiO2, O2/UV/ZnO, O2/UV/TiO2), the biodegradability increase significantly. After five minutes of reaction, the O3/UV system appears as the most efficient in to transform the organic matter to more biodegradable forms. A similar effect was observed when the effluent was submitted to an activated sludge treatment. The COD, TOC and toxicity reduction correlated well with the biodegradability enhancement after AOPs treatments.

Biodegradation of Pinus radiata softwood by white- and brown-rot fungi

The weight and component losses of Pinusradiata wood after decay by six species of white-rot and two species of brown-rot fungi for periods varying from 30 to 360 days were evaluated. Three groups of decayed wood samples were identified based on the principal component analysis (PCA) of the data on their weight and component losses. Selective lignin degradation was produced by Ceriporiopsissubvermispora and Punctulariaatropurpurascens within different periods, the longest one lasting 90 days, and also by Meruliustremellosus after 90 days of biodegradation. Comparing the data on biodegradation of P.radiata by Trametesversicolor with the ones reported for biodegradation of Eucalyptusglobulus and E.grandis indicated that P.radiata is as susceptible to wood decay by this white-rot fungus as the two types of hardwood.

Homogeneous and heterogeneous advanced oxidation of a bleaching effluent from the pulp and paper industry

The degradation of phenolic and polyphenolic compounds present in a bleaching ECF effluent for different advanced oxidation systems is described. Photocatalysis with O 2 /ZnO/UV, O 2 /TiO 2 /UV were demonstrated to be the best systems to oxidize the effluent in a short period of time. The homogeneous systems O 3 and O 3 /UV also degrade the organic matter but at a lower extent considering the same time of reaction. Reactions were monitored by color changes, pH, COD and BOD.

Enhanced hydroxyl radical production by dihydroxybenzene-driven Fenton reactions: implications for wood biodegradation.

Brown rot fungi degrade wood, in initial stages, mainly through hydroxyl radicals (•OH) produced by Fenton reactions. These Fenton reactions can be promoted by dihydroxybenzenes (DHBs), which can chelate and reduce Fe(III), increasing the reactivity for different substrates. This mechanism allows the extensive degradation of carbohydrates and the oxidation of lignin during wood biodegradation by brown rot fungi. To understand the enhanced reactivity in these systems, kinetics experiments were carried out, measuring •OH formation by the spin-trapping technique of electron paramagnetic resonance spectroscopy. As models of the fungal DHBs, 1,2-dihydroxybenzene (catechol), 2,3-dihydroxybenzoic acid and 3,4-dihydroxybenzoic acid were utilized as well as 1,2-dihydroxy-3,5-benzenedisulfonate as a non-Fe(III)-reducing substance for comparison. Higher amounts and maintained concentrations of •OH were observed in the driven Fenton reactions versus the unmodified Fenton process. A linear correlation between the logarithms of complex stability constants and the •OH production was observed, suggesting participation of such complexes in the radical production.

Characterization of white zones produced on Pinus radiata wood chips by Ganoderma australe and Ceriporiopsis subvermispora

White zones produced on biodegraded Pinus radiata wood chips were characterized by micro-localized-FTIR (Fourier Transformed Infra Red) spectroscopy and scanning electron microscopy. Both techniques permitted assignment of the white zones to a selective lignin removal process. Although both fungi studied have degraded lignin selectively in these restricted superficial areas, chemical analysis of the wood chips indicated that Ganoderma australe removed 16% of the initial amount of glucan at the 20% weight loss level. Ceriporiopsis subvermispora did not remove glucan at weight loss values below 17%. Prolonged biodegradation resulted in reduction of white zones by G. australe, and increased white zones from C. subvermispora decayed samples.

Evaluation of a combined brown rot decay–chemical delignification process as a pretreatment for bioethanol production from Pinus radiata wood chips

Wood chips of Pinus radiata softwood were biotreated with the brown rot fungus (BRF) Gloeophyllum trabeum for periods from 4 and 12xa0weeks. Biodegradation by BRF leads to an increase in cellulose depolymerization with increasing incubation time. As a result, the intrinsic viscosity of holocellulose decreased from 1,487xa0cm3/g in control samples to 783 and 600xa0cm3/g in 4- and 12-week decayed wood chips, respectively. Wood weight and glucan losses varied from 6 to 14% and 9 to 21%, respectively. Undecayed and 4-week decayed wood chips were delignified by alkaline (NaOH solution) or organosolv (ethanol/water) processes to produced cellulosic pulps. For both process, pulp yield was 5–10% lower for decayed samples than for control pulps. However, organosolv bio-pulps presented low residual lignin amount and high glucan retention. Chemical pulps and milled wood from undecayed and 4-week decayed wood chips were pre-saccharified with cellulases for 24xa0h at 50°C followed by simultaneous saccharification and fermentation (SSF) with the yeast Saccharomyces cerevisiae IR2-9a at 40°C for 96xa0h for bioethanol production. Considering glucan losses during wood decay and conversion yields from chemical pulping and SSF processes, no gains in ethanol production were obtained from the combination of BRF with alkaline delignification; however, the combination of BRF and organosolv processes resulted in a calculated production of 210xa0mL ethanol/kg wood or 72% of the maximum theoretically possible from that pretreatment, which was the best result obtained in the present study.

Formic acid/acetone-organosolv pulping of white-rotted Pinus radiata softwood†

Organosolv pulping of fungally pretreated samples of Pinus radiata was evaluated. A screening study using five white-rot fungi indicated that Ceriporiopsis subvermisopora and Punctularia artropurpurascens were the most selective ones for lignin degradation. These fungi were further cultured in bioreactors containing 2.5 kg of wood chips. Fungally-pretreated samples were delignified by formic acid/acetone (7:3) at 150°C. Pulping kinetics and strength properties of the resulting unbleached pulps were evaluated. Delignification rates and xylan solubilization rates were higher for the decayed samples than for the undecayed control, except for the sample biotreated with P. artropurpurascens for 30 days. C. subvermispora proved appropriate for treating the wood samples before organosolv pulping, since pretreatment with this fungus resulted in faster wood delignification and pulps with lower residual lignin. Increases in tensile index ranging from 3% to 22% were observed for most pulps prepared from biotreated samples, independently both of the fungal species used in the pretreatment and of the extent of the wood biodegradation expressed as wood weight loss. However, tear and burst indexes and brightness were lower than or similar to those of pulps prepared from the undecayed control.