Joseph M. Genco

Mechanisms of oxidative degradation of carbohydrates during oxygen delignification. I. Reaction of methyl β-D-glucopyranoside with photochemically generated hydroxyl radicals.

Abstract Hydroxyl radical is considered to be the major species causing degradation of carbohydrates during oxygen delignification. In this study, reactions involving a carbohydrate model compound and either photochemically generated hydroxyl radical or superoxide from potassium superoxide were carried out to investigate the cleavage of glycosidic linkages. Experiments show that hydroxyl radicals are responsible for the degradation of glycosidic linkages in methyl β-D-glucopyranoside by a substitution reaction displacing D-glucose. Once the glycosidic linkage is broken, reducing carbohydrates undergo a series of reactions forming aldonic acids and lower order aldoses. Control experiments established that no reaction occurs in the absence of UV light under otherwise identical conditions.

MECHANISMS OF OXIDATIVE DEGRADATION OF CARBOHYDRATES DURING OXYGEN DELIGNIFICATION. II. REACTION OF PHOTOCHEMICALLY GENERATED HYDROXYL RADICALS WITH METHYL β-CELLOBIOSIDE

Reactions involving methyl β-cellobioside and several oxygen species were used to investigate cleavage of glycosidic linkages in cellulose by reaction with photochemical hydroxyl radicals. The intent is not to reproduce delignification conditions, but rather to study the specific behavior of carbohydrate models toward hydroxyl radical. Experiments show that hydroxyl radicals are responsible for the degradation of glycosidic linkages in methyl β-cellobioside by substitution reactions displacing cellobiose, D-glucose, methyl β-D-glucoside, and methanol. Once the glycosidic linkages are broken, the reducing carbohydrates undergo a series of reactions forming aldonic acids and lower order aldoses in the same manner as described previously.[1]

The effect of a chelator mediated Fenton system on the fiber and paper properties of hardwood kraft pulp

ABSTRACT Research was conducted into the effect of a chelator-mediated free radical treatment (CMT) on drainage rate, strength properties, optical properties, and fiber morphology for a fully bleached hardwood kraft pulp. The nature of the pulp furnish, specifically the fines and microfibril content, and its gross fiber characteristics, had a significant effect on the final fiber and paper properties. This was primarily due to an increase in the specific surface area of small fibers and fines in the beaten pulp. Treatments with high concentrations of Fenton reagents displayed severe damage to the cellulose fibers in both the beaten and unbeaten pulp. However, under relatively mild reaction conditions, fiber surface fibrillation of the unbeaten virgin fibers occurred. This observation was confirmed through results showing increased pulp tensile strength after treatment. *This is paper 2582 of the Maine Agricultural and Forest Experiment Station.

Sorption of SO2 on Ground Nahcolite Ore

Large quantities of nahcolite ore, a naturally occurring mineral containing between 70 and 90% sodium bicarbonate are known to occur in the Green River Formation of the Piceance Creek Basin of northwestern Colorado.1 Deposits occur in two major forms, as either bedded or disseminated ore. In the latter case, the host rock is oil shale, a dolomitic marlstone containing kerogen material. Bench and pilot scale studies have shown finely divided nahcolite ore to be an effective SO2 sorbent in baghouse filters.2 These studies form the basis of the nahcolite ore injection process as a means for controlling SO2 emissions to the environment.3 Although there have been published investigations of reactions of SO2 with Na2CO3and NaHCO3, 4 no reference could be found to a systematic study of nahcolite ore reacting with SO2.

The Use of Nahcolite Ore and Bag Filters For Sulfur Dioxide Emission Control

This paper describes some technical and economic aspects of the nahcolite ore injection process for the simultaneous removal of fly ash and sulfur oxides from stack gases. The process is capable of removing greater than 99% of the particulate matter and greater than 70% of the sulfur oxides present in such gases. In the process, nahcolite ore, a naturally occurring material containing 70 to 90% sodium bicarbonate, is ground to 90% passing through —200 mesh screens. Approximately 20% of the ground ore is used to precoat the filter bags in a baghouse filter while the remainder of the material is fed into the flue gas Just ahead of the baghouse. The flue gas is drawn through the baghouse by induced draft fans and sent up the stack. Most of the SO2 and practically all of the fly ash in the flue gas can be removed as the gas passes through the filter bags. The spent nahcolite ore and fly ash are collected and conveyed to waste disposal as landfill, or alternatively processed for insolubilization by coprecipita...