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Lignin can be precipitated from kraft black liquor (BL) through the addition of an acidifying agent such as carbon dioxide or sulfuric acid. In most of the existing lignin precipitation processes that are using acid addition, sufficient acid is added to drop the pH of the black liquor from about 13−14 to about 9−10, followed by lignin particle coagulation, lignin slurry filtration, and lignin cake washing with sulfuric acid and water. At pH values of less than 11, the potential exists for the generation of significant quantities of totally reduced sulfur (TRS) compounds and other volatile sulfur species. Such compounds which include hydrogen sulfide, methyl mercaptan, dimethyl sulfide, and dimethyl disulfide are strongly odorous compounds with well-known negative effects on human health and other forms of life. To address this problem, as well as other problems associated with existing lignin recovery processes, FPInnovations and Noram recently developed a new process called the LignoForce System. This process employs a black liquor oxidation step to convert TRS compounds present in kraft black liquor to nonvolatile species. This paper discusses the applicability of the LignoForce System to several feedstock black liquors (e.g., softwood, hardwood, and eucalyptus) as well as the sulfur compound outgassing potential from various stages of this process compared to a reference case in which the black liquor was not oxidized. In addition, the emission of volatile sulfur and organic compounds from the two lignin products at different temperatures is discussed and compared.

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Nanoporous PtIr bimetallic electrocatalysts with different contents of iridium ͑Ir%: 15, 28, 40, and 50͒ were prepared using a one-step facile hydrothermal method. Formaldehyde was used as the reduction agent to simultaneously reduce Ir 3+ and Pt 4+ , resulting in the formation of bimetallic PtIr nanoporous structures. Scanning electron microscopy and energy dispersive X-ray spectroscopy were employed to characterize the surface morphology and composition of the as-synthesized samples. A number of electrochemical methods were used to study the electrochemical activity of the different nanoporous PtIr electrodes toward methanol oxidation and oxygen reduction. Our electrochemical studies show that the synthesized nanoporous PtIr electrodes possess extraordinarily high electroactive surface areas and that the presence of Ir significantly improves the electrocatalytic activity of Pt toward the electrochemical oxidation of methanol and the electrochemical reduction of oxygen. Of the synthesized nanoporous PtIr electrodes, the Pt 60 Ir 40 electrode exhibits the highest electrocatalytic activity. The steady-state current density of the nanoporous Pt 60 Ir 40 electrode for methanol oxidation at 0.6 V is 345 times higher than that of a polycrystalline Pt electrode and over four times higher than that of a nanoporous Pt electrode Methanol oxidation and oxygen reduction are key anodic and cathodic reactions in direct methanol fuel cells ͑DMFCs͒. Platinum electrocatalysts have shown high electrocatalytic activity toward methanol oxidation. However, one of the major drawbacks of using pure Pt electrodes is that their performance is limited by the formation of strongly absorbed intermediate CO on the electrode surface. 1-4 The development of electrode materials with higher activity will help to increase the efficiency of the DMFC. Over the last two decades, investigations in this field have been focusing on the development of Pt-based electrocatalysts, such as Pt-based bimetallic alloys, nanoparticle mixtures, and composites. A wide variety of other metals coupled with platinum to form Pt-based electrocatalysts have been synthesized and tested, including Au, 5 Co, 3 Ni, 3,6 Ru, 7-12 Mo, 13 W, 14,15 Ir, 16,[17][18][19][20] These studies have demonstrated that the Pt-based bimetallic electrodes have enhanced electrocatalytic activity over bulk platinum electrodes. In addition to methanol oxidation, the oxygen reduction reaction ͑ORR͒ has been widely investigated due to the application of oxygen cathodes in electrochemical energy conversion systems, including fuel cells. [21][22][23][24][25] Although investigations into the kinetics and mechanism of the ORR have confirmed that platinum is the best electrocatalyst among pure metals for the reaction, practical applications involving large amounts of platinum are hampered by the high cost of platinum. Recent efforts have focused on improving the catalytic effectiveness of platinum by dispersing the catalyst particles onto an electrode support with a high surface area and forming all...

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