Future technologies for isolation and reactive separation of constituents from pulping effluents

At the United Nations Climate Change Conference 2015 in Paris the members agreed on reducing their carbon output "as soon as possible" and to do their best to keep global warming "to well below 2 degrees C". The goal of global warming beneath 2°C can just be reached if between 2000 and 2050 the cumulative carbon emission is limited to 1.100 Gt CO2. At the moment the annual CO2 emission amounts 36 Gt CO2. With this capacity limit and production rate CO2 emission may be switched off in 2027.
To reach the goal of 2°C earth warming the Paris agreement further comprises to exit the use of fossil fuels [1]. The phase-out of fossil fuels entails that new technologies must be developed, process intensification has to be applied in all fields of industrial production and state of the art technologies have to be re- boarded with new technologies. Main obstacle of the biorefinery is the economic feasibility, which can be addressed either by a fair valuation basis or/and by new technologies and processes. Fair valuation basis is a political topic. Research has to address technical topics. New technologies and processes have to suffice economic and ecological aspects.
As early as in the late 19th century, research activities on usage of waste from the pulp and paper industry are reported [2], [3]. In the 1920s and 1930s first industrial size plants were built for the production of furfural and for the recovery of lignin; lignin was then used as dispersing agent. US patent 2.050.400, dating back to the year 1930, claims a method for the recovery of heat and chemicals from waste products from industrial processes such as alcohol [4]. In 1940 already P. von Walden [5] addressed a still fashionable topic: How long the national economy can tolerate to classify lignin as wastage? In conclusion the pulp and paper industry has been the focus and lead in industrial biorefinery for centuries. Referring to the Paris Agreement several technologies and products, covering a span from low molecular weight constituents such as ethanol, carboxylic acids or furfural to product blends like turpentine and tall oil may seemingly just need reevaluation of the market potential, arising the question, weather there is any need for future research activities left?
Membrane separations is a fairly new technology in processing effluents from pulping [6], targeting dissolved macromolecular constituents such as lignin. New technologies for intensified carboxylic acid isolation have become subject of intensive investigation. Investigation of hydrogenation and hydro-deoxygenation of black liquor is under way.
Reactive separation with supported liquid membranes has not been applied in the processing of effluents from pulping. Liquid membrane permeation, well established in the hydrometallurgy [7], offers challenging technological features for application in isolating value-added products from effluents with complex matrix. The rigid surface is highly tolerant against suspended solids. Since cross flow operation is applied, fouling as well as scaling is not an issue of process stability limiting significance. The flexibility in membrane composition gives access to the transfer of non-ionogenic as well as ionogenic species. Even highly water soluble solvents, reactants and catalysts may be applied without need of raffinate treatment, since loss of solvent is limited by the physical barrier of the membrane. Finally the concept of triple liquid operation has to be mentioned. Triple liquid operation gives access to reactive separation of constituents from competing processes. Liquid membrane separation with supported membranes therefore offers great potential in future oriented applications in the biorefinery.

[1] C. McGlade and P. Ekins, “The geographical distribution of fossil fuels unused when limiting global warming to 2 °C,” Nature, vol. 517, no. 7533, pp. 187–190, 2015.
[2] B. Kamm, P. Gruber, and M. Kamm, “Biorefineries–Industrial Processes and Products,” Ullman’s Encycl. Ind. Chem., vol. 5, pp. 659–688, 2007.
[3] N. A. Engineering, The Ecology of Industry: Sectors and Linkages. Deanna Richards, Greg Pearsonq, 1998.
[4] C. L. Wagner, “Method for Recovery of heat an dchemicals from waste products,” 2,050,400, 1930.
[5] W. Paul, Geschichte der organischen Chemie seit 1880, Unveränd. . Berlin: Springer, 1990.
[6] L. Y. Jiang and J. M. Zhu, “Separation technologies for current and future biorefineries — status and potential of membrane-based separation,” vol. 2, no. December, pp. 673–690, 2013.
[7] M. Siebenhofer, H. Noll, and M. Fritz, “Liquid Membrane Permeation with Supported Liquid Membranes and their Application in Li-ion Battery Recycling,” Sep. Sci. Technol., vol. 50, no. 18, pp. 2937 – 2947, 2015.