The U.S. pulp and paper industry uses large quantities of water to produce cellulose pulp from trees. The water leaving the pulping process contains a number of organic byproducts and inorganic chemicals. To reuse the water and the chemicals, paper mills rely on steam-fed evaporators that boil up the water and separate it from the chemicals.
Water separation by evaporators is effective but uses large amounts of energy. That’s significant given that the United States currently is the world’s second-largest producer of paper and paperboard. The country’s approximately 100 paper mills are estimated to use about 0.2 quads (a quad is a quadrillion BTUs) of energy per year for water recycling, making it one of the most energy-intensive chemical processes. All industrial energy consumption in the United States in 2019 totaled 26.4 quads, according to Lawrence Livermore National Laboratory.
An alternative is to deploy energy-efficient filtration membranes to recycle pulping wastewater. But conventional polymer membranes — commercially available for the past several decades — cannot withstand operation in the harsh conditions and high chemical concentrations found in pulping wastewater and many other industrial applications.
Georgia Institute of Technology researchers have found a method to engineer membranes made from graphene oxide (GO), a chemically resistant material based on carbon, so they can work effectively in industrial applications.
Read more at Georgia Institute of Technology
Image: Paper mills use large amounts of water in their production processes and need new methods to improve sustainability. (Credit: Georgia Tech)