Implanted positive muons with low energies (in the range 1-30 keV) are extremely useful local probes in the study of thin films and multi-layer structures. The average muon stopping depth, typically in the order of tens of nanometers, is a function of the muon implantation energy and of the density of the material, but the stopping range extends over a broad region, also in the order of tens of nanometers. Therefore, an adequate simulation procedure is required in order to extract the depth-dependence of the experimental parameters. Here we present a method to extract depth-resolved information from the implantation energy dependence of the experimental parameters in a low-energy muon spin spectroscopy experiment. The method and corresponding results are exemplified for a semiconductor film, Cu(In,Ga)Se 2 , covered with a thin layer of Al 2 O 3 , but can be applied to any heterostructure studied with low energy muons. It is shown that if an effect is present in the experimental data, the method is an important tool to identify its location and depth extent.

Black liquor (BL) from kraft pulping industries contains a large fraction of lignin and hemicelluloses and their efficient separation can open up new possibilities for integrated biorefineries. In this work, lignin and hemicelluloses were separated from BL and concentrated BL (obtained by ultrafiltration), by precipitation using acidification and antisolvent precipitation method, respectively. For lignin precipitation, different organic acids, namely acetic, lactic and citric acid, were used and the yield and purity of the extracted lignin were compared with the lignin precipitated using inorganic acids, namely sulphuric and phosphoric acid. Among the organic acids, the highest yield of lignin (57.2%) was obtained by lactic acid, but the extract also contained the highest levels of inorganic impurities (9.2%). The extract obtained from acetic acid contained lower inorganic impurities and the lignin yield was 48.1%. The hemicellulose was extracted from BL liquor that was concentrated using the ZnObased PES mixed matrix ultrafiltration membrane, which was started by first separating lignin (at pH 3.5, 4 and 4.5) from it. The supernatants from the lignin precipitation process were used as a source of hemicellulose and this was precipitated by using acetone as an antisolvent. The highest hemicellulose yield (54.4%) was obtained from the supernatant with the lowest lignin content and highest acetone to supernatant ratio. Keywords: acidification, antisolvent precipitation, hemicelluloses, kraft black liquor, lignin