Browsing by Author "Zborowski, Charlotte"

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    Adsorptive behavior of phosphorus onto recycled waste biosolids after being acid leached from wastewater sludge
    (Elsevier, 2022-08-15) Kaljunen, Juho Uzkurt; Yazdani, Roza; Al-Juboori, Raed A.; Zborowski, Charlotte; Meinander, Kristoffer; Mikola, Anna; Department of Built Environment; Department of Mechanical Engineering; Department of Bioproducts and Biosystems; Water and Environmental Eng.; Energy Conversion; Bioproduct Chemistry
    A vast amount of phosphorus is being wasted or inefficiently utilized in wastewater treatment sludge worldwide. This paper investigates the adsorptive loading of phosphorus from the sludge on different biosolid materials for potential recovery and after use. The phosphorus was leached with acid from wastewater sludge from a chemical P removal process and adsorbed onto four different waste-based biosolid materials. The four biosolids were biochar, commercial lignin, sludge char (pyrolyzed wastewater treatment sludge), and humus (extracted from black liquor). Among the studied biosolids, loaded sludgechar had the highest phosphorus content, yet all materials performed well in P-adsorption. Optimal leaching and adsorption conditions were identified as pH 3 and adsorbent dosage between 0.5 g/L and 0.61 g/L for all biomaterials. The highest adsorption capacity value reached 400–500 mg/g with temperature-dependence. Biosolid materials were characterized with FT-IR, SEM-EDS, XRF, XRD, and XPS. Mathematical modeling through kinetic adsorption models showed that all biomaterials obey a pseudo first order kinetic model, and pore and intra-particle diffusion contribute to the adsorption mechanisms. The isotherm models suggest that the adsorbents are heterogeneous, and the adsorbate physiochemically bond with the functional groups of adsorbents with different adsorptive energies. The process is temperature-dependent and endothermic. XPS and XRD analyses showed that phosphorus adsorbed on the materials is mostly phosphate bound with Fe and Ca. Overall recovery efficiency was 21% (P bound on biosolids / P in sludge before leaching). Such phosphorus-loaded biomaterials are promising for use as feasible slow-release fertilizers.
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    Combining Rigid Cellulose Nanocrystals and Soft Silk Proteins: Revealing Interactions and Alignment in Shear
    (Wiley-Blackwell, 2023-07-17) Leppänen, Ilona; Arola, Suvi; King, Alistair W.T.; Unger, Miriam; Stadler, Hartmut; Nissen, Gry Sofie; Zborowski, Charlotte; Virtanen, Tommi; Salmela, Juha; Setälä, Harri; Lésage, Stephanie; Österberg, Monika; Tammelin, Tekla; Department of Bioproducts and Biosystems; Bioproduct Chemistry; VTT Technical Research Centre of Finland; Bruker Nano Surfaces Division Germany; Oxford Biomaterials Ltd.; Spinnova Oy
    Natural materials, such as silk and cellulose, have an inspiring set of properties, which have evolved over hundreds of millions of years. In this study, cellulose nanocrystals (CNCs) and regenerated silk fibroin (RSF) are combined to evaluate their suitability for filament formation. This is assessed by tuning and characterizing the interactions between these two materials and finally by studying the alignment of the mixtures under shear. To modify the interactions between CNCs and silk, CNCs with varying surface functionalities (sulfate and/or aminosilane groups) are used. The interactions and compatibility of the two components are investigated using quartz crystal microbalance with dissipation monitoring (QCM-D) and photothermal atomic force microscopy (AFM-IR), which show that ionic interactions induce sufficient binding between the two components. Then, the alignment of the CNC and silk mixtures is evaluated by shear-induced polarized light imaging, which indicates that silk can orientate with the CNCs when not covalently bound. Finally, the potential of the materials for filament formation is tentatively demonstrated using an industrial dry-spinning environment, where CNCs are expected to bring order and alignment, whereas RSF provides soft and more mobile regions to further facilitate the alignment of the final filament structure.