11 research outputs found
Using alkali metals to control reactivity and porosity during physical activation of demineralised kraft lignin
Demineralised kraft lignin was impregnated with between 6.2% and 50% NaCl or KCl and
physically activated in CO2 at 750 C. The results presented show that a considerable reduction
in activation time even at a comparatively low activation temperature could be
achieved, particularly when using KCl. Considering a fixed level of burn-off, the impregnation
did not affect the pore volume and only increased the pore width by about 0.1–0.2 nm,
depending on the concentration of NaCl or KCl used. By controlling the conditions it was
possible to obtain predominantly ultramicroporous materials with mean pore widths over
the range 0.53–0.77 nm. On the other hand, at high levels of burn-off there was evidence for
micropore widening into the small mesopore range and also for the formation of a secondary
mesopore structure. Under these conditions it was possible to obtain materials with
pore volumes as high as 0.82 cm3 g 1
Low-Cost Adsorbents: Growing Approach to Wastewater Treatment—a Review
Industrial, agricultural, and domestic activities of humans have
affected the environmental system, resulting in drastic problems
such as global warming and the generation of wastewater containing
high levels of pollutants. As water of good quality is a precious
commodity and available in limited amounts, it has become
highly imperative to treat wastewater for removal of pollutants. In
addition, the rapid modernization of society has also led to the
generation of huge amount of materials of little value that have no
fruitful use. Such materials are generally considered as waste, and
their disposal is a problem. Also, there are some materials that are
available in nature that have little or no use. The utilization of all
such materials as low-cost adsorbents for the treatment of wastewater
may make them of some value. An effort has been made to
give a brief idea of an approach to wastewater treatment, particularly
discussing and highlighting in brief the low-cost alternative
adsorbents with a view to utilizing these waste/low-cost materials
Characterization of Wood-based Industrial Biorefinery Lignosulfonates and Supercritical Water Hydrolysis Lignin
Understanding the properties of any particular biorefinery or pulping residue lignin is crucial when choosing the right lignin for the right end use. In this paper, three different residual lignin types [supercritical water hydrolysis lignin (SCWH), ammonium lignosulfonate (A-LS), and sodium lignosulfonate (S-LS)] were evaluated for their chemical structure, thermal properties and water vapor adsorption behavior. SCWH lignin was found to have a high amount of phenolic hydroxyl groups and the highest amount of beta-O-4 linkages. Combined with a low ash content, it shows potential to be used for conversion into aromatic or platform chemicals. A-LS and S-LS had more aliphatic hydroxyl groups, aliphatic double bonds and C=O structures. All lignins had available C-3/C-5 positions, which can increase reactivity towards adhesive precursors. The glass transition temperature (T-g) data indicated that the SCWH and S-LS lignin types can be suitable for production of carbon fibers. Lignosulfonates exhibited considerable higher water vapor adsorption as compared to the SCWH lignin. In conclusion, this study demonstrated that the SCWH differed greatly from the lignosulfonates in purity, chemical structure, thermal stability and water sorption behavior. SCWH lignin showed great potential as raw material for aromatic compounds, carbon fibers, adhesives or polymers. Lignosulfonates are less suited for conversion into chemicals or carbon fibers, but due to the high amount of aliphatic hydroxyl groups, they can potentially be modified or used as adhesives, dispersants, or reinforcement material in polymers. For most value-adding applications, energy-intensive purification of the lignosulfonates would be required.Open access funding provided by Linnaeus University. Venla Hemmila and Stergios Adamopoulos would like to thank the Knowledge Foundation for the financial support (project titled "New environment-friendly board materials", 2015-2019). Arantxa Eceiza thanks the Basque Government (IT776-16) and SgiKer General Services of the University of the Basque Countr