WP1 deals with identifying and developing different tailored functionalized materials for use as filters. Key questions involve development of materials with functionally-enhanced natural and engineered porous materials, synthesis, refining, functionalization, characterization and structuring. A vital question is how to integrate stimuli-responsive functions through targeted chemical functionalization and/or structuring.

Involved partners: SU, KTH, UU, RISE, MoRe Research, Disruptive Materials
WP 1 Leader SU (Hedin)
 

Below is a summary on activities performed during 2018.

Materials for removal of heavy metal ions

This task includes investigation of materials for selective adsorption of heavy metal ions and modification of activated carbon for enhancement of capacitive device performance.

Amine modification of mesoporous magnesium carbonate (UU) has been developed as a sorbent for azo dye removal from wastewaters. This work was published recently in ACS Omega https://pubs.acs.org/doi/10.1021/acsomega.8b03493. Work is performed towards mesoporous inorganic carbonates for high temperature CO2 capture and a paper has been drafted. Two Masters students have started in January 2019 and their theses are on the heavy metal removal using inorganic carbonates and the removal of pharmaceutics using inorganic carbonates.

Modifications of the capacitance of carbon electrodes of a typical capacitive de-ionisation device is performed (KTH). Hexagonal boron nitride (h-BN) is well-known high band-gap material (5.9 eV), that has high resistant to dielectric breakdown. Preliminary characterization of the h-BN nanoflakes and the electrode modification was performed with scanning electron microscopy (SEM) and Raman spectroscopy, Figure 1.

Figure 1. a) SEM image of unmodified activated carbon cloth fibres; b) SEM image of carbon cloth fiber after coating with h-BN nanoflakes; c) cross section view of the carbon cloth fiber with the h-BN flakes visible at its outer surface; d) Raman spectra of h-BN flakes-red and blue traces are from h-BN nanoflakes and the green traces are from bulk h-BN. (not to be published elsewhere).

The coating process is being optimised, to obtain a more homogeneous coating, especially in the corners between the weaves of the carbon fibres. Preliminary electrochemical C-V measurements carried out at KTH did not show any increase in specific capacitance possibly due to inhomogeneous coating as well as detachment of the h-BN flakes from the carbon cloth. At RISE, efforts will now focus on the development of an aerosol-based method to coat the carbon cloth to obtain an integral coating in order to achieve the target of increasing specific capacitance of the devices.

Surface modification of cellulose versions and hybrids with hemicellulose

The research work in this task has involved the preparation and characterization of lignocellulose nanoparticles, and their functionalization with zwitterionic polymers. Nanoparticles were extracted with high-pressure homogenization from the residue of a bioethanol pilot plant, which has been reported to consist of crystalline cellulose and lignin. Prior to the mechanical treatment, the material was partially bleached to be able to remove part of the lignin. Residual lignin is expected to improve on the adsorption performance of the material and provide chemical groups useful for functionalization. The nanoparticles were functionalized by grafting of zwitterionic sulfobetaine polymers providing high adsorptivity towards heavy metal ions and metalloids. Bi-layered membranes were prepared with cellulose microfibers as support layer and the zwitterionic lignocellulose as the functional layer.

The work in this task started in January 2018 and planned to last 30 months. One PhD student is involved.

Self-organized wet-stable nanocellulose functionalized aerogels

Studies on how different preparation processes affect the properties of porous, light-weight cellulosic materials have been done, to select special material structures for given end-use applications. Further, suitable candidate contaminants will be selected for additional studies. By including electrically conducting materials, such as nanocarbons or conducting polymers, further material smartness will be demonstrated.

Different methods to control the pore size in nanocellulose aerogel particles have been in focus for the work at RISE.

Activated carbons and porous polymers derived from relevant biomass and waste

Refined hydrochars have been prepared, starting with the preparation of activated carbons and from glucose and amines/polyamines. One manuscript on the valorization of waste milk by hydrothermal carbonization has been prepared and is to be submitted.

Unexpected result

During the preparation of iron impregnated activated carbons for the preparation of magnetically activated carbon for water purification applications, an unexpected result occurred.

As shown in Figure 2., one of the hydrochars had a golden-like luster. A thin film had been deposited on the assembly of hydrochar particles. The size of those particles was gradually increasing when going down in the particles’ assembly. Those at the bottom had diameters of about 5 micrometer while those at the top were about 1 micrometer in top. Further studies are undertaken to rationalize the golden luster and the ordered carbon spheres.

Apart from the unexpected results, which may have applications in water purification and gas separation processes, our objective is to prepare magnetically activated carbon which can be manipulated by a magnetic field.

Figure 2 (left) Golden-like luster of the hydrochar, (middle) cross sectional SEM image zoom in, (right) cross sectional SEW image. (do not use elsewhere, high quality images can be provided later).

So far, glucose had been used as the carbon precursor. The prepared samples did not show any response to a magnetic field which means iron is not impregnated (EDS shows less than 0.08w %) in the prepared samples. Other sources or changes in the work up procedure will be tested.

Publications

Amine-Modified Mesoporous Magnesium Carbonate as an Effective Adsorbetn for Azo Dyes, https://pubs.acs.org/doi/10.1021/acsomega.8b03493

Students
Master Thesis by Stivan Sabir “Minimizing pore size of nanocellulose aerogel particles”.

2019
Two Masters students have started in January 2019 and their theses will cover heavy metal removal using inorganic carbonates and the removal of pharmaceutics using inorganic carbonates. Presentable results from the thesis students are expected later in 2019. Together with MORE, UU is testing different protocols for producing papers with inorganic carbonates embedded. The results are so far very preliminary now but we are in continuous discussion. Discussions with Camfil, and UU is to be sending samples for testing soon.