Tag Archive for: AWS SNS 000043 A

Publication on AWSensors technology

Methods for Calibrating the Electrochemical Quartz Crystal Microbalance: Frequency to Mass and Compensation for Viscous Load

/in , , /by

Authors: Claes-Olof A. Olsson, Anna Neus Igual-Muñoz and Stefano Mischler

Journal: Chemosensors (2023)

 

Abstract

The main output from an Electrochemical Quartz Crystal Microbalance is a frequency shift. This note describes how to separate the mass- and viscous load contributions to this shift by a calibration procedure. The mass calibration is made by electroplating from a copper sulfate solution in ethanol/water with 100% current efficiency. An estimate of viscous load is obtained by measuring the energy dissipation and is related to frequency change using the Kanazawa–Gordon equation. Two approaches are discussed: either by performing calibration experiments in a series of water–glycerol mixtures or by following oscillations in frequency and dissipation by collecting data during the stabilization phase of the experiment.

 

You may read the full paper here.

Publication on AWSensors technology

Fouling of Reverse Osmosis Membrane with Effluent Organic Matter: Componential Role of Hydrophobicity

/in , , /by

Authors: Noa Stein, Revital Sharon-Gojman, Meagan S. Mauter, Roy Bernstein and Moshe Herzberg

Journal: ACS ES&T Water (2023)

 

Abstract

Organic matter dissolved in tertiary effluents (effluent organic matter, EfOM) is the predominant organic membrane foulant in tertiary wastewater reverse osmosis (RO) desalination, ultimately causing biofouling. The interrelated effects of EfOM fractions of different hydrophobicity and polarity on membrane performance were studied by (i) examining each fraction’s overall effect on membrane permeability; (ii) analyzing the intrinsic hydraulic resistance induced by each fraction; (iii) studying their adsorption on the active layer of an RO membrane using a quartz crystal microbalance with dissipation monitoring (QCM-D); (iv) assessing their “dry” molecular mass when adsorbed on polyamide using localized surface plasmon resonance (LSPR) sensing; (v) analyzing their hydrodynamic radii by dynamic light scattering (DLS); and (vi) characterization using excitation–emission matrix (EEM) analysis and parallel-factor (PARAFAC) modeling. Hydrophobic and transphilic neutral fractions (containing ∼12.5% total organic carbon) have the greatest effect on membrane flux reduction and the highest hydraulic resistance and adhere most strongly to polyamide surfaces, resulting in the highest adsorbed “dry” mass. Therefore, in terms of their effect on RO permeate flux reduction, these fractions are the most detrimental in the EfOM mix. EEM analysis and associated PARAFAC modeling indicate that the main components causing this effect are mixtures of protein-like compounds, together with humic-like substances. Novel LSPR-based analysis elucidated the role of the fractions most detrimental to membrane permeability through measurement of dry mass surface concentration on a polyamide mimetic sensor. This study provides valuable insights into the roles of different EfOM fractions in RO membrane fouling and enhances our understanding of fouling during tertiary wastewater desalination.

Fouling of Reverse Osmosis Membrane with Effluent Organic Matter: Componential Role of Hydrophobicity

 

You may read the full paper here.

Publication on AWSensors technology

Tuning the water interactions of cellulose nanofibril hydrogels using willow bark extract

/in , , /by

Authors: Ngoc Huynh, Juan José Valle-Delgado, Wenwen Fang, Suvi Arola, Monika Österberg

Journal: Carbohydrate Polymers (2023)

 

Abstract

Cellulose nanofibrils (CNFs) are increasingly used as precursors for foams, films and composites, where water interactions are of great importance. In this study, we used willow bark extract (WBE), an underrated natural source of bioactive phenolic compounds, as a plant-based modifier for CNF hydrogels, without compromising their mechanical properties. We found that the introduction of WBE into both native, mechanically fibrillated CNFs and TEMPO-oxidized CNFs increased considerably the storage modulus of the hydrogels and reduced their swelling ratio in water up to 5–7 times. A detailed chemical analysis revealed that WBE is composed of several phenolic compounds in addition to potassium salts. Whereas the salt ions reduced the repulsion between fibrils and created denser CNF networks, the phenolic compounds – which adsorbed readily on the cellulose surfaces – played an important role in assisting the flowability of the hydrogels at high shear strains by reducing the flocculation tendency, often observed in pure and salt-containing CNFs, and contributed to the structural integrity of the CNF network in aqueous environment. Surprisingly, the willow bark extract exhibited hemolysis activity, which highlights the importance of more thorough investigations of biocompatibility of natural materials. WBE shows great potential for managing the water interactions of CNF-based products.

 

Cellulose nanofibrils (CNFs) are increasingly used as precursors for foams, films and composites, where water interactions are of great importance. In this study, we used willow bark extract (WBE), an underrated natural source of bioactive phenolic compounds, as a plant-based modifier for CNF hydrogels, without compromising their mechanical properties. We found that the introduction of WBE into both native, mechanically fibrillated CNFs and TEMPO-oxidized CNFs increased considerably the storage modulus of the hydrogels and reduced their swelling ratio in water up to 5–7 times. A detailed chemical analysis revealed that WBE is composed of several phenolic compounds in addition to potassium salts. Whereas the salt ions reduced the repulsion between fibrils and created denser CNF networks, the phenolic compounds - which adsorbed readily on the cellulose surfaces - played an important role in assisting the flowability of the hydrogels at high shear strains by reducing the flocculation tendency, often observed in pure and salt-containing CNFs, and contributed to the structural integrity of the CNF network in aqueous environment. Surprisingly, the willow bark extract exhibited hemolysis activity, which highlights the importance of more thorough investigations of biocompatibility of natural materials. WBE shows great potential for managing the water interactions of CNF-based products.

 

You may read the full paper here.