Tag Archive for: Ti/Au electrode

Publication on AWSensors technology

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

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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

 

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Publication on AWSensors technology

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

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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.

Scientific publication

Electropolymerization of thiazole derivatives bearing thiophene and selenophene and the potential application in capacitors

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Authors: Seongjun Hong, Joon Ho Yoon, Seunghyun Jeong, Yang-Rae Kim and In Tae Kim.
Journal: Journal of Electroanalytical Chemistry (2022)

 

Abstract

Three thiazole derivatives bearing thiophene and selenophene are synthesized and used as monomers for electropolymerization. The electropolymerization process is studied using cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM) techniques. Deep understanding is obtained regarding the pseudocapacitor performance of deposited polymer layers by subjecting the macroelectrode and ultramicroelectrode to CV and galvanostatic charging–discharging experiments in three kinds of electrolytes. Notably, the highest specific capacitance is observed in the derivative bearing selenopheno[3,4-d]thiazole and selenophene in a solution of tetrabutylammonium tetrafluoroborate. Furthermore, the electropolymerization rate is influenced by the kind of chalcogenophene and the CV scan rate. A spectroelectrochemistry experiment reveals the optical and electrochromic behavior of the deposited polymer layers. From these results, the pseudocapacitor performance of the deposited polymer layers is related to anion intercalation/deintercalation processes by faradaic reactions of oligomer chains. The EQCM experiments also reveal these processes during electropolymerization and anion intercalation/deintercalation into the deposited polymer layers. Finally, the approximate molecular weight of the solvated anion and the number of solvent molecules surrounding a solvated anion are analyzed using the EQCM data.

 

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