Stability Of Agents Research Articles

Facile fabrication of Anti-biofouling polyaniline ultrafiltration membrane by green citric acid doping process

• Antibiofouling polyaniline UF membrane was prepared by citric acid doping. • Doping made the surface antiadhesive via enhanced hydrophilicity/electroneutrality. • Fouling on the doped membrane was easily removed, surface was free of bacteria. • The doped membrane was stable for up to 5-month storage in NaCl. • The protocol is facile, scalable for large-scale production and doping is green. This study aimed to enhance the anti-biofouling property of the polyaniline (PANI) based ultrafiltration (UF) membrane by utilizing its self-acid doping ability. A naturally derived biodegradable agent, citric acid, was doped to the membrane by filtering at 1 bar. Acid doping increased the hydrophilicity, made the surface nearly electroneutral, and imparted biocidal characteristics to the membrane. Biofouling was simulated by filtering a suspension of E.coli and S.aureus through the membranes. Most fouling on the doped membrane was reversible and easily removed by simple washing, leading to a high flux recovery ratio. The SEM images taken after filtration and washing steps showed that the modified membrane surface was free of bacteria while many bacteria accumulated on the pristine membrane surface. The doped membrane was stored in 1 M NaCl solution for up to five months. A tiny amount of citric acid was lost from the membrane, and at the end of storage, the flux, rejection, and antibacterial activity values did not change, demonstrating the antibacterial agent's stability. The protocol proposed in this study is fast, simple, facile, and easily scalable for large-scale production. Using a green antibacterial agent and its loading with a one-step process without consuming chemicals or functionalizing the support makes the proposed method environmentally friendly.

Research on the influence of wollastonite fibers on the stability of foam extinguishment agent and its effect on the extinguishing efficiency of pool fire

SummaryAqueous film‐forming foam (AFFF) is a frequently used foam extinguishment agent for oil fires, but the foam stability of AFFF is not perfect, which results in poor fire extinguishing performance. In order to improve the foam stability of AFFF, wollastonite fibers were explored to increase the performance of foam extinguishment agent. The influences of wollastonite fibers' concentration on foam extinguishment agent's stability are studied. When the concentration of wollastonite fibers is 30.00 g/100 mL, the drainage time is prolonged, which is the best among all the formulas. Moreover, the fire resistance and fire‐fighting performances are increased significantly due to the incorporation of wollastonite fibers. In order to reveal the effect of wollastonite fibers on the stability of foam extinguishment agent, the structure of the foam and the diameter of the bubbles are investigated. The results show that the complexity and compactness of foam layer's structure are very important for foam stability, and the fire‐extinguishing performance is improved due to the introduction of wollastonite fibers.