scholarly journals Long-term effect of metal oxide nanoparticles on activated sludge

2016 ◽  
Vol 75 (2) ◽  
pp. 462-473 ◽  
Author(s):  
Baranidharan Sundaram ◽  
Arun Kumar

This study evaluated the influence of metal oxide nanoparticles (NPs) (Ag2O, TiO2) and their mixture on activated sludge for 180 days. When tested, a mixture of NPs at 1 and 10 mg/L had greater impact than individual NPs, in which maximum reduction in chemical oxygen demand (COD) elimination (76.3%) was observed after 150 days for 1 mg/L (500 mg/L COD concentration) and after 180 days (70.2%) for 10 mg/L (250 mg/L COD concentration). TiO2 had higher inhibition on COD reduction than Ag2O NPs at 1 and 10 mg/L. An antagonistic effect was observed in which the combination of individual NPs had a greater effect than a mixture of NPs. Reduction in COD elimination was found to be dependent on NP type and concentration (p < 0.05). Further, metal ion concentration was higher in sludge than supernatant irrespective of NPs, while microscopic analysis showed the presence of NPs inside activated sludge. Among NPs tested, the concentration of Ti4+ ion was greater in sludge than in the Ag+ ion, thus indicating that TiO2 has a greater affinity than Ag2O NPs. All three factors (NP type, NP concentration, organic concentration) play a significant role in imparting COD removal (p < 0.05). Future studies are required to quantify NP concentration to minimize NP effect on plant performance.

2013 ◽  
Vol 246 ◽  
pp. 125-136 ◽  
Author(s):  
K. Yogesh Kumar ◽  
H.B. Muralidhara ◽  
Y. Arthoba Nayaka ◽  
J. Balasubramanyam ◽  
H. Hanumanthappa

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3446
Author(s):  
Mohammed Zahedul Islam Nizami ◽  
Veena W. Xu ◽  
Iris X. Yin ◽  
Ollie Y. Yu ◽  
Chun-Hung Chu

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative mechanisms. Silver, zinc, titanium, copper, and magnesium ions have been used to develop metal and metal oxide nanoparticles. In addition, fluoride has been used to functionalise the metal and metal oxide nanoparticles. The fluoride-functionalised nanoparticles show fluoride-releasing properties that enhance apatite formation, promote remineralisation, and inhibit demineralisation of enamel and dentine. The particles’ nanoscopic size increases their surface-to-volume ratio and bioavailability. The increased surface area facilitates their mechanical bond with tooth tissue. Therefore, metal and metal oxide nanoparticles have been incorporated in dental materials to strengthen the mechanical properties of the materials and to prevent caries development. Another advantage of metal and metal oxide nanoparticles is their easily scalable production. The aim of this study is to provide an overview of the use of metal and metal oxide nanoparticles in caries prevention. The study reviews their effects on dental materials regarding antibacterial, remineralising, aesthetic, and mechanical properties.


Author(s):  
Sagadevan Suresh ◽  
Selvaraj Vennila ◽  
J. Anita Lett ◽  
Is Fatimah ◽  
Faruq Mohammad ◽  
...  

2021 ◽  
Vol 23 (8) ◽  
Author(s):  
Eliecer Peláez Sifonte ◽  
Fidel Antonio Castro-Smirnov ◽  
Argenis Adrian Soutelo Jimenez ◽  
Héctor Raúl González Diez ◽  
Fernando Guzmán Martínez

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