RT Journal Article ID 640270214d5e1a93 A1 Treshchalov, Aleksei A1 Tsarenko, Sergey A1 Avarmaa, Tea A1 Saar, Rando A1 Lohmus, Ants A1 Vanetsev, Alexander A1 Sildos, Ilmo T1 He/H2 Pulsed-Discharge Plasma as a Tool for Synthesis of Surfactant-Free Colloidal Silver Nanoparticles in Water JF Plasma Medicine JO PMED YR 2016 FD 2016-09-30 VO 6 IS 1 SP 85 OP 100 K1 alkalization K1 bipolar discharge K1 denitrification K1 electrostatic stabilization K1 helium K1 hydrogen K1 nanoparticle K1 plasma K1 plasma-liquid interface K1 silver AB In this study we investigated the interaction of atmospheric-pressure helium (He) and He/H2 pulsed-discharge plasma with different water solutions. We developed a synthetic path to obtain fairly uniform, small (~2 nm), surfactant-free silver (Ag) nanoparticles (NPs) with the treatment of an AgNO3 solution with He/H2 bipolar pulsed discharge. The colloidal solutions containing Ag NPs are stable for months and do not show any agglomeration (the measured zeta potential is 41 mV at pH ~8). The adsorption of negatively charged hydroxide (OH) ions on the surface of Ag NPs could be responsible for the electrostatic stabilization. The treatment of the air-saturated water by pure He plasma with a negative polarity leads to the creation of HNO3 and hydrogen peroxide (H2O2) as stable species. Contrary to the acidification of the solution by He plasma treatment, He/H2 discharge with negative and, in particular, with bipolar pulses produces only traces of HNO3 and no H2O2. We demonstrate here that He/H2 discharge with bipolar pulses is remarkably efficient in near-complete nitrate decomposition and slight alkalization of dilute HN03 and KNO3 solutions. PB Begell House LK https://www.dl.begellhouse.com/journals/5a5b4a3d419387fb,2cf1e1a94009b3e1,640270214d5e1a93.html