Surfactant-Free Hydrothermal Synthesis of Mesoporous Niobia Samples and Their Photoinduced Decomposition of Terephthalic Acid (TPA)

Acetalization of acetone with glycerol catalyzed by niobium-aluminum mixed oxides synthesized by a sol–gel process

“…The broad band in the range of 550-630 cm −1 has been assigned to Nb-O stretching whereas the shoulder-like band at around 900 cm −1 has been assigned to either Nb = O or Nb-O-Nb stretching modes in polymerized NbO x species [40], respectively. The latter signal is more defined in 1Nb:0.3Al, 1Nb:0.1Al, 1Nb:0.05Al and Nb 2 O 5 , and is associated to the remarkable concentration of highly distorted niobium oxide species containing Nb = O bonds in the crystalline phase [30,41], in agreement with the XRD data presented in Fig. 1.…”

Porous p-NiO/n-Nb2O5 nanocomposites prepared by an EISA route with enhanced photocatalytic activity in simultaneous Cr(VI) reduction and methyl orange decolorization under visible light irradiation

“…and MO, the adsorbed percentages and subsequent photoreaction's rates at low pH were larger than those at high pH. As it is known and has been mentioned in our previous publications [9,10,17,35], the point of zero charge (PZC) pH (pH pzc ) is the pH value at which the net electric charge of a molecule is zero and this pH value greatly influences the adsorption of pollutant substrates and intermediates on the surface of a photocatalyst during a photoreaction. Therefore, in order to find out optimal pH for the simultaneous photoreduction of Cr(VI) and decolorization of MO, the pH pzc of NiNb0.4 catalyst was measured by the so-called zeta-potential method [58].…”

“…Among the many semiconductor materials, applications of Nb 2 O 5 as a well-known n-type material have become widely prevalent [35] due to their unique physical properties such as a high refractive index, a wide band gap (3.1-3.5 eV), good chemical and thermal stability and good photocatalytic characteristics. NiO as a p-type semiconductor [36,37], is considered to be a suitable semiconductor to be coupled with Nb 2 O 5 due to its appropriate valence band position, high p-type concentration, higher hole mobility, cost effectiveness and similar photocatalytic mechanism as compared to Nb 2 O 5 [38].…”

Effect of Pyrolysis Temperature on Copper Aqueous Removal Capability of Biochar Derived from the Kelp Macrocystis pyrifera

“…The electric conductivity (EC) (Orion Star A212) and pH (pH/ORP meter, Hanna Instruments) of the BCs were measured in 1:20 dilute suspensions of biochar sample/DI water, with an equilibrium time of 1.5 h, according to the Standardized Product Definition and Product Testing Guidelines for Biochar that is Used in Soil (IBI-STD-2.1, 2015; http://www.biochar-international.org/ characterizationstandard, accessed on February 2021). Finally, the point of zero charge (pH pzc ), at which the number of negative sites is equivalent to the number of positive sites (total external and internal charge of the particles is zero), was obtained according to the process described in [24].…”