Settleable engineered titanium dioxide nanomaterials for the removal of natural organic matter from drinking water

Abstract

Four linear engineered TiO 2 nanomaterials (LENs) were synthesized and evaluated in terms of settlability and their ability to remove natural organic matter (NOM) from river water. The size, surface characteristics, and crystallinity of the LENs were manipulated by varying the temperatures used during the synthesis procedure. All four LENs settled out of purified water more effectively than standard Degussa Evonik Aeroxide P25 nanoparticles. The settling behaviour of the nanomaterials was impacted by surface charge effects and interactions with NOM and ionic species in the river water matrix. The reduction of two disinfection byproduct precursor surrogate parameters, DOC and UV254, by the LENs via adsorption (no irradiation) and photocatalytic degradation under UVA LED irradiation was compared to that by P25 nanoparticles. After 60 minutes of irradiation DOC removal by the LENs ranged from 20 to 50% and UV254 reduction ranged from 65 to 90%. Two of the most promising LENs were reused multiple times and although both materials experienced decreases in treatment efficacy over successive reuse cycles, the reusability of both LENs was equal to or superior to that of P25 nanoparticles. The electrical energy per order required to remove DOC and UV254 from the water ranged from 8 to 36 times higher than that required for UV/H 2 O 2 treatment but comparable to results reported by other researchers using UV/TiO 2 for NOM removal. A subset of the nanomaterials evaluated in this study may prove to be a viable alternative to standard TiO2 nanoparticles for the removal of DBP precursors from drinking water, but the characteristics of the water matrix have important effects on settling efficiency and will require site-specific evaluation.

Carbonate Adsorption to Ferrihydrite: Competitive Interaction with Phosphate for Use in Soil Systems

“…2−6 Moreover, recent developments in nanotechnology have shown promising results for the application of engineered FeNPs in a series of environmental and industrial cleanup applications, such as drinking and wastewater treatment. 7−9…”

“…The adsorption of ions to the natural Fe-(hydr)­oxides of soils is a key process that regulates the bioavailability, toxicity, and mobility of specific nutrients and contaminants in the environment . Particularly, understanding the interaction between Fe-(hydr)­oxide nanoparticles (FeNPs) and oxyanions such as phosphate (PO 4 3– ), sulfate (SO 4 2– ), silicate (SiO 4 4– ), and arsenate (AsO 4 3– ) is of great relevance as its behavior varies under a wide range of environmental conditions. − Moreover, recent developments in nanotechnology have shown promising results for the application of engineered FeNPs in a series of environmental and industrial cleanup applications, such as drinking and wastewater treatment. − …”

Towards synergistic combination of biochar/ultrasonic persulfate enhancing removal of natural humic acids from water

“…Azar Fattahi et al found that the energy required for UV 254 removal of the system of LED with continuous irradiation of 405 nm, combined with P25 was 539.84 kW h/m 3 , which only showed little NOM removal rate [62]. Gora et al used TiO 2 nanobelts calcined at different temperatures and UVA-LED to degrade DOC in Otonabee River and Ottawa River water, whose maximum required energy reached 1085 kWh/m 3 [63,64]. Since the biochar/persulfate/ultrasonic system could achieve 90% removal rate for HAs within 60 min, the reaction time can be shortened according to the actual situation in order to reduce energy loss.…”

Photocatalytic Degradation of Microcystins by TiO2 Using UV-LED Controlled Periodic Illumination

“…E EO is the energy in kWh needed to decrease the microcystin or TPA concentration by one order of magnitude in a liter of water. E EO was calculated by the following equations [40,41]:…”