Photoinduced reactivity of titanium dioxide

https://opus.lib.uts.edu.au/bitstream/10453/33344/4/A%20review%20on%20the%20occurrence%20of%20micropollutants%20in%20the%20aquatic%20environment%20and%20their%20fate%20and%20removal%20during%20wastewater%20treatment.pdf

A review on the occurrence of micropollutants in the aquatic environment and their fate and removal during wastewater treatment

Biosorbents for heavy metals removal and their future

Occurrence, behavior and effects of nanoparticles in the environment.

Combination of Advanced Oxidation Processes and biological treatments for wastewater decontamination—A review

Anaerobic ammonia oxidation (anammox) is an environmentally friendly, cost-effective, and biological method for nitrogen treatment from aqueous solutions. However, slow growth rate, negative effects of high concentration of nitrite, ammonia and other pollutants (such as metals) on anammox activity are the main drawbacks of using anammox. Thus, in this study, anammox was attached on chitosan to improve anammox performance. Two reactors comprising chitosan and anammox bacteria (first reactor, chitosan/anammox) and solely anammox (second reactor, control) were run for 73 d. The nitrogen loading rate (NLR) varied from 2 to 14 (gN/L/d), while the nitrogen concentration varied from 80 to 700 mg/L. The chitosan/anammox reactor showed a better performance than the sole anammox (control), with respective maximum abatement values of ammonia (NH4+), nitrite (NO2-), and total nitrogen (TN) of 90.8%, 83.5%, and 81.7% on days 20–25 under a NLR of 8–10 kgTN/(m3 d). Response surface methodology (RSM) was employed to optimize the performance of both reactors, and a reasonable R2 value showed that the RSM well optimized the performance of the reactors. After finding the optimum performance conditions for both reactors, Fe and Cu (0.5–7.0 mg/L) were added to the influent to monitor the effects of metals on the performance of both reactors. The performance of both reactors decreased to 0% following the addition of 7.0 (first reactor) and 6.5 (second reactor) mg/L Cu and Fe, respectively. This indicated that chitosan not only enhanced nitrogen removal by anammox but also improved the resistance of anammox to metals.

Performance optimization of a chitosan/anammox reactor in nitrogen removal from synthetic wastewater

Chloride-binding capacity of cement-GGBFS-nanosilica composites under seawater chloride-rich environment

Water pollution is considered a serious threat to human life. An advanced oxidation process in the presence of semiconductor photocatalysts is a popular method for the effective decomposition of organic pollutants from wastewater. TiO2 nanoparticles are widely used as photocatalysts due to their low cost, chemical stability, environmental compatibility and significant efficiency. The aim of this study is to review the photocatalytic processes and their mechanism, reaction kinetics, optical and electrical properties of semiconductors and unique characteristics of titanium as the most widely used photocatalyst; and to compare the photocatalytic activity between different titania phases (anatase, rutile, and brookite) and between colorful and white TiO2 nanoparticles. Photocatalytic processes are based on the creation of electron–hole pairs. Therefore, increasing stability and separation of charge carriers could improve the photocatalytic activity. The synthesis method has a significant effect on the intensity of photocatalytic activity. The increase in the density of surface hydroxyls as well as the significant mobility of the electron–hole pairs in the anatase phase increases its photocatalytic activity compared to other phases. Electronic and structural changes lead to the synthesis of colored titania with different photocatalytic properties. Among colored titania materials, black TiO2 showed promising photocatalytic activity due to the formation of surface defects including oxygen vacancies, increasing the interaction with the light irradiation and the lifetime of photogenerated electron–hole pairs. Among non-metal elements, nitrogen doping could be effectively used to drive visible light-activated TiO2.

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Investigation of Advanced Oxidation Process in the Presence of TiO2 Semiconductor as Photocatalyst: Property, Principle, Kinetic Analysis, and Photocatalytic Activity

Persistent organic pollutants(POPs) such as organochlorine pesticides are of global concern due to their widespread occurrence and persistence. This paper reports recent research studying the distribution and fate of organochlorine pesticides in the Jiulong River, the Minjiang River and the Pearl River estuaries in Southeast China. Eighteen organochlorine pesticides were extracted from water, pore water and sediment samples, followed by analysis by GC-ECD. The results showed that the contamination levels were similar in these three estuaries.The levels of the total organochlorine pesticides in porewater were significantly higher than those in surface water, due to the high affinity of these hydrophobic compounds for sediment phase. Among the hexachlorocyclohexane (HCH) compounds, β-HCH was found to be the most important isomer. The analysis of 1, 1,1-trichloro-2,2-bis-chlorophenyl-ethane(DDT) and its metabolites showed that 1, 1-dichloro-2[o-chlorophenyl]-2[p-chlorophenyl]-ethylene (DDE) was dominant in the group.Koywords Organochlorine insecticides, DDT, Lindane, Jiulong River Estuary, Minjiang River Estuary, Pearl River Estuary, Water, Sediment

Contamination by organochlorine pesticides in the estuaries of southeast China

Elevated polycyclic aromatic hydrocarbon (PAH) concentrations were determined in different Chinese coals, with the highest concentrations in bituminous coals. Phenanthrene (Phen) was chosen as the probe compound for PAHs to study the sorption behavior of coal. No native Phen was detected in desorption experiments indicating irreversible sorption–desorption behavior of PAHs in raw coal samples. Sorption mechanism was further studied under varying conditions of pH value and ionic strength. Different ranks of coal showed different sorption behavior under acidic, neutral, and alkaline conditions. Batch experiments were further processed for the selected coals at pH values from 3 to 11 at a constant aqueous concentration. Sorption capacities of all coals decreased with increased pH except for YJ coal. Furthermore, although DOC-associated Phen mass contributed little to the total Phen mass under different pH values, the significant negative correlations between M
 DOC and log K
 OC values were observed for all coal samples, indicating a significant role played by DOC in the coal sorption. In addition, sorption experiments under varying ionic strength showed that the ionic strength influence was more obvious in sorption isotherms for higher rank coals with increasing ionic strength, and this effect was most significant when ionic strength increased from 0 to 0.15 M, especially at relatively low aqueous concentrations.

John L. Zhou

Papers

Performance optimization of a chitosan/anammox reactor in nitrogen removal from synthetic wastewater

Chloride-binding capacity of cement-GGBFS-nanosilica composites under seawater chloride-rich environment

Investigation of Advanced Oxidation Process in the Presence of TiO2 Semiconductor as Photocatalyst: Property, Principle, Kinetic Analysis, and Photocatalytic Activity

Contamination by organochlorine pesticides in the estuaries of southeast China

Polycyclic aromatic hydrocarbons (PAHs) in Chinese coal: occurrence and sorption mechanism