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Zhu X, Yang Q, Li X, Zhong Y, Wu Y, Hou L, Wei J, Zhang W, Liu Y, Chen C, Wang D. Enhanced dewaterability of waste activated sludge with Fe(II)-activated hypochlorite treatment. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:27628-27638. [PMID: 30056538 DOI: 10.1007/s11356-018-2829-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/20/2018] [Indexed: 06/08/2023]
Abstract
A novel method was explored to improve the waste-activated sludge (WAS) dewaterability using Fe(II) combined with calcium hypochlorite, and the possible mechanisms were investigated simultaneously. Capillary suction time (CST), specific resistance to filtration (SRF) of sludge, and water content (WC) of dewatered sludge cake were selected as the factors to evaluate the sludge dewaterability. The maximum reduction of WC (30.76%) was achieved under the optimal conditions of Ca(ClO)2 0.04 g/g total suspended solids (TSS), FeSO4·7H2O 0.097 g/g TSS, and pH 7.3, while the reduction of CST and SRF reached 91.24 and 99.47%, respectively. Three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy of extracellular polymeric substances (EPSs) showed that sludge dewaterability was mainly related to the degradation of tryptophan and tyrosine protein-like substances in sludge EPS. Economic analysis suggested Fe(II) combined with calcium hypochlorite treatment had greater potential on enhancing WAS dewaterability compared with the traditional sludge treatment.
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Affiliation(s)
- Xiaofei Zhu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Qi Yang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China.
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
| | - Xiaoming Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China.
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
| | - Yu Zhong
- Key Laboratory of Water Pollution Control Technology, Hunan Research Academy of Environmental Sciences, Changsha, 410004, China
| | - You Wu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Lihua Hou
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Jing Wei
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Weixuan Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Yu Liu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Chongyu Chen
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Dongbo Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
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Hu Y, Xie G, Stanbury DM. Oxidations at Sulfur Centers by Aqueous Hypochlorous Acid and Hypochlorite: Cl + Versus O Atom Transfer. Inorg Chem 2017; 56:4047-4056. [PMID: 28290673 DOI: 10.1021/acs.inorgchem.6b03182] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Sulfur-containing compounds are known to be susceptible to oxidation by aqueous HOCl, but the factors affecting the rates of these reactions are not well-established. Here we report on the kinetics of oxidation of thiosulfate, thiourea, thioglycolate, (methylthio)acetate, tetrathionate, dithiodiglycolate, and dithiodipropionate at 25 °C and 0.4 M ionic strength. These reactions obey the general rate law -d[OCl-]/dt = (kOCl-[OCl-] + kHOCl[HOCl])[substrate] with some exceptions: tetrathionate and the two disulfides undergo rate-limiting hydrolysis at high pH, and dithiodiglycolate has an additional term in the rate law that is second order in [substrate]. The reactions of HOCl are believed to have a Cl+ transfer mechanism, and in the case of thiosulfate the rate of hydrolysis of the ClS2O3- intermediate was determined. In the case of thiourea evidence was obtained for thiourea monoxide as a long-lived product. It is shown that sulfite and species with terminal sulfur atoms have kHOCl values in the vicinity of 1 × 109 M-1 s-1, while SCN- and thioethers react somewhat more slowly; tetrathionate, trithionate, and disulfides react much more slowly. Comparison of the rate constants with those for oxidation of these sulfur substrates by H2O2 and [Pt(CN)4Cl2]2- shows that HOCl reacts a few orders of magnitude more rapidly than [Pt(CN)4Cl2]2- and ∼9 orders of magnitude more rapidly than H2O2. Many of the kHOCl values are leveled by the high electrophilicity of HOCl. It is proposed that the kOCl- values correspond to oxygen-atom transfer mechanisms, as supported by LFERS (linear free energy relationships) relating these rate constants to those for reactions of H2O2 and [Pt(CN)4Cl2]2-.
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Affiliation(s)
- Ying Hu
- College of Chemical Engineering, China University of Mining and Technology , Xuzhou 221116, People's Republic of China.,Dept. of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States
| | - Guangyuan Xie
- College of Chemical Engineering, China University of Mining and Technology , Xuzhou 221116, People's Republic of China
| | - David M Stanbury
- Dept. of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States
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Li G, Xia Y, Zhao Y, Li P, Zhang F, Qu P. Solid–Liquid Reaction Synthesis of High-Purity Potassium Hexathionate and Its Antibacterial Properties. Aust J Chem 2016. [DOI: 10.1071/ch15329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Hexathionate, an intermediate in the oxidation process of inorganic sulfur compounds, plays important roles in different fields of chemistry, chemical technology, and biology. To achieve innovative results in different fields related to polythionates, the use of hexathionate is crucial, however, it is not yet commercially available. Herein, we report a simple and convenient method to prepare high-purity potassium hexathionate. Hexathionic acid was easily synthesised through a solid–liquid reaction between sodium thiosulfate (solid) and disulfur dichloride. The potassium salt crude product was obtained by neutralising hexathionate acid with potassium hydroxide, and was purified successively using 0.1 M sulfuric acid and 0.5 M hydrochloric acid. A high product purity of 99.8 % (titrimetric analysis, 98.81 %) was obtained. The antibacterial activities of potassium hexathionate against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa) were determined by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) analyses and the cup diffusion method. Potassium hexathionate displayed more effective antibacterial activities against P. aeruginosa than S. aureus. The MICs against P. aeruginosa and S. aureus were 1.95 and 125 µg mL–1, respectively. The corresponding MBC value against P. aeruginosa was 1000 µg mL–1. Furthermore, the duration of the antimicrobial activity, determined by the cup diffusion, shows the potential of potassium hexathionate as a sustained antibacterial candidate. However, there is no bactericidal activity against S. aureus in the concentration range tested.
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