The main purpose of this work was to determine adsorption characteristics of fluoride, nitrate and sulfate ions on the AFN membrane. The sorption isotherms for , and ions on the AFN membrane were investigated in the range of 0.05–1 mol.L–1 at 298 K. The suitability of the Langmuir, Dubinin–Astakhov (D-A) and Redlich–Peterson adsorption models to the equilibrium data was investigated. The sorption parameters of the studied models were determined by non-linear regression and discussed. Equilibrium data obtained in this study were found to best fit the Langmuir isotherm. The ΔG° values deduced from the Langmuir isotherm suggest that the affinity order of the AFN membrane for the studied anions is: . In order to improve their selectivity towards monovalent ions, the AFN membrane was modified by adsorption of polyethyleneimine on its surface. Adsorption parameters values of the studied models were determined for the modified AFN membrane. The D-A model provides the best fit to the experimental points. In fact, removal of fluoride and nitrate ions by adsorption on the modified AFN membrane was more effective than the adsorption on the unmodified one. Desorption of fluoride from the modified AFN membrane by nitrate and sulfate ions was investigated.
A combined system of ion exchange (IX) and advanced biophysical treatment of a recirculating regenerant was tested for nitrate removal from groundwater with minimal brine discharge and chloride addition to the product water. Using well water containing 21.5 ± 1.4 mg NO3−-N/L, optimal IX operation was found at a service cycle of 500 bed volumes (BV). Product water nitrate concentrations (7.4 ± 1.4 mg/L as N) met regulations while minimizing both Cl− addition to the treated water (1.03 meq Cl− added per meq NO3−-N...
In this study, ozonation treatment of C.I. Reactive Black 5 (RB5) was investigated at various operating parameters. The results showed that the aqueous solution initially containing 200 mg/L RB5 was quickly decolorized at pH 8.0 with an ozone dose of 3.2 g/h. Reaction intermediates with m/z 281, 546, 201, 350, 286 and 222 were elucidated using liquid chromatography-mass spectrometry, while sulfate ion, nitrate ion and three carboxylic acids (i.e., oxalic acid, formic acid, and acetic acid) were identified by ion...
We introduce vacuum ultraviolet (VUV) photolysis at 172 nm as a more efficient process for bromate and chlorate removal than conventional ultraviolet (UV) photolysis at 254 nm. We discuss the effects of pH and coexisting salts on VUV photolysis. In experiments at various pH levels, the VUV photolysis performance decreased in the alkaline region for pH above 7. Furthermore, nitrate and inorganic carbon compromised the performance, probably owing to the generation of active oxidant species (such as hydroxyl...
Nitrate contamination of groundwater is an important issue in rural areas. In this study, an electrolytic method for the denitrification of groundwater was investigated in a laboratory reactor. We used an ion-exchange membrane, employing a titanium oxide anode and five kinds of cathode for the investigation. The nitrate removal efficiencies with Cu, Pb, Ti/Ir/Ru, Ti/Ir/Ta, and Zn cathodes were 30.0%, 59.9%, 73.8%, 23.3%, and 80.6%, respectively. A cation-selective membrane was employed to separate the electrode...
Nitrate is a naturally occurring substance in the environment and is commonly found in most water sources, it is usually only a cause for concern in areas where water supplies can be affected by farm runs offs and agriculture, its use as a fertiliser can cause increased levels in water supplies
The UK safe limit for nitrates in Drinking water is 50mg/l as described in the current advice on Nitrate from the DWI, The Drinking water institute.
There are a range of options to test water for nitrates with different...
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