A new spectrophotometric method for determination of residual polydiallyldimethylammonium chloride flocculant in treated water based on a diazotization-coupled ion pair

Abstract

Polydiallyldimethylammonium chloride (polyDADMAC) is a water-soluble cationic polyelectrolyte used for water treatment. Its residues in treated water are contaminants as they react with chlorine to produce a carcinogenic compound. Commonly-used techniques for quantification of the polycation, such as colloidal and potentiometric titration as well as 1 H NMR, have poor sensitivity and detection limits. This paper describes a more sensitive UV spectrophotometric method for quantitative determination of residual polyDADMAC in treated water, through formation of an ion pair with (4-hydroxy-1-napthylazo) benzene-sulphonic acid (dye). The ion pair, which is a colloidal solid material, was characterised by FTIR, 13 C NMR and 1 H NMR techniques. The colloid materials formed with different concentrations of polyDADMAC were dissolved in either N,N-dimethylformamide or 1,4-dioxane, followed by determination with UV spectrophotometry. The wavelength of maximum absorption (λ max ) was found to be dependent on the solvent used, with 1,4-dioxane showing a better linear range of 0.1-1.8 mg•ℓ -1 polyDADMAC. Varying the pH of the solutions had no significant effect on λ max .

High Na‐ion conductivity and mechanical integrity of anion‐exchanged polymeric hydrogel electrolytes for flexible sodium ion hybrid energy storage

“…The exchange reaction between Cl − and ClO is attributed to the interaction of ClO 4 − with CH 3 at the position 7. 35 Moreover, the x-DDA-Dex and ex-DDA-Dex hydrogel films exhibit no changes in the two chemical shifts at 71.3 and 38.5 ppm. On the other hand, 30.1 and 26.7 ppm of x-DDA-Dex hydrogel at the position 4 and 5 were moved into 27.9 and 26.6 ppm of ex-DDA-Dex hydrogel at the position 9 and 10 after the anion exchange from Cl − to ClO 4 − .…”

Gold nanoparticles for the quantification of very low levels of poly-diallyldimethylammonium chloride in river water

“…16 From UV-vis based methods, various authors have reported LOD values between 0.5 mg L À1 and 1.0 mg L À1 respectively. 1,2,17,18 Our current method is a significant improvement over previous methods with a LOD of 0.54 mg L À1 .…”

“…Stability problems can be encountered with colloidal titration techniques such as the colour change reverting back to the original starting colour or the loss of colour on standing. 17,18 To determine the resistance of the method with respect to time, a 30 mg L À1 poly-DADMAC solution was prepared, mixed with Au-NPs, and the UV-vis spectrum was recorded every 5 minutes for 50 minutes. This experiment was done in triplicate.…”

“…The method had a linear range of 0.1-1.8 mg L À1 and a detection limit of 0.07 mg L À1 . 18 An alternative technique was developed by Eldridge et al, where the authors used pre-and post-uorescent tagging of poly-DADMAC to determine low levels (detection limits of 10-40 mg L À1 ) of the polymer in various water samples. 4 However, all these methods are complicated or require several pre-treatment steps, can be expensive and very time consuming, and may not be suitable for routine analysis of poly-DADMAC in river water.…”

Removing free-floating oil from water using cationic polymers/surfactant-modified silica

“…The adsorption of PDM on silica particles was studied by spectrophotometry based on a diazotization-coupled ion pair (Mwangi et al 2012). The absorbance of standard solutions of PDM ion pair in the range of 0.1-25.0 mg/l was measured at the wavelength of 230 nm for setting up the calibration curve.…”