Influence of Film Stability and Aging of Plasma Polymerized Allylamine Coated Quartz Particles on Humic Acid Removal

Abstract

Plasma polymerized allylamine (ppAA) films have been successfully deposited on to the surface of quartz particles via a rotating barrel plasma reactor for humic acid removal. The films were deposited at a power of 25 W, allylamine flow rate of 4.4 sccm and polymerization times of 5 to 60 min. X-ray photoelectron spectroscopy was used to investigate the influence of short-term stirring in water and film age on surface chemistry. Stirring results in a reduction in the nitrogen concentration, which was greatest for shorter polymerization times. Film aging of up to 52 weeks appeared to result in a reduction in the concentration of C-N species. The influence of batch, recycling, and film age on humic acid removal was investigated. Humic acid removal appeared to be reproducible across three separate batches for polymerization times of 20 min or more, which was attributed to film thickness. Recycling of the ppAA films was most successful at pH 11 for up to 4 humic acid removal/regeneration cycles. Successful regeneration at pH 11 was attributed to electrostatic repulsion of the adsorbed humic acid molecules. Decreasing the pH of the regeneration solution reduced the number of successful regeneration cycles due to greater retention of adsorbed humic acid via electrostatic attraction. Film age appears to have minimal effect on humic acid removal where freshly deposited and 52-week-old films removed similar masses of humic acid. Successful production and development of ppAA coated quartz particles has resulted in a functional material that can be incorporated into a water treatment system to improve water quality.

Optimizing Humic Acid Removal by Modifying the Surface Chemistry of Plasma Polymerized Allylamine Coated Particles

“…Such behavior has previously been observed for ppAA coated quartz particles. [29] For immersion times of 10 and 30 min, a relationship between plasma power and reduction in atomic nitrogen concentration was observed. The reductions in the atomic nitrogen concentrations were generally less for plasma powers greater than 25 W, which indicates ppAA films deposited at higher powers are more stable in aqueous solution.…”

“…[19] Our previous research has demonstrated particle modification with a number of monomers using a rotating plasma reactor. [20][21][22][23][24][25][26][27][28][29] This research investigates varying the plasma power, allylamine flow, and polymerization time to optimize humic acid removal. The effect of these parameters on surface chemistry and stability in solution was analyzed via X-ray photoelectron spectroscopy.…”

Plasma surface modification of materials and their entrapment of water contaminant: A review

“…Silica particles are widely used as the substrates of various materials due to a lot of advantages, such as low‐cost, commercially available, and mechanically stable. And recently, Majewski et al have made great contributions to modifying silica particles by using plasma‐assisted approach, which has been applied in the entrapment of various contaminants in wastewater …”

“…This modified silica particles shows great adsorption capacity for HA removal via electrostatic attraction and hydrogen bonding. Thus, the allylamine coated quartz particles by plasma technique could be extended by the demonstration of reproducible HA removal, successful regeneration, and the minimal influence of film age, which makes it enable reuse and storage in real applications . Majewski also used 1,7‐Octadiene (OD) to modify silica particles by using plasma polymerization for the removal of petroleum hydrocarbon, shown in Figure .…”

Influence of Particle Mass and Flow Rate on Plasma Polymerized Allylamine Coated Quartz Particles for Humic Acid Removal

“…Plasma treatment with ammonia can however also be used to produce amine terminated surfaces . Plasma polymerized allylamine has been used to improve the hydrophilicity of water treatment membranes, but has only recently been investigated for contaminant removal . The chemistry and structure of allylamine plasma polymerized films can be manipulated by varying the input power and allylamine flow rate.…”