The effect of γ-FeOOH on enhancing arsenic adsorption from groundwater with DMAPAAQ + FeOOH gel composite

Abstract

Arsenic contamination of groundwater is a serious concern worldwide. The research gaps in removing arsenic are selectivity, regeneration and effective removal rate at neutral pH levels. In this study, we discussed the reasons of the high arsenic adsorption from groundwater of our previously developed adsorbent, a cationic polymer gel, N,N -dimethylamino propylacrylamide, methyl chloride quaternary (DMAPAAQ), loaded with iron hydroxide. We used a transmission electron microscope (TEM) and thermogravimetric analyser (TGA) to detect the iron contents in the gel and ensure its maximum impregnation. We found that the gel contains 62.05% FeOOH components. In addition, we used the Mössbauer spectroscopy to examine the type of impregnated iron in the gel composite and found that it was γ-FeOOH. Finally, we used Fourier transform infrared spectroscopy (FTIR) to examine the surface functional groups present in the gel and the differences in those groups before and after iron impregnation. Similarly, we also investigated the differences of the surface functional groups in the gel, before and after the adsorption of both forms of arsenic. To summarize, this study described the characteristics of the gel composite, which is selective in adsorption and cost effective, however further applications should be investigated.

Simultaneous Removal of Arsenic and Manganese from Synthetic Aqueous Solutions Using Polymer Gel Composites

“…To perform the Mn-adsorption experiment, 20 mg of dried gel composite (γ-FeOOH, DMAPAAQ, DMAPAAQ + FeOOH, DMAA, activated charcoal, silica gel, and DMAA + FeOOH) was added to 40 mL of Mn or As solution in a small beaker and stirred at 200 rpm at 20 • C for 24 h. We conducted our experiments with solutions of higher Mn concentrations to evaluate the maximum effectiveness of the adsorbents at the removal of Mn. The detailed compositions of DMAPAAQ, DMAPAAQ + FeOOH, DMAA and DMAA + FeOOH are described in our previous studies [11][12][13]. As activated charcoal and silica gel are effective adsorbents, we used them to examine their adsorptive effectiveness and compared them with our results.…”

“…The polymer gels DMAPAAQ and DMAPAAQ + FeOOH were prepared by the free-radical polymerisation method described in our previous studies [11][12][13] and also in Tables S2 and S3. The amounts of the crosslinker, initiator, and accelerator were identical in the compositions of DMAPAAQ, DMAPAAQ + FeOOH, and DMAA + FeOOH.…”

“…The amounts of the crosslinker, initiator, and accelerator were identical in the compositions of DMAPAAQ, DMAPAAQ + FeOOH, and DMAA + FeOOH. For the composites DMAPAAQ + FeOOH and DMAA + FeOOH, FeCl 3 and NaOH were added to impregnate the iron components in the polymer gel structure [11][12][13]. The reason for adding NaOH was that NaOH reacted with FeCl 3 during the polymerisation.…”

“…Previously, we reported the effective removal of As from groundwater using our novel adsorbent, N,N'-Dimethylaminopropyl acrylamide, methyl chloride quaternary (DMA-PAAQ), loaded with γ-FeOOH (DMAPAAQ + FeOOH) [11][12][13]. It has been reported that γ-FeOOH effectively removes Mn [14].…”

“…In this study, we investigated the adsorptive removal of Mn using our previouslydeveloped gel, DMAPAAQ + FeOOH [11][12][13]. Additionally, we compared the Mn removal efficiency of DMAPAAQ + FeOOH gel to that of the non-ionic gel, N,N'-Dimethylacrylamide (DMAA) and non-ionic gel composite (DMAA + FeOOH).…”