A study on the sorption of NO₃⁻ and F⁻ on the carboxymethylated starch‐based hydrogels loaded with Fe²⁺ ions

Abstract

Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F 2 from water systems. The scheme was further applied for the removal of NO 3 2 also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe 21 ions to generate anchorage for the anions. Sorption of Fe 21 was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe 21 uptake was loaded with the Fe 21 ions under optimum conditions and used for the sorption of F 2 and NO 3 2 . High efficiency has been observed for F 2 , as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO 3 2 , which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes.

Effect of acid on morphology of calcite during acid enhanced defluoridation

“…Some recently used adsorbent for fluoride are laterite [20], waste residue from alum manufacturing plant [21], activated carbon prepared from Morringa Indica bark [22], carboxymethylated starch-based hydrogels loaded with Fe 2+ [23], alum-impregnated activated alumina [24], etc. However, due to high cost, low efficiency or production of huge amount of sludge containing fluoride they do not find practical field utility.…”

Novel Polycarboxylated Starch-Based Sorbents for Cu2+ Ions

“…22,23 Functionalized starch is effective in the removal of metal ions 1 and finds use in water purification technologies. [3][4][5][6][24][25][26][27][28][29] Removal of Cu 2+ has also been reported using functionalized starch having different types of active groups. [30][31][32] The oxidized starch having carboxylic groups is of interest due to the effective chelation and antiflocculation properties of the carboxylic groups.…”

“…Starch-based functional polymers have been used in water/environment management technologies. , Starch has been modified by derivatization, grafting, network formation, and other polymer analogous reactions. , The starch derivatives (polyelectrolytes) containing amide groups have been reported for the removal of heavy metal ions from their aqueous solutions . The effect of the derivative structure on the adsorption efficiency was reported to follow the order of carbamoylethylated starch > poly(acrylamide)−starch graft copolymer > starch carbamate.…”

“…Oxidation of starch with nitrogen oxides is a highly selective, rapid, clean, and efficient process . In this process oxidation at the primary hydroxyl groups is the predominant reaction. , Functionalized starch is effective in the removal of metal ions and finds use in water purification technologies. − ,− Removal of Cu 2+ has also been reported using functionalized starch having different types of active groups. − The oxidized starch having carboxylic groups is of interest due to the effective chelation and antiflocculation properties of the carboxylic groups …”

A Study of Nitrate Uptake from Aqueous Solutions Using Isotactic Polypropylene-based Anion Exchangers

“…reported the use of a magnetic anion exchanger for the selective removal of nitrate. The natural polymers-based functional hydrogels, those offer the advantages of cost effective being of renewable nature, have been used as supports for efficient removal of nitrate [15][16][17][18][19][20]. These also offer an ease of modification by the polymer analogous reactions.…”