126
E. Emekdar and U. K. ¸
Sahin
Salt amount affects removal amount adversely such that Al ion presence in solution
has the worst removal performance [83].
Rahimdokht et al. synthesized a photocatalyst as TiO 2 /gum tragacanth hydrogel
for the methylene blue dyestuff removal from polluted solutions. The hydrogel was
produced by sonication of TiO 2 nanoparticles into gum tragacanth, and they added
glutaraldehyde as a cross-linking agent. They yielded maximum efficiency as 88.86%
with a pH of 9.02 a 124.34 min removal time [84].
Patel and Patel assert that their Cationic Poly [acrylamide/N-vinyl pyrrolidone/N,N-diallylpyrrolidinium bromide] [AAm/NVP/DAPB] hydrogels are
produced by free-radical solution polymerization with a cross-linker (N,N-methylene
bisacrylamide), initiator (2.2
-azobis (2-methylpropionamidine) dihydrochloride).
They used the hydrogels for removal of acid dyestuffs as Acid Yellow, Orange-II and
Reactive Golden Yellow. The best swelling was observed at YH5 with higher DAPB
amount, and dyestuff removing performance is seen as Acid Yellow < Orange-II <
Reactive Golden Yellow [85].
Dey et al. studied on semi-IPN and ester-based hydrogels production for wastewater refining treatments as an adsorbent. They produced their comonomer cross-linker
that was poly(ethylene glycol) di-itaconate by functionalizing poly(ethylene glycol)
(PEG 1500) with itaconic acid using melt esterification. Then, copolymerization
was done by using acrylamide and methylene bisacrylamide. For storage modulus,
dyestuff adsorption ability, and the anti-fungal, better results were yielded with esterbased gel than semi-IPN-type gels. Regardless of medium pH, swelling of hydrogel
decreased when the PEG amount was increased at semi-IPN gels; thus, dyestuff
adsorption decreased [86].
5.6 Comparison of All Adsorbent Materials
Clay is easily findable because its source is very high in nature, and it is ready to adsorb
thanks to high surface area, but it is very good to modify and produce a composite
with many polymer sources. Cellulose and chitosan derivatives are a good example
of composite production, especially with clay. They have also very wide sources, but
cellulose derivatives have more sources than chitosan derivatives in nature. Chitosan
is more likely to form cationic adsorbents, while cellulose derivative is close to
slightly anionic characteristics. For further usages of cellulose derivate-based adsorbents, usage conditions, especially temperature, are very important because they
are easily flammable, while chitosan derivatives provide flame-retardancy effect.
Chitosan and cellulose derivatives need attention for solubility, and they must be
turned into suitable forms. Also, chitosan has some viscosity problems because of
forming a gel-like solution even with water; thus, it needs extra control in processes.
However, it has a very valuable advantage as an antibacterial behavior for further
reuse applications of an adsorbent. Biochars are also natural sources, but it needs
extra processes to turn them into suitable forms of adsorbent materials and activation
of the adsorbent. These processes must need attention not to lose the quality of the
E. Emekdar and U. K. ¸
Sahin
Salt amount affects removal amount adversely such that Al ion presence in solution
has the worst removal performance [83].
Rahimdokht et al. synthesized a photocatalyst as TiO 2 /gum tragacanth hydrogel
for the methylene blue dyestuff removal from polluted solutions. The hydrogel was
produced by sonication of TiO 2 nanoparticles into gum tragacanth, and they added
glutaraldehyde as a cross-linking agent. They yielded maximum efficiency as 88.86%
with a pH of 9.02 a 124.34 min removal time [84].
Patel and Patel assert that their Cationic Poly [acrylamide/N-vinyl pyrrolidone/N,N-diallylpyrrolidinium bromide] [AAm/NVP/DAPB] hydrogels are
produced by free-radical solution polymerization with a cross-linker (N,N-methylene
bisacrylamide), initiator (2.2
-azobis (2-methylpropionamidine) dihydrochloride).
They used the hydrogels for removal of acid dyestuffs as Acid Yellow, Orange-II and
Reactive Golden Yellow. The best swelling was observed at YH5 with higher DAPB
amount, and dyestuff removing performance is seen as Acid Yellow < Orange-II <
Reactive Golden Yellow [85].
Dey et al. studied on semi-IPN and ester-based hydrogels production for wastewater refining treatments as an adsorbent. They produced their comonomer cross-linker
that was poly(ethylene glycol) di-itaconate by functionalizing poly(ethylene glycol)
(PEG 1500) with itaconic acid using melt esterification. Then, copolymerization
was done by using acrylamide and methylene bisacrylamide. For storage modulus,
dyestuff adsorption ability, and the anti-fungal, better results were yielded with esterbased gel than semi-IPN-type gels. Regardless of medium pH, swelling of hydrogel
decreased when the PEG amount was increased at semi-IPN gels; thus, dyestuff
adsorption decreased [86].
5.6 Comparison of All Adsorbent Materials
Clay is easily findable because its source is very high in nature, and it is ready to adsorb
thanks to high surface area, but it is very good to modify and produce a composite
with many polymer sources. Cellulose and chitosan derivatives are a good example
of composite production, especially with clay. They have also very wide sources, but
cellulose derivatives have more sources than chitosan derivatives in nature. Chitosan
is more likely to form cationic adsorbents, while cellulose derivative is close to
slightly anionic characteristics. For further usages of cellulose derivate-based adsorbents, usage conditions, especially temperature, are very important because they
are easily flammable, while chitosan derivatives provide flame-retardancy effect.
Chitosan and cellulose derivatives need attention for solubility, and they must be
turned into suitable forms. Also, chitosan has some viscosity problems because of
forming a gel-like solution even with water; thus, it needs extra control in processes.
However, it has a very valuable advantage as an antibacterial behavior for further
reuse applications of an adsorbent. Biochars are also natural sources, but it needs
extra processes to turn them into suitable forms of adsorbent materials and activation
of the adsorbent. These processes must need attention not to lose the quality of the