Human industrial, agricultural and mining activities are the reason, why the most
of our water bodies suffer on superfluos concentrations of phosphorus and thus
eutrophication and water quality deterioration. In this chapter some attention is focused on
the various traditional adsorbents (Fe-oxyhydroxide GEH104, montmorillonite, slovakite,
calsit, various deposit clinoptilolite-rich tuffs, alginite, Chinese slag, chitosan composed
zeolite), a few of the local repositories, which prove enhanced performance for phosphate
removal. Slovakian clinoptilolite-rich tuff effectively removed phosphate ions from waters.
Although, the montmorillonite, slovakite and GEH104 product proved slightly higher uptake
capacities towards phosphate ions at the ambient temperature than the clinoptilolite-rich tuff
did, the increased temperature of systems supported the uptake performance only by
clinoptilolite-rich tuff, not by montmorillonite and GEH104 adsorbents. The film-diffusion
was the rate-limiting step in all of the adsorbents examined, what simultaneously confirmed
the results of the applied Weber-Morris mass transfer model. Energetically lower surface
physisorption of phosphate onto clinoptilolite-rich tuff, GEH and montmorillonite, however
the chemisorption by slovakite was confirmed. Under the standard conditions the adsorption
of phosphate onto all adsorbents examined occurred spontaneously. The results of standard
free energies indicated simultaneously that the spontaneity slightly decreased with
temperature. The highest elution of phosphate was observed by montmorillonite (about
50%), while by clinoptilolite-rich tuff the elution with tap water was rather low. In dynamic
regime the best performance in phosphate uptake proved GEH product. According to MAS
NMR measurements the best symmetry in the spectrum of P-clinoptilolite indicated, that
Ca2+ cations are most frequently occurring in clinoptilolite-rich tuff framework and
dominant signal at chemical shift of 2.7-2.8 ppm may be assigned as surface precipitate
Ca3(PO4)2.
Keywords: Alginite, calsit, Chinese blust furnace slag, clinoptilolite-rich tuff
from various deposits, composed chitosan-zeolite, dynamic experiments,
granulated ferric hydroxide GEH, isotherm calculation, kinetics, MAS NMR,
montmorillonite-rich bentonite, phosphate elution, phosphate removal, SEM,
slovakite, soil farming, the point of zero charge (PZC), thermodynamics.
