CR-100 synthetic zeolite adsorption characteristics toward Northern Banat groundwater ammonia

Abstract

The adsorption characteristics of synthetic zeolite CR-100 in a fixed-bed system using continuous flow of groundwater containing elevated ammonia concentration were examined. The possibilities for adsorbent mass calculation throughout mass transfer zone using novel mathematical approach as well as zeolite adsorption capacity at every sampling point in time or effluent volume were determined. The investigated adsorption process consisted of three clearly separated steps indicated to sorption kinetics. The first step was characterized by decrease and small changes in effluent ammonia concentration vs. experiment time and quantity of adsorbed ammonia per mass unit of zeolite. The consequences of this phenomenon were showed in the plots of the Freundlich and the Langmuir isotherm models through a better linear correlation according as graphical points contingent to the first step were not accounted. The Temkin and the Dubinin-Radushkevich isotherm models showed the opposite tendency with better fitting for overall measurements. According to the obtained isotherms parameter data, the investigated process was found to be multilayer physicochemical adsorption, and also that synthetic zeolite CR-100 is a promising material for removal of ammonia from Northern Banat groundwater with an ammonia removal efficiency of 90%.

Ammonium ion removal from aqueous solutions using fly ash derived zeolites by alkaline fusion

“…Sa Slike 2 je vidljivo da zeoliti UF i SF postižu ravnotežna stanje nakon 24 h, dok je za uzorak GF neophodno 48 h. Prema literaturnim navodima adsorpcija amonijum-jona, na zeolitima sintetizovanim od LP termoelektrana, je brz proces. Adsorpcija se najvećim dijelom odigrava u prvih 10 -15 min [19], ili 30 minuta [20], a kao ravnotežno vrijeme često je primijenjivano 1,25 h [14], 2 h [21], ali i 24 h [22]. Takođe, pojedini autori navode da je za zeolite sa velikim sadržajem kalcijuma potrebno nešto duže vrijeme za postizanje ravnotežnog stanja, tačnije oko 60 min [7], što je potvrđeno i u ovom radu za uzorak GF, koji postiže ravnotežno stanje za 48 h (Slika 2).…”

“…Za uzorak GF efikasnost uklanjanja se bitnije ne mijenja i iznosi 20,8 % pri najvećoj početnoj koncentraciji, dok je na najmanjoj 20,9 %, uz izrazit skok u porastu efikasnosti na 38,6 % pri početnoj koncentraciji od 34,6 mg NH 4 + /dm3. Povećavanje kapaciteta adsorpcije pri većim početnim koncentracijama, uz istovremeno smanjenje efikasnosti može se objasniti povećavanjem gradijenta koncentracije, koji je veći što je početna koncentracija veća, a broj mjesta za adsorpciju manji [21,24]. Sa Slike 3 vidljivo je da Lengmirov i Tempkinov model daju skoro identične krive za uzorke UF i SF i da ovi modeli najbolje opisuju adsorpcione izoterme amonijum-jona na C e / mg NH4 + dm -3 C e / mg NH4 + dm -3 C e / mg NH4 + dm -3 ◼ ekspetiment ____ Lengmir _ _ _ Frojndlih ---Temkin - - -Dub.…”

“…Tempkinov model pretpostavlja da se toplota adsorpcije svih molekula u sloju smanjuje linearno sa povećavanjem stepena pokrivenosti površine adsorbenta. Pozitivne vrijednosti energije adsorpcije (bT), kod svih ispitivanih uzoraka, pokazuju da se sa porastom temperature kapacitet adsorpcije povećava što je evidentno i u radovima drugih autora [14,21]. Koeficijenti determinacije kod Dubinjin-Raduškevičevog modela za uzorke iznose UF (R 2 =0,9307); SF (R 2 =0,9653) i GF (R 2 =0,9551).…”

Application of the adsorbent CR-100 for Ammonium Removal: Thermodynamic and Kinetic Studies

“…[4][5][6][7] The affinity of ammonia to adsorb on the surface of different solid materials significantly influences the selection of its removal process. [8][9][10] There are various adsorbent materials in nature that are successfully applied for this purpose, [11][12][13][14] such as zeolites, [15][16][17][18][19][20][21] clay minerals, activated carbon, exfoliated vermiculites, fly ash, peats, chitosan beads, wood sawdust, bentonite, attapulgite, oxide nanoparticles, and zero-valent iron that have ion exchange and adsorption properties. [22][23][24][25][26][27][28] Crystal-Right™ (CR-100) is one of the most durable synthetic mesoporous aluminosilicate used for commercial purposes [29] and has the ability to increase the pH value, to reduce water hardness and remove iron and manganese ions [30] during the filtration process.…”