Ground Types for Seismic Design in Romania

Use of polyethylene films photografted with 2‐(dimethylamino)ethyl methacrylate as a potential adsorbent for removal of chromium (VI) from aqueous medium

“…49,52 However, for the pseudo-second order equation, the good linearity of t/Q t against t was obtained for much longer immersion times as shown in Table I. It was found from these results that the experimental data in this study fit to the pseudo-second-order model much better than the pseudo-first-order model, 1,3,17,[23][24][25]28,32,50,51 and the adsorption capacity values at calculated using eq. (6) were much close to the adsorption capacity at equilibrium.…”

“…This adsorption capacity was higher than or comparable to those of other adsorbents prepared for Cr(VI) ion adsorption. 1,3,[21][22][23][24][25]43 The low values of the adsorption ratio would be attributed to the fact that Cr(VI) ion adsorption is restricted to the easily accessible outer surface region of the grafted layer. 25 This means that some of the protonated dimethylamino groups on a grafted polymer chain present inside the grafted layer swollen is not involved in adsorption of Cr(VI) ions at higher grafted amounts.…”

“…For all of the PE-g-PDMAEMA films used, although the adsorption capacity was almost constant against the initial K 2 Cr 2 O 7 concentration, these values were much higher than or comparable to those of other polymeric adsorbents prepared for Cr(VI) ions. 1,3,[21][22][23][24][25]43 The Langmuir adsorption constant obtained from the y-intercept ranged from 81.4 to 100 dm 3 /mmol corresponding to 1.56-1.92 dm 3 /mg with an average of 91.4 dm 3 /mmol corresponding to 1.76 dm 3 /mg. This average value was higher than the Langmuir adsorption constant values shown in other articles dealing with adsorption of Cr(VI) ions obeying the Langmuir equation.…”

“…8 However, adsorption is a superior process compared to others in terms of cost, simplicity of design and operation, availability, effectiveness, and insensitivity to toxic substances. Different types of adsorbents, such as activated carbon, [9][10][11] sawdust, [12][13][14] chitosan and modified chitosan, [15][16][17] biomass materials, 18 and synthetic polymers 1,3,[19][20][21][22][23][24][25] have been used for removal of Cr(VI) ions from aqueous medium. Unfortunately, some of these adsorbents do not have high adsorption capacities, and others have difficulty in regeneration or reuse.…”

“…So they have been successfully used for adsorption of Cr(VI) ions. 1,[19][20][21]23,24 Many research groups have investigated adsorption behavior of polymeric adsorbents, such as chitosan beads and their modified products, [26][27][28] chemically crosslinked poly(4-vinylpyridine) (4-VP) beads, and polymer substrates grafted with 4-VP, 19,20,23,24,29,30 poly(glycidyl methacrylate) (PGMA) functionalized with 1,6-diaminohexane, 31 diethylene triamine, 25 and branched polyethyleneimine. 1,32 However, 4-VP is little photografted onto the polyethylene (PE) and polypropylene (PP) substrates by the photografting technique with ultraviolet (UV) rays.…”