The adsorption of tannic acid on hydrophilic cotton and its effect on the electrokinetic properties of this cellulose fibre in a cationic dye solution

Abstract

Data on the adsorption of tannic acid on the hydrophilic cotton a t different temperatures arc presented. The thermodynamics of the adsorption equilibria of tannic acid is investigated, and it is established that the increase in temperature decreases the amount of tannic acid adsorbed. The adsorption equilibria of tannic acid are described by the FREUND-LICH adsorption isotherm. Also, an experimental investigation on streaming potentials of cellulose/tannic acid/Rhodamine B solutions system is described and the effect of the mordant on the electrokinetic properties of cellulosic fibres dyed with a cationic dye is analyzed. The behaviour of the electrokinetic potential could be explained mainly by the H-bonds formed between the phenolic hydroxy groups of tannic acid and the carboxy groups of cellulose and by the electrostatic attraction between the dye cation and the surface of the fibre. Die Adsorption von Tannin a n hydrophiler Baurnwollt! und ihr Einflup auf die elektrokinetischen Eigenschaften der Cellulosefasern in einer kationischen FarbstofflosungMefiergebnisse zur Adsorption von Tannin auf hydrophiler Baumwolle bei unterschiedlichen Temperaturen werden vorgestellt. Die Thermodynamik des Adsorptionsgleichgewichtes des Tannins wird untersucht. Mit zunehmender Temperatur nimmt die Menge des adsorbierten Tannins ab. Das Adsorptionsgleichgewicht des Tannins lafit sich durch eine Adsorptionsisotherme nach FREUNDLICH beschreiben. Weiterhin wurde das Stromungspotential des Systems Cellulose/Tannin/Rhodamin-B-Losung untersucht, und der EinfluB der Beize auf die clektrokinetischen Eigenschaften der mit einem kationischen Farbstoff gefarbten Cellulosefasern wurde analysiert. Das Verhalten des elektrokinetischen Potentials konnte im wesentlichen durch die Bildung von H-Brucken zwischen den phenolischen Hydroxylgruppen dcs Tannins und den Carboxygruppen der Cellulose sowie durch die elektrostatisclie Anziehung zwischen dem Farbstoff-Kation und der Faseroberflache erklart werden. A&op6tpa mannuna zuapo@ubnb&a xnonKoM u ee sfiuxnue Ha aneicmpo~unemuuec~ue csoiicmsa yefimono3nbax sofio-Eon s pacmsope Kamuonnbax I;pacumeaefi kl3yqeHa agcop6qna TaHHHHa rHApO@HJIbHbIM XJIOIIKOM IIpH pa3JIMqHbIX TeMIlepaTypaX, a TaKWe TepMOgHHaMHKa paBHOBeCHR a~c o p 6 q m TaHHHHa. YCTaHOBJIeHo, 41'0 KOJIHZIeCTBO aACOp6HpyeMOrO T a H H H H a yMeHbUIaeTCR C yBenH-YeHMeM TeMlIepaTypbI. A~COp6qHOHHOe PaBHOBeCHe MOWHO OnIICbIBaTb agCOp6qHOHHOfi M30TepMOii no ( D P E~~H~J I H X Y . KpOMe TOP0 H3yqeH IIOTeHUHaJl IIOTOKa B CHCTeMe UenJlIoJIO3a-TaHHIIM-paCTBOp pOAaMIIHa 6 II npoBegeH a~aa113 BJIARHHR IIpOTpaBbI H a 3JIeKTpOKHHeTHZIeCKHe CBOfiCTBa IJeJIJIIOJIO3HbIX BOJIOKOH, OKpalUeHHbIX KaTHOHHbIM KpaCH-TeJIeM. kl3MeHeHHR 3JIeKTPOKHHeTHYeCKOrO IIOTeHUHaJIa MOWHO O6'bRCHHTb, B OCHOBHOM, 06pa30BaHMeM BOgOpOA-HbIX CBH3efi MeWgy (PeH0JIbHbIM.R rHApoKCMJIbHbIMm rpynnaMH T a H H A H a H KaP6OKCHnbHbIMH rpynnaMH qexnmno3b1, a TaKWe 3JIeKTpOCTaTH' IeCKHM IIpIITHHteHHeM MeWBy KaTHOHHbIM KpaCIITeJIeM H IIOBepXHOCTbH, BOJIOKHB.

Surface Free Energy, Adsorption and Zeta Potential in Leacril/Tannic Acid System

“…Both the adsorption kinetic (from 5 × 10 -5 M solution) and adsorption isotherms were determined at 275, 283, 293, and 303 K. The adsorbed amounts were established from the difference between the initial and final (or at the moment of the measurements) concentrations. The concentrations were determined using spectrophotometer model U-2000 (Hitachi). , The maximum absorbance was at λ = 271 nm. The adsorption equilibrium has been attained within 2−3 h. However, the adsorption measurements were conducted up to 24 h. To determine kinetics of the adsorption, first it was measured every second minute, up to the 32nd minute of the process duration, then every 4−5 min, and later for longer periods of time.…”

Effect of Tannic Acid on the Surface Free Energy of Cotton Fabric Dyed with a Cationic Dye

“…The The decreasing negative zeta potential with increasing con-reproducibility of these experiments was very good, therecentration of tannic acid is a result of H / ion adsorption, fore we can consider the values as confident ones. The Lifwhich is known as a potential determining for such cellulose shitz-van der Waals values of the surfaces (Table 2) are in fabric (15). Similar changes of zeta potential for cellulose the range for other solids (31)(32)(33)(34), and the changes caused fabric/tannic acid systems were observed using the stream-by the treatment processes are in the range of 14 mJ/m 2 .…”

“…In our other papers ( 15,16 ) the adsorption of tannic is important for better insight into the processes occurring acid and the electrokinetic potential of the acid treated at the interfaces, both in pure and applied science. Many cotton have been studied.…”

“…The standard deviation is marked on the figures with vertical bars. In many cases they are acquire a larger number of carboxyl groups (15,16).…”

“…Similar changes of zeta potential for cellulose the range for other solids (31)(32)(33)(34), and the changes caused fabric/tannic acid systems were observed using the stream-by the treatment processes are in the range of 14 mJ/m 2 . ing potential technique (15,16). The presence of NaCl in They are in accord with those obtained for Leacril fabric the solution decreases the negative zeta potential, which im-(18), but the changes run a bit differently in comparison to plies that Cl 0 ions probably adsorb on the tannic acid treated those of polyester (17).…”