title: Effect of formaldehyde on Cu(II) removal from synthetic complexed solutions by ion exchange.
abstract: The effect of formaldehyde (HCHO) on the ion exchange of Cu(II) from an equimolar EDTA (ethylenediaminetetraacetic acid, H(4)L) solution with a strong-base Amberlite IRA-400 resin was studied. Experiments were conducted as a function of the initial concentration of Cu(II) (0.5-10 mM), solution pH (1.0-6.0), HCHO concentration (0-6 vol%), and temperature (15-35 degrees C). It was shown that the amount of exchange of Cu(II), which exists in the form of complexed anions CuL(2-), increased with increasing solution pH and reached a plateau at an equilibrium pH (pH(e)) of 3.5. However, the amount of exchange decreased with increasing HCHO concentration up to 3 vol% but then slightly decreased with a further increase in HCHO concentration. Such effect of added HCHO was determined by the following two factors: the competitive exchange of HCOO(-) anions and the enhanced exchange of Cu(I) in the form of complexed anions CuL(3-). The exchange isotherm obtained at a fixed pH(e) could be well described by the Langmuir equation. The isosteric enthalpy change for the present ion exchange process was also evaluated and discussed.
authors.affiliation: Department of Chemical Engineering and Materials Science, Yuan Ze University, Chung-Li 320, Taiwan. rsjuang@ce.yzu.edu.tw
authors.forename: Ruey-Shin
authors.initials: RS
authors.lastname: Juang
authors.forename: Su-Hsia
authors.initials: SH
authors.lastname: Lin
authors.forename: Hsiang-Chien
authors.initials: HC
authors.lastname: Kao
authors.forename: Ming-Huei
authors.initials: MH
authors.lastname: Theng
mesh_terms: D003300:Copper / Q000737:chemistry / Q000302:isolation & purification*; D004492:Edetic Acid / Q000737:chemistry; D005557:Formaldehyde / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007475:Ion Exchange Resins / Q000737:chemistry*; D011108:Polymers; D018508:Water Purification / Q000379:methods
chemical_list: D007220:Industrial Waste; D007475:Ion Exchange Resins; D011108:Polymers; D005557:Formaldehyde; D003300:Copper; C050187:amberlite IRA 400; D004492:Edetic Acid