Comparison of the efficiency of activated carbon and neutral polymeric adsorbent in removal of chromium complex dye from aqueous solutions.

The removal efficiency of chromium complex dye Lanasyn Navy M-DNL from aqueous solution using the activated carbon (AC) and the neutral polymeric adsorbent Macronet MN 200 (MN 200) has been investigated under various experimental conditions: initial dye concentration, pH and temperature. The effectiveness of MN 200 for the dye removal was found relatively higher than that of AC in both acidic and neutral solutions. Two theoretical models (pseudo-second-order-reaction and intraparticle diffusion) were used to describe the sorption kinetics, and to determine the constants of sorption rate (k(2)), intraparticle (k(i)) and film diffusion (k(s)). The both sorption systems dye-AC and dye-MN 200 follow the pseudo-second-order model with a higher k(2) value for dye-MN 200 in acidic media at 20 degrees C when compared with that of the dye-AC. With increase in the solution temperature from 20 to 40 degrees C the k(2) value for dye-AC indicate an increase in acidic media and decrease in alkaline media; whereas k(2) values for dye-MN 200 decrease in both acidic and neutral media. The rate of dye adsorption on both adsorbents is dependent on intraparticle and film diffusion proceeding simultaneously. The boundary layer effect is more pronounced in acidic solutions and with increase in temperature.

Performance of sulphonic cation exchangers in the recovery of ammonium from basic and slight acidic solutions.

Two sulphonated polystyrene-divinylbenzene cation exchangers (gel type Purolite SGC 100 x 10 MBH and macroporous Purolite C160 MBH) have been investigated for NH(4)(+) ions uptake from the ammonium-rich simulated solutions, corresponding to the caustic condensate of the nitrogen fertilizers production. One component (NH(3) or NH(4)NO(3)) solutions and the mixtures with varying molar ratio of these compounds have been used at the total concentration 0.214 mol/L. Batch and column experiments have been conducted to establish the influence of the matrix structure on the performance of the cation exchangers investigated during the sorption and the desorption. Batch sorption isotherms and breakthrough curves have shown the similar behaviour of the cation exchangers in the removal of NH(4)(+) and NH(3). On decreasing the influent pH from 11.4 to 5.74 a decrease in breakthrough capacity (BC) from 2.57 to 1.93 mol/L was observed. The distribution coefficients (K(d)), calculated from the batch sorption isotherms, are higher for the basic feed solution than for slightly acidic one. Both the degree of the cation exchanger regeneration (N/N(0)) and the efficiency of the NH(4)(+) ions recovery (N(R)), obtained using 0.7 bed volume (BV) of eluent (20% nitric acid) are lower for Purolite C 160 MBH than those for Purolite SGC 100 x 10 MBH. Using 5 BV of eluent the efficiency of the ammonium recovery amounted to 100% for both cation exchangers investigated. With respect to the efficiency of NH(4)(+) ions sorption and regeneration cation exchangers investigated are applicable for the recovery of ammonium ions from caustic condensate in the nitrogen fertilizers production.

Kinetic behaviour of Duolite ES 468 in the cosorption of non-ionic surfactant and copper(II).

Kinetic behaviour of the hydrogen form of Duolite ES 468 polyacrylic acid-functionalised cation exchanger with respect to the sorption of non-ionic surfactant alkylmonoethers (ALM-10) and copper(II) has been investigated; kinetic curves have been obtained, using spectrophotometric determination for ALM-10 and complexometric one for copper(II). Kinetic coefficient (B), intraparticle diffusion coefficient (D; m(2)s(-1)) and overall rate constant (k(o); s(-1)) for non-ionic surfactant and copper(II) depend on the solution composition, pH and the maximum sorption at the equilibrium. On increasing the solution acidity from pH 5 to pH 3 a decrease in both D and the equilibrium sorption for copper(II) although an increase in D for ALM-10 is observed. The action of copper(II) results in an increase in both D for ALM-10 and the maximum sorption at the equilibrium, whereas the action of ALM-10 leads to a decrease in the corresponding parameters for copper(II). Hydrogen form of Duolite ES 468 polyacrylic acid-functionalised cation exchanger is suitable for the simultaneous removal of non-ionic surfactant and copper(II) from waste water.