Sorption of aromatic sulfonates onto two aminated polystyrene sorbents with different pore structures (M-101 and D-301) was investigated for optimization of their potential application in chemical wastewater treatment. Sodium benzenesulfonate (BS), sodium 2-naphthalene sulfonate (2-NS) and disodium 2,6-naphthalene disulfonate (2,6-NDS) were selected as reference solutes and sodium sulfate was as a competitive inorganic salt. Sorption selectivity of both sorbents is dependent upon the concentration levels of aromatic sulfonates in solution coexisting with sodium sulfate at a high level. However, both sorbents exhibit different characters. D-301 presents more favorable sorption for the solutes at relatively high levels (e.g., higher than 5 mM for BS, 0.7mM for 2-NS and 0.05mM for 2,6-NS), while M-101 removes aromatic sulfonates more completely when the solute concentration kept at relatively low levels. Based on the experimental results, we proposed an integral process of sorption onto D-301 followed by secondary-sorption onto M-101 to remove aromatic sulfonates from industrial wastewater completely and economically. Furthermore, the satisfactory performance revealed from large-scale application further demonstrated the feasibility of extending this process to dispose of other associated chemical wastewaters.

Titanium phosphate (TiP) exhibits preferable sorption toward lead ion in the presence of competing calcium ions at high levels, however, it is present as fine or ultrafine particles and cannot be directly employed in fixed-bed or any flow-through systems due to the excessive pressure drop and poor mechanical strength. In the present study a new hybrid sorbent TiP-001 was fabricated by impregnating titanium phosphate (TiP) nanoparticles onto a strongly acidic cation exchanger D-001 for enhanced lead removal from waters. D-001 was selected as a host material mainly because of the Donnan membrane effect resulting from the immobilized sulfonic acid groups bound on the exchanger matrix, which would enhance permeation of the target metal cation prior to effective sequestration. TiP-001 was charac-terized by transmission electron micrograph (TEM), X-ray diffraction (XRD), and pH-titration. Batch and column sorption onto TiP-001 was assayed to evaluate its performance as compared to the host exchanger D-001. Lead sorption onto TiP-001 is a pH-dependent process due to the ion-exchange nature, and its sorption kinetics follows the pseudo-second-order model well. Compared to D-001, TiP-001 displays highly selective lead sorption in the presence of competing calcium cations at concentration of several orders higher than the target metal. Fixed-bed sorption of a synthetic feeding solution indicates that lead retention by TiP-001 results in a conspicuous decrease of this toxic metal from 0.50 to below 0.010mg/L (drinking water standard recommended by WHO). Moreover, its feasible regeneration by dilute HCl solution also favors TiP-001 to be a feasible sorbent for enhanced lead removal from water.

The removal of phenol from aqueous solution was examined by using a porous acrylic ester polymer (Amberlite XAD-7) as an adsorbent. Favorable phenol adsorption was observed at acidic solution pH and further increase of solution pH results in a marked decrease of adsorption capacity, and the coexisting inorganic salt NaCl exerts positive effect on the adsorption process. Adsorption isotherms of phenol were linearly correlated and found to be well represented by either the Langmuir or Freundlich isotherm model. Thermodynamic parameters such as changes in the enthalpy (△H), entropy (△S) and free energy (△G) indicate that phenol adsorption onto XAD-7 is an exothermic and spontaneous process in nature, and lower ambient temperature results in more favorable adsorption. Kinetic experiments at different initial solute concentrations were investigated and the pseudo-second-order kinetic model was successfully represented the kinetic data. Additionally, the column adsorption result showed that a complete removal of phenol from aqueous phase can be achieved by XAD-7 beads and the exhausted adsorbent was amenable to an entire regeneration by using ethanol as the regenerant. More interestingly, relatively more volume of hot water in place of ethanol can also achieve a similar result for repeated use of the adsorbent.

The current study reports a potential process to selectively separate and preconcentrate tartaric acid from its simulated industrial effluent. It was achieved by sorption onto a tailored polymeric ligand exchanger. The polymeric ligand exchanger is essentially a copper(II)-bound specialty chelating polymer (denoted D-Cu). Effect of solution pH and competing sulfate on tartaric acid sorption onto D-Cu was also included in the study. Compared to a weakly basic anion exchanger D-301, D-Cu exhibits more favorable sorption of tartaric acid from aqueous media coexisting with Na2SO4 at a high level. The exhausted D-Cu was amenable to an entire regeneration by the diluted NaCl solution. Results of column sorption tests further demonstrated the feasibility of D-Cu for selective separation and preconcentration of tartaric acid from the simulated wastewater for its further recovery.