A hydrophilic hyper-cross-linked polymer resin NDA-150 was developed to remove 1-naphthol from the contaminated waters. The sorption performance of 1-naphthol on NDA-150 was explored and compared with that on the commercial hydrophobic resin XAD-4. The sorption rates of 1-naphthol onto both of the two resins obey the pseudo-second-order kinetics, and are limited by the successive steps of film diffusion and intraparticle diffusion. The greater sorption rate on XAD-4 than NDA-150 is probably due to the larger average pore diameter of XAD-4. All the adsorption isotherms can be represented by Langmuir equation. The larger capacity and stronger affinity ofNDA-150 than XAD-4 probably result fromthe abundant microporous structure and polar groups of NDA-150. In aqueous phase hydrophobic XAD-4 adsorbs 1-naphthol driven principally by enthalpy change, while the adsorption onto hydrophilic NDA-150 driven mainly by entropy change. The breakthrough and the total sorption capacity of NDA-150 to 1-naphthol were obtained to be 1.10 and 1.58mmolmL−1 resin at 293K, respectively. Nearly 100% regeneration efficiency for the resin was achieved by ethanol at 313K.

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.

Hydrated ferric oxide-loaded hybrid sorbents are of considerable concern for arsenic removal from waters. In the current study, several nanosized hydrated ferric oxide (HFO)-loaded polymer sorbents were prepared and assayed to examine the effect of HFO loadings on arsenate sorption from aqueous solution. Batch and column sorption studies showed that the sorption capacity of arsenate increased with the increase of HFO loadings from 3 to 15% (in Fe mass); however, a further increase in the HFO loadings resulted in a dramatic decrease of the sorption capacity. At relatively low arsenate levels (e.g., <1mg/L), sorbents with lower HFO loadings exhibited higher distribution coefficients (Kd) than others, implying that HFO loaded at a relatively lower level exhibits stronger sorption affinity toward arsenate than the larger one. However, at relatively high arsenate levels, the sorbent with HFO loading of 15% displayed the highest sorption capacity. Additionally, all the exhausted sorbents are amenable to an efficient regeneration by a mixed NaOH-NaCl solution irrespective of their HFO loadings. The results obtained in the current study may serve as a reference for preparation of other hybrid sorbents with similar structures, i.e., composites of nanosized metal (hydro)oxide particles and porous substrates.

In the current study, amorphous titanium phosphate (TiP) was prepared as an adsorbent for heavy metals from waters. Uptake of Pb2+, Zn2+, and Cd2+ onto TiP was assayed by batch tests; a polystyrene -sulfonic acid exchanger D-001 was selected for comparison and Ca2+ was chosen as a competing cation due to its ubiquitous occurrence in waters. The pH-titration curve of TiP implied that uptake of heavy metals onto TiP is essentially an ion-exchange process. Compared to D-001, TiP exhibits more preferable adsorption toward Pb2+ over Zn2+ and Cd2+ even in the presence of Ca2+ at different levels. FT-IR analysis of the TiP samples laden with heavy metals indicated that the uptake of Zn2+ and Cd2+ ions onto TiP is mainly driven by electrostatic interaction, while that of Pb2+ ions is possibly dependent upon inner-sphere complex formation, except for the electrostatic interaction. Moreover, uptake of heavy metals onto TiP approaches equilibrium quickly and the exhausted TiP particles could be readily regenerated by HCl solution.

In the present study, a novel hybrid sorbent ZrP-001 was prepared by loading zirconium phosphate (ZrP) onto a strongly acidic cation exchanger D-001. Sorption behavior of Pb2+, Zn2+, and Cd2+ onto ZrP-001 was experimentally examined by comparing with the host exchanger D-001. ZrP-001 was characterized by scanning electron micrograph (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), pH-titration and pore size distribution analysis. Sorption of the heavy metals onto ZrP-001 was found to be pH-dependent due to the ion exchange mechanism. Compared to D-001, a smaller pore size of ZrP-001 due to the ZrP dispersion consequently resulted in a lower sorption rate. Competitive effect of Ca2+ on sorption of heavy metals onto ZrP-001 and D-001 was compared to elucidate sorption preference of the hybrid sorbent towards heavy metals. More favorable sorption of ZrP-001 than D-001 was observed for all the three metals and their sorption preference onto ZrP-001 followed the order Pb2+> >Zn2+ ≈Cd2+. Fixed-bed sorption results and its efficient regeneration property further demonstrated that ZrP-001 is a potential candidate for removing heavy metals from contaminated water.