ADSORPTION OF CHLOROFORM AND TRICHLOROETHYLENE IN WATER WITH A NEW KIND OF HYPERCROSSLINKED RESINS

In this paper two newly developed hypercrosslinked resins were used to treat micropolluted drinking water and their static and kinetic adsorption were investigated at 293 K. The results show that these two adsorbents are superior to Amberlite XAD-4 for removing chloroform and trichloroethylene in aqueous solutions. The breakthrough capacity and the total capacities from mini-column adsorption studies for chloroform and trichloroethylene on XAD-4, ZH-01 and ZH-00 are calculated respectively under experimental conditions

EFFECT OF HYPERCROSSLINKED RESINS SURFACE CHEMISTRY ON THE ADSORPTION OF PHENOL FROM AQUEOUS SOLUTION

Two hypercrosslinked resins with similar physical characters but different surface chemistry were synthesized and used to remove phenol from aqueous solutions. The FTIR spectra, elemental analysis and the Boehm titration were used to characterize the chemical properties of the resins. The adsorption experiments were carried out using the bottle-point technique, and the effects of the surface chemistry on the adsorption were discussed. The adsorption data fit well with the Freundlich model, indicating the heterogeneity of the resins surface. It could be seen from the experimental results that the adsorption capacity increased with the increase in the total surface concentration of oxygen-containing groups. The pH dependence and the effects of ionic strength were also discussed. The kinetic adsorption data fit well with the pseudo-second order model, and the results showed that the surface oxygen-containing groups have little effect on the adsorption rate.

Two Organic Phase Suspension Polymerization for Novel Hypercrosslinked Resin Bead by Polycondensation of CMB

The suspension polymerization with two organic phases was adopted to prepare spherical hyper- crosslinked resin by self-polycondensation of 4,4＇-bis-（chloromethyl）- 1, 1＇-biphenyl （CMB）. The chemical structure,morphology and pore characteristics of the novel spherical resin were characterized with Fourier transform infrared spectroscopy （FTIR）, micrograph and Brunauer-Emmett-Teller （BET）. It is found that the suspension system and stirring speed impose a great influence upon the regularity and size distribution of hypercrosslinked beads. To prepare CMB resin beads with diameter of about 300 μm, the optimal condition is as follows： stirring speed 300 r·min^-1, and the volume ratio of the two organic phases （nitrobenzene/dimethyl silicon oil） 1 ： 5. After the self-polycondensation and sqccedent post-crosslinking of CMB monomer, the spherical adsorbent presents high spec^al surface area （1190 m^2· g^-1） and abundant pore^volume （0.714 cm^3· g^-1）, and could be potentially applied qn the adsorption of various organic molecules and synthesis of porous ion exchanger.

THE ADSORPTION BEHAVIORS OF 2,6-DICHLOROPHENOL ONTO HYPERCROSSLINKED RESINS

Experimental investigations were conducted on the adsorption characteristics of 2,6-dichlorophenol by two hypercrosslinked resins ZH-01 and XAD-4. The static adsorption was studied. Within temperature range of 288K-313K, the equilibrium adsorption date was fitted to freundlich adsorption isotherm models to evaluate the model parameters. The enthalpies, free energy, entropy were indicative of an exothermic, a spontaneous and disorder decreasing process. The magnitudes for 2,6-dichlorophenol on ZH-01 showed a chemisorption＇s transitions while on XAD-4 shows a physical adsorption process. The results showed that the ZH-01 adsorbents were better than the Amberlite XAD-4 for removing the 2,6-dichlorophenol in aqueous solutions.

Facile synthesis of hypercrosslinked resin via photochlorination of p-xylene and succedent alkylation polymerization

A combination of photochlorination ofp-xylene and succedent Friedel-Crafts alkylation polymerization was firstly used in the preparation of the hypercrosslinked adsorptive resin. The data of GC-MS and GC showed that a series of chlorizates were produced when p-xylene was photochlorinated. Hypercrosslinked resins could be synthesized by copolymerization, self-polymerization of chlorizates or post crosslinking reaction. The chemical structure and micromorphology of the porous resins were characterized by BET, FF-IR, SEM and elementary analysis （EA）. The results showed that the novel adsorptive resins possess high BET surface near to 1038 m^2/g and large pore volumes range from 0.5 to 1.2 cm^3/g.

ADSORPTION OF 2,4-D ON MODIFIED HYPERCROSSLINKED POLYSTYRENE(NDA-99)AND XAD-4 RESIN

The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid(2,4-D)in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent(NDA-99)modified by dimethylamine group as well as a nonionic macroporous adsorbent(XAD-4).The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism.It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix. Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin,which is in agreement with the IR spectroscopic results and the ΔE values of HOMO(the highest occupied molecular orbit)of adsorbent and LUMO(the lowest unoccupied molecular orbit)of adsorbate calculated from the MINDO/3 model.

Synthesis and application of a hydrophobic hypercrosslinked polymeric resin for removing VOCs from humid gas stream

A hydrophobic hypercrosslinked polymeric resin LC-1 was prepared and characterized. The properties of LC-1 resin were compared with those of a commercial hypercrosstinked polymer NDA-201 resin. In addition, the dynamic adsorption of trichloroethylene （TCE） onto LC-1 under dry and humid conditions at 303 K was investigated, the result shows that LC-1 possesses high hydrophobic property and can remove TCE from gas stream without effect of high humidity efficiently.

THERMODYNAMIC STUDY OF ADSORPTION OF PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTION BY A WATER-COMPATIBLE HYPERCROSSLINKED POLYMERIC ADSORBENT

Equilibrium data for the adsorption of phenolic compounds, i.e., phenol, p-cresol, p-chlorophenol and p- nitrophenol from aqueous solutions by a water-compatible hypercrosslinked polymeric adsorbent (NJ-8) within temperature range of 283-323 K were obtained and correlated with a Freundlich-type of isotherm equation, so that equilibrium constants KF and n were obtained. The capacities of equilibrium adsorption for all the four phenolic compounds on the NJ-8 from aqueous solutions are around 2 times as high as those of Amberlite XAD-4, which may be attributed to the unusual micropore structure and the partial polarity on the network. The values of the enthalpy (always negative) are indicative of an exothermic process, which manifests the adsorption of all the four phenolic compounds on the two polymeric adsorbents to be a process of physical adsorption. The negative values of free energy change show that the solute is more concentrated on the adsorbent than in the bulk solution. The absolute free energy values of adsorption for NJ-8 are always higher than those for Amberlite XAD-4, which indicates that phenolic compounds are preferentially adsorbed on NJ-8. The negative values of the adsorption entropy are consistent with the restricted mobilities of adsorbed molecules of phenolic compounds as compared with the molecules in solution. The adsorption entropy values of phenolic compounds for NJ-8 are lower than those for Amberlite XAD-4, which means the micropores of NJ-8 require more orderly arranged adsorbate.

Adsorption mechanism of phenolic compounds from aqueous solution on hypercrosslinked polymeric adsorbent

The adsorption of two phenols, namely, phenol and salicylic acid(SA) onto a water-compatible hypercrosslinked polymeric resin(NJ-8) were studied in terms of pseudo-second-order and first order mechanisms for chemical sorption as well as an intraparticle diffusion mechanism process. Kinetic analysis showed that the intraparticle diffusion process was the essential rate-controlling step. The activation energies of sorption have also been evaluated with the pseudo-second-order and intraparticle diffusion constants, respectively. Adsorption equilibrium data were well fitted by the Langmuir, Freundlich and Redlich-Peterson isotherms. Adsorption was exothermic and basically of a type of transition between physical and chemical character. The sorption capacity was higher for SA due to its more hydrophobic. Phenol has a higher adsorption enthalpy since it could form stronger hydrogen bonding on NJ-8.

Preparation of a novel magnetic powder resin for the rapid removal of tetracycline in the aquatic environment

Magnetic powder resin Q150 with high specific surface area of 1074 m2/g was prepared by the membrane emulsificationsuspension polymerization technique. Adsoption of tetracycline on the obtained sorbent Q150 was evaluted by using the granule resin （GR） XAD-4, the powder activated carbon （PAC） 1240AC and the granule activated carbon （GAC） HD4000 for comparison. It was found that Q150 had a larger adsorption capacity, faster kinetic and easier regeneration under alkaline condition. The results suggested that the powder resin （PR） Q150 would be a promising sorbent for removing antibiotics and even other organic micropollutants from the aquatic environment.