Ai Min Li

Adsorption Behaviors of Oxytetracycline on Synthetic Resins

Three commercial resins (NDA150, NDA88 and NDA77) with different physicochemical properties were selected to investigate the adsorption behavior and primary factors controlling the adsorption of oxytetracycline (OTC) onto the resins. The adsorption kinetics of OTC onto all resins were fitted well to pseudo-second-order model. NDA150 had the largest adsorption capacity due to its higher surface area and larger total pore volume. Moreover, all of the three resins exhibited nearly the same equilibrium time because of their nearly the same particle size. The suitable pH for the effective adsorption of NDA150 and NDA77 is from 4 to 7, while the ideal pH for NDA88 is 10. OTC adsorption on all of the three resins increased with the increasing ionic concentration.

Preparation of Manganese Oxide Supported on Activated Carbon and its Application in Catalytic Ozonation of 4-Chlorophenol

Catalyst with manganese oxide highly dispersed on granular activated carbon (MnOx/GAC) was fabricated by impregnating GAC in MnCl2 solution and characterized by several techniques. The performance of manganese catalyst was investigated in catalytic ozonation of 4-chlorophenol in water. Manganese catalyst exhibits better efficiency than the original granular activated carbon, due to the synergic effect between activated carbon and manganese oxide. MnOx/GAC, produced by a simple methodin situ, is promising in catalytic ozonation of refractory organic pollutants in waste water.

Effects of Adding Nitrifying Bacteria on Microbial Communities and Nitrification in a Laboratory-Scale a/O Reactor Treating Leather-Tanning Wastewater

A laboratory-scale anoxic/oxic reactor was used to analyze the effects of adding nitrifying bacteria on microbial communities in the treatment of leather-tanning wastewater. The reactor was operated in series in continuous flow mode for 25 d after an acclimation period of 45 d, and the nitrifying bacteria were added after the acclimation period. The addition of nitrifying bacteria into the wastewater significantly enhanced NH4+-N removal efficiency. The Arrhenius and Jacob-Monod models were applied to determine the optimum and acceptable operating conditions for this process. The optimum temperature range and concentration of dissolved oxygen were 15-30 oC and 5 mg L-1, respectively. Use of Nitrosomonas europaea and Nitrobacter were considered reliable for leather-tanning wastewater treatment due to their dominant status as nitrifying bacteria. Substrate half-saturation constants for ammonia oxidizing bacteria and nitrite oxidizing bacteria were 24.13 mg L-1 and 5.43 mg L-1, respectively.

Preparation of Uniform Hypercrosslinked Microspheres with Large Specific Surface Area

The membrane emulsification-suspension polymerization (MESP) method was used to synthesize hypercrosslinked microspheres with a narrow size distribution. The resulting polymers possessed large specific surface area (over 1300 m2/g) and their particle size was controllable. The particles were more hydrophilic when using nitrobenzene as solvent instead of 1, 2-dichloroethane in the postcrosslinking process.

Adsorption Behaviors of Chlortetracycline on Granular Activated Carbons

The adsorption behaviors of chlortetracycline on two kinds of granular activated carbons with different BET surface area and average pore width have been studied. The results show that larger BET surface area is beneficial for the adsorption capacity, and wider pore structure can enhance the adsorption rate. Initial solution pH has great effect on the adsorption behavior, and the suitable pH for the effective adsorption is from 4 to 8.

Solid-Phase Extraction of Trace Antibiotics Using New Hypercrosslinked Polymer as Adsorbent

Three new hypercrosslinked polymers were used as solid phase extraction packings to enrich Chlortetracycline (CTC) in water. Through the comparison, the NDS-1 column has higher performance than the other two, almost the same as commercial columns HLB on the enrichment of the Chlortetracycline.

New Hypercrosslinked Polymer Adsorbents for Solid Phase Extraction of Polar Compounds

Membrane emulsification-suspension polymerization method was introduced to prepare the monodisperse hypercrosslinked adsorbents ZQ-1 and ZQ-2 which can be used in solid phase extraction (SPE). Compared with the commercially available adsorbent LichrolutEN, ZQ-1 exhibits obvious superiority for five conventional polar analytes owing to its large specific surface area, hydrophilic groups and small particle size.

The Effect of Metal Ions on the Removal of Natural Organic Acids by Bi-Functional Resin

In this paper, based on the previous studies of natural organic acids adsorbed onto bi-functional resin, the influence of metal ions on the adsorption of humic, tannic and gallic acids by bi-function resin WJN-06 were systematically investigated. Low concentration of Ca2+ and Mg2+ in solution could decrease the resin’s adsorption capacity for gallic acids, but increased the removal rate of humic and tannic acids. Low concentration of Cu2+ and Pb2+ in solution could enhance the uptake of these three natural organic acids. However the high concentration of metal ions in solution could decrease the adsorption capacity of bi-functional resin for humic, tannic and gallic acids.

Adsorption of Phenol on Bifunctional Resin and Granular Activated Carbon Preloaded by Tannic Acid

For comparing the adsorption of Synthetic Organic Chemicals (SOC) competing with background pollutants between a bifunctional resin and a commercial granular activated carbon (GAC), tannic acid (TA) was preloaded to the two adsorbents at quantities of 60 and 120 μmol/g. As a result, decreases of micropores volume in the resin were 75.5 and 98.9%, while those in the GAC were only 19.0 and 30.0%, respectively. Preloading attenuated surface heterogeneities and phenol’s capacities of two adsorbents distinctly. But maximumly, 1.0 mole TA’s preloading on GAC could decline 9.23 mole phenol’s adsorption. Under the same condition, the resin’s capacity of phenol was only descended at 2.68 times, when 98.9% micropores have been blocked. In kinetic tests, blockages in the resin were misapprehended to be much lighter than those in the GAC by the Homogeneous Surface Diffusion Model (HSDM). One steady operation engineering at micropore volume 37.8% decline was introduced. The conflicts were explained by quite a number of resin’s functional groups in the macroporous and mesoporous region could attract enough phenol molecular rapidly, even if almost all micropores were blocked.