Competitive effects of humic acid and wastewater on adsorption of Methylene Blue dye by activated carbon and non-imprinted polymers

Natural organic matter（NOM）, present in natural waters and wastewater, decreases adsorption of micropollutants, increasing treatment costs. This research investigated mechanisms of competition for non-imprinted polymers（NIPs） and activated carbon with humic acid and wastewater. Three different types of activated carbons（Norit PAC 200,Darco KB-M, and Darco S-51） were used for comparison with the NIP. The lower surface area and micropore to mesopore ratio of the NIP led to decreased adsorption capacity in comparison to the activated carbons. In addition, experiments were conducted for single-solute adsorption of Methylene Blue（MB） dye, simultaneous adsorption with humic acid and wastewater, and pre-loading with humic acid and wastewater followed by adsorption of MB dye using NIP and Norit PAC 200. Both the NIP and PAC 200 showed significant decreases of 27% for NIP（p = 0.087） and 29% for PAC 200（p = 0.096） during simultaneous exposure to humic acid and MB dye. There was no corresponding decrease for NIP or PAC 200 pre-loaded with humic acid and then exposed to MB. In fact, for PAC 200, the adsorption capacity of the activated carbon increased when it was pre-loaded with humic acid by 39%（p = 0.0005）. For wastewater, the NIP showed no significant increase or decrease in adsorption capacity during either simultaneous exposure or pre-loading. The adsorption capacity of PAC 200 increased by 40%（p = 0.001） for simultaneous exposure to wastewater and MB. Pre-loading with wastewater had no effect on MB adsorption by PAC 200.

Use of sub-micron sized resin particles for removal of endocrine disrupting compounds and pharmaceuticals from water and wastewater

Endocrine disrupting compounds（EDCs） and pharmaceuticals pose a challenge for water and wastewater treatment because they exist at very low concentrations in the presence of substances at much higher concentrations competing for adsorption sites.Sub-micron sized resin particles（approximately 300 nm in diameter）（SMR） were tested to evaluate their potential as a treatment for EDCs including：17-β estradiol（E2）,17-α ethinylestradiol（EE2）,estrone（E1）,bisphenol A（BPA）,and diethylstilbestrol（DES） as well as 12 pharmaceuticals.SMR were able to remove 98%of spiked E2,80%of EE2,87%of BPA,and up to 97%of DES from water.For a 0.5 ppm mixture of E2,EE2,E1,BPA and DES,the minimum removal was24%（E2） and the maximum was 49%（DES）.They were also able to remove the pharmaceuticals from deionized water and wastewater.Overall,SMR are a promising advanced treatment for removal of both EDCs and pharmaceuticals.

Elimination of Surfactants and Small Dyes from Water with Silicasupported Dendritic Amphiphiles

Silica-supported branched polyethylenimine（Sil@PEI） is a conventional adsorbent and shows a limited affinity to anionic surfactants and small dyes（K = 106？107 L/mol）. If the PEI is alkylated with cetyl groups（C16）, the K of the resulting adsorbents（Sil@PEI@C16-x, where x is the fraction of PEI units being alkylated） is significantly improved. Optimization shows that Sil@PEI@C16-0.15 can best reduce aqueous surfactants to a residue around 10？10 mol/L; while Sil@PEI@C16-0.6 can reduce even small aqueous dyes to a residue below 10？10 mol/L, nearly 105-fold lower than that by Sil@PEI. The adsorbents are well recyclable. It is believed that in the case of dyes, the dense cetyl shell can isolate the PEI from the bulky water and thus suppress the competitive binding by water; while in the case of surfactants, the semiclosed cetyl shell can simultaneously meet electrostatic complement and hydrophobic complement to the surfactants.