Biomimetic fat cell (BFC) modification and for lindane removal from aqueous solution

Abstract

To improve the regeneration ability of biomimetic fat cell (BFC), an innovative agent for hydrophobic organic contaminants (HOCs) removal, BFC was modified through introducing 1, 3, 5-benzenetricarboxyl trichloride with trifunctional group and heterocyclic piperazine in this research. Modified biomimetic fat cell (MBFC) has a good lindane removal capacity close to that of BFC and powder activated carbon (PAC), and the lindane removal is 97.68, 96.65 and 98.36% with 7 mg/L lindane initial concentration, respectively. At the same time, 20 mg/L MBFC or PAC is sufficient for 10 μg/L lindane removal, and in 20–60 mg/L doses range the lindane removal by both MBFC and PAC can reach 99.0%; When the doses is below 10 mg/L, MBFC showed better lindane removal than PAC and MBFC even could reach 96.8% lindane removal in 5 mg/L dose. Lindane removal by MBFC could be held on 95% above in first 6-time reuse. Though the lindane removal by MBFC decreased with the reuse time increasing, MBFC still could remove 80 % lindane after 9 times regeneration. In contract with BFC, MBFC showed obvious advantage on the regeneration. The lindane removal mechanism by MBFC, similar with BFC, includes bioaccumulation by MBFC nucleolus-triolein and adsorption by MBFC membrane, and the bioaccumulation is the main way.

Introduction

Adsorption, especially the activated carbon adsorption, has been proved to be one of the most important techniques for hydrophobic organic contaminants (HOCs) removal in aqueous environment, but the high cost of activated carbon and regeneration difficulty limits its use. Thus, alternative adsorbents with low cost, such as bagasse fly ash [1], [2], [3], [4], bottom ash [5], [6], red mud [7], [8], carbon columns obtained from fertilizer waste material [9] and so on, for the removal HOCs have been tried widely. A review about low-cost adsorbents could be found at the chapter “adsorbents for water treatment: low cost alternatives to carbon” of book “Encyclopedia of surface and collide science” [10].

Based on the fact that fat tissue of organism could accumulate hydrophobic chemicals and the accumulation level has the positive correlation with fat quantity [11], [12], [13], [14], an innovative agent, i.e., biomimetic fat cell (BFC) has been synthesized employing with interfacial polymerization. BFC has hydrophobic nucleolus-triolein and hydrophilic membrane-polyamide, the water carrying with the HOCs can pass through the polyamide membrane, and then the HOC_S will be accumulated by the triolein. BFC has 97.39% lindane (7 mg/L) removal ability close to 98.12% lindane removal by powder active carbon (PAC) in aqueous solution, but its regeneration is limited for its linear structure [15].

BFC regeneration mainly depends on the appropriate pore size of BFC membrane, which should be between the size of lindane and triolein. When organic solvent is used to dialyse lindane, lindane and triolein both can be dissolved into organic solvent, if the BFC membrane pore only permits lindane out of BFC with organic solvent, but stopping triolein, the BFC regeneration will be accepted.

The characteristics of polymer such as pore size result from how the chains are linked together in space. Symmetrical monomers such as terephthaloyldichloride and 1, 6-hexanediamineas can join together in only one way to form regular linear structure, while unsymmetrical multifunctional monomers such as 1, 3, 5-benzenetricarboxyl trichloride, terephthaloyldichloride could join piperazine together in random to form networked structure. With the increasing of cross-linkage, the pore size will become smaller and the density and rigidity of polymer will also improve [16].

The object of this research is to improve the regeneration ability of BFC through changing BFC membrane from linear structure to networked structure. Lindane was also selected to evaluate the HOCs removal capacity by modified biomimetic fat cell (MBFC) as selected in BFC preparation [15].