Water reclamation from shale gas drilling flow-back fluid using a novel forward osmosis-vacuum membrane distillation hybrid system.

This study examined the performance of a novel hybrid system of forward osmosis (FO) combined with vacuum membrane distillation (VMD) for reclaiming water from shale gas drilling flow-back fluid (SGDF). In the hybrid FO-VMD system, water permeated through the FO membrane into a draw solution reservoir, and the VMD process was used for draw solute recovery and clean water production. Using a SGDF sample obtained from a drilling site in China, the hybrid system could achieve almost 90% water recovery. Quality of the reclaimed water was comparable to that of bottled water. In the hybrid FO-VMD system, FO functions as a pre-treatment step to remove most contaminants and constituents that may foul or scale the membrane distillation (MD) membrane, whereas MD produces high quality water. It is envisioned that the FO-VMD system can recover high quality water not only from SGDF but also other wastewaters with high salinity and complex compositions.

Disulfide-based PEGylated prodrugs: Reconversion kinetics, self-assembly and antitumor efficacy.

The prodrug strategy serves well in drug formulation and delivery. Two disulfide-based PEGylated prodrugs were developed and the drug reconversion upon different conditions were studied in detail. The reconversion-induced oversaturation phenomenon was firstly reported here. We found the prodrug can co-assemble with parent drug via π-π stacking into well-defined nanoparticles. The PEG layer of the self-assembled nanoparticles improved the stability of the PEGylated prodrug by reducing the contact with biological enzymes. The nanoparticles also show favorable antitumor efficacy, both in vitro and in vivo.

Composite hollow fiber nanofiltration membranes for recovery of glyphosate from saline wastewater.

A high performance versatile composite hollow fiber nanofiltration (NF) membrane is reported for the separation of glyphosate from saline waste streams. Preparation of SPEEK based on an amorphous poly (ether ether ketone, PEEK) was investigated. The membrane was prepared by coating sulfonated polyether ether ketone (SPEEK) onto a polyethersulfone (PES) ultrafiltration (UF) hollow fiber membrane. The composite membrane was characterized by water permeability, scanning electron microscopy, and rejection toward sodium sulfate (Na2SO4), sodium chloride (NaCl), and calcium chloride (CaCl2). About 90% rejection toward sulfate anions and only 10% rejection for calcium cations were obtained. A water permeability around 10-13 LMHBar and 90% rejection for polyethylene glycol (PEG) with a molecular weight of 4000-6000 Da were observed. In the separation of glyphosate from saline wastewater, the membrane rejected less than 20% of NaCl and higher than 90% of glyphosate at an operating pressure of 5 bars and pH = 11.0. An economic analysis indicated that the cost for recovery of glyphosate was comparably low to the value gained by an increase in the productivity. The results may lead to a new promising low energy solution for the environmental problem faced by the herbicide industry.