Junlian Qiao

The removal of bisphenol A from aqueous solutions by MIL-53(Al) and mesostructured MIL-53(Al).

In this work, metal-organic framework MIL-53(Al){Al(OH)[O2C-C6H4-CO2]} and MIL-53(Al)-F127{Al(OH)[O2C-C6H4-CO2]} were synthesized and used as sorbents to remove bisphenol A (BPA) from aqueous system. The sorption kinetics data of BPA were found to be in agreement with the pseudo-second-order model. The equilibrium sorption amounts of BPA on MIL-53(Al) and MIL-53(Al)-F127 reached 329.2±16.5 and 472.7±23.6 mg g(-1), respectively, far more than that of commercial activated carbons (ranging from 129.6 to 263.1 mg g(-1)). Both MIL-53(Al) and MIL-53(Al)-F127 could remove BPA fast from aqueous solutions, and the required contact time to reach equilibrium was approximately 90 min for MIL-53(Al) and 30 min for MIL-53(Al)-F127, respectively. The optimum pH levels for the removal of BPA using MIL-53 (Al) and MIL-53(Al)-F127 were 4 and 6 separately. The optimum temperature for the sorption behavior of BPA on the two sorbents was 20 °C. The results performed show that the resulting products, as one kind of MOFs, can be regarded as a new class of sorbents for water treatment and could find great applications in the fields of environmental water pollution control and resources reuse.

Preparation and application of amino functionalized mesoporous nanofiber membrane via electrospinning for adsorption of Cr3+ from aqueous solution

Novel amino (-NH2) functionalized mesoporous polyvinyl pyrrolidone (PVP)/SiO2 composite nanofiber membranes were fabricated by a one-step electrospinning method using poly (vinyl alcohol) and tetraethyl orthosilicate (TEOS) mixed with cationic surfactant, cetyltrimethyl ammonium bromide (CTAB) as the structure directing agent. Ureidopropyltriethoxysilane was used for functionalization of the internal pore surfaces. The membranes were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) images, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), element analyzer and N2 adsorption-desorption isotherms. The nanofiber diameters, average pore diameters and surface areas were 100-700 nm, 2.86 nm and 873.62 m2/g, respectively. These mesoporous membranes functionalized with -NH2 groups exhibited very high adsorptions properties based on the adsorption of Cr3+ from an aqueous solution. Equilibrium adsorption was achieved after approximately 20 min and more than 97% of chromium ions in the solution were removed. The membrane could be regenerated through acidification.

Pre-oxidation with KMnO4 changes extra-cellular organic matter's secretion characteristics to improve algal removal by coagulation with a low dosage of polyaluminium chloride

Microcystis aeruginosa was used to study the effect of KMnO4 pre-oxidation on algal removal through coagulation with polyaluminium chloride (PAC). KMnO4 pre-oxidation improved the coagulation efficiency of algal at a low dosage of PAC. The optimal KMnO4 feeding period was in the stationary growth phase of Microcystis aeruginosa. KMnO4 traumatized the algal cells and stimulated cellular release of organic matter, contributing to the pool of extra-cellular organic matter (EOM). KMnO4 also decomposed EOM, especially small molecular weight EOM. Lower concentrations of KMnO4, such as 2 mg/L, induced algae cells to produce moderate amounts of new EOM with molecular weights of 11, 280, and 1500 kDa. These relatively large molecules combined easily with PAC, promoting coagulation and removal of algae. High concentrations of KMnO4 lysed algae cells and produced much high-molecular-weight EOM that did not enhance flocculation by PAC at lower dosages.

Efficient degradation of lube oil by a mixed bacterial consortium

A laboratory study was performed to assess the biodegradation of lube oil in bio-reactor with 304# stainless steel as a biofilm carrier. Among 164 oil degrading bacterial cultures isolated from oil contaminated soil samples, Commaonas acidovorans Pxl, Bacillus sp. Px2, Pseudomonas sp. Px3 were selected to prepare a mixed consortium for the study based on the efficiency of lube oil utilization. The percentage of oil degraded by the mixed bacterial consortium decreased slightly from 99% to 97.2% as the concentration of lube oil was increased from 2000 to 10,000 mg/L. The degradation of TDOC (total dissolved organic carbon) showed a similar tendency compared with lube oil removal, which indicated that the intermediates in degradation process hardly accumulated. Selected mixed bacterial consortium showed their edge compared to activated sludge. Scanning electron microscopy (SEM) photos showed that biofilms on stainless steel were robust and with a dimensional framework constructed by EPS (extracellular polymeric substances), which could promote the biodegradation of hydrocarbons. The increase of biofilm followed first-order kinetics with rate of 0.216 microg glucose/(cm2-day) in logarithm phase. With analysis of Fourier transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) combined with removal of lube oil and TDOC, mixed bacterial consortium could degrade benzene and its derivatives, aromatic ring organic matters with a percentage over 97%.

Influence of Chemicals on Biofilm Removal in Cooling Water System

Microbial cells can attach onto the stainless steel surface in cooling water system and form biofilms which are harmful to the industrial equipments. In this study, biofilms formed on stainless steel with mixed bacterial were investigated by scanning electron microscopy (SEM) to discuss the biofilm transformation before and after treatment with chemicals. Oxidizing biocide (Tetrakishydroxymethyl phosphonium sulphate), non-oxidizing biocide (Sodium hypochlorite), and surfactant (sodium dodeccyl benzene sulfonate) were selected for biofilm treatment. SEM photos showed that the low-molecular weight biocide possessed penetration function and the oxidizing-biocide exhibited strong oxidation ability. Anionic surfactant could change the dimensional structure of biofilm and was helpful for further treatment.