No abstract

A new inorganic-organic composite dual-coagulant (PAFC-CPAM) was prepared by polyaluminum ferric chloride (PAFC) and cationic polyacrylamide (CPAM) and its treatment efficiency for oily wastewater was evaluated by coagulation jar tests. PAFC-CPAM dual-coagulants were characterized by FT-infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The FTIR spectra illustrated that there were some chemical reactions between PAFC and CPAM in PAFC-CPAM. SEM micrographs testified that PAFC-CPAM formed compact net structure which is different from PAFC and CPAM, resulting to its outstanding coagulation performance other than monomeric coagulant in treating oily wastewater. Coagulation jar tests presented that PAFC-CPAM improved 1.14% and 0.38% of oil removal rate and reduced 0.35NTU and 0.06NTU of residual turbidity than PAFC and CPAM respectively at the optimal dosage of 120mg/L. PAFC-CPAM enhanced 4.56% and 2.12% of oil removal efficiency and decreased 0.27NTU and 0.01NTU of residual turbidity on average in comparison with PAFC and CPAM respectively in the pH range of 4.0-8.0. All of above-mentioned experiment results demonstrated that PAFC-CPAM behaved superior coagulation performance than PAFC and CPAM.

Modified bamboo-charcoal (MBC) was prepared by Ferric sulfate dipping and microwave radiation with 20～30 mesh bamboo-charcoal (BC) pretreated by water boiling as the support. The original and modified BC were characterized by SEM, FTIR, XRD, BET and BJH. Fluoride removal from simulated drinking water containing fluoride was probed into with MBC. The results indicated that MBC took on minor average pore diameter (1.172nm), major microspores and greater specific surface area (99.891 m2/g). Loaded iron combined with BC by bonds from BC such as H-O-H bond, C-O bond and O-H bond. The increase of fluoride removal after BC being modified suggests that MBC is a more potential defluorinate agent.

The effect of operating conditions, such as adsorption time, adsorbent dosage, influent pH and influent oil concentration, on the performance of organic modified sepiolite used for the treatment of steel rolling oily wastewater was investigated via single factor method, and the adsorption kinetics and thermodynamics were also studied with batch test. Results indicated that oil removal rate reached 96.78% in 45 min which increased by 55.44% compared with crude sepiolite. Reasons for oil removal efficiency rise with organic modified sepiolite included augmentation of interlayer distance (0.007 nm larger than crude sepiolite), increase of specific surface area (from 41.63 to 104.40 m2/g) and stronger hydrophobic. The pseudo second order kinetic model well described experiment data with a perfect correlation coefficient value of 0.9999. Thermodynamic parameters including the Gibbs free energy (△G0), enthalpy (△H0), and entropy (△S0) revealed that adsorption process was a spontaneous, exothermic and physical adsorption process. <b></b>

Based on the pretreatment including acidification, purification and sodium ion exchange, the crude sepiolite was modified by microwave radiation-wet process and CTAB as modifier. The orthogonal experiment was used to optimize the modification process. Then the crude sepiolite and modified sepiolite were characterized by SEM, FTIR, XRD, TG-DSC and BET. The results showed that the optimum modification process parameters included CTAB dosage (1.0 cation exchange capacity (CEC)), microwave radiation time (4 minutes), ethanol concentration (50%/V:V) and radiation power (800W). Compared with crude sepiolite, oil removal rate from steel rolling wastewater increased from 41.34% to 96.78% with modified sepiolite prepared at the best process. Characteristic peaks of organic functional groups, enlarged interlayer distance (0.007nm larger than crude sepiolite), enhanced hydrophobicity, amplified specific surface area (104.4m2/g) and mesopore volume had been received from above characterization methods after modification. All of the above had proved that CTAB was successfully grafted onto sepiolite.