Highly enhanced adsorption of Congo red by functionalized finger-citron-leaf-based porous carbon.

A novel high-performance porous carbon material, lanthanum(III)-doped finger-citron-leaf-based porous carbon (La/FPC), has been synthesized and used as an adsorbent for anion dye Congo red (CR). The La/FPC was characterized by nitrogen adsorption and desorption isotherms, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The adsorption performance of CR by the FPC and La/FPC composites with different contents of lanthanum(III) were evaluated in fixed-bed breakthrough experiments and batch tests at room temperature (298 K). The La/FPC had a high CR uptake capacity, which was superior to those previously reported for other adsorbents. The La/FPC sorbents can be easily regenerated using an ethanol elution technique, and after five cycles the reused La/FPC maintained about 98% of its original CR adsorption capacity. The adsorption kinetics of CR onto the lanthanum(III)-doped FPCs followed a pseudo-second-order kinetic model and fitted well with a Langmuir adsorption isotherm. La/FPC is a promising adsorbent for the removal of the anionic dyes from wastewater.

[Complex enzyme combined with ultrasound extraction technology, physicochemical properties and antioxidant activity of Hedysarum polysaccharides].

In this study, complex enzymes combined with ultrasonic extraction technology（MC） were used, to select optimal extraction combinations by single factor and orthogonal test, with Hedysarum polysaccharides yield and content as the comprehensive indexes. The components, physicochemical properties and antioxidant activity of Hedysarum polysaccharides from complex enzyme combined with ultrasonic extraction（HPS-MC）and the Hedysarum polysaccharides from hot water extraction（HPS-R）were analyzed. The results showed that：complex enzymes had significant effect on the yield and content of Hedysarum polysaccharides, and the ultrasonic power could significantly improve the content of Hedysarum polysaccharides. The optimum technological parameters were as follows: complex enzyme ratio 1:1, ultrasonic power 105 W, ultrasonic time 60 min, and enzymatic hydrolysis pH 5, achieving （14.01±0.64）% and （92.45±1.47）% respectively for the yield and content of Polysaccharides. As compared with HPS-R, the molecular weight, absolute viscosity and protein content of HPS-MC were decreased, while the content of uronic acid was increased. In the antioxidant system, the concentration of polysaccharide was within the range of 1-7 g·L⁻¹; the antioxidant activity of HPS-MC was higher than that of HPS-R, and HPS-MC (80%) with the lowest molecular weight showed a significant dose effect relationship with the increase of the experimental concentration. In conclusion, MC is a simple, convenient, economical and environmentally friendly extraction technology, and the Hedysarum polysaccharides extracted by this method have obvious antioxidant activity.

Recovery of surfactant SDS and Cd2+ from permeate in MEUF using a continuous foam fractionator.

The purpose of this study was to investigate the use of foam fractionation to recover valuable surfactant (SDS) and metal ion (Cd2+) in the permeate of micellar-enhanced ultrafiltration (MEUF). The effects of operating factors, such as time, air flow rate, feed flow rate, liquid height, foam height, feed surfactant concentration, ethanol concentration and temperature on separation characteristics were studied in the continuous operation. When the concentrations of surfactant (SDS) and metal ion (Cd2+) in the feed solution were 500 mg/L and 10 mg/L, an enrichment ratio of 3.1 was achieved for SDS along with 52% removal fraction, as well as 99.35% Cd2+ was removed, after optimization of different process parameters. As the optimized results, the air and liquid flow rates were 100 L/h and 5 L/h, liquid and foam heights were 45 cm and 66 cm, respectively, sparger pore size was 10 microm. The Cd2+ concentration in the effluent was lower than 0.1mg/L which could meet the integrated wastewater discharge standard (the first grade of national discharge standards in China).

[Comparison for removing Cu2+ by micellar-enhanced ultrafiltration with SDS and SDBS].

Micellar-enhanced ultrafiltration was used to remove Cu2+ (Cu2+ was fixed at 0.6 mmol/L) from simulant aqueous solutions with SDS and SDBS as anionic surfactants respectively. Compare SDS and SDBS separation through permeate flux, permeate concentration, rejection and enrichment ratio. Experimental results show that the average permeate flux with SDS is always higher than that with SDBS [the average flux with SDS is 29.92 L x (m2 x h)(-1), while that with SDBS is only 16.55 L x (m2 x h)(-1)], the permeate concentration of SDS is always lower than that with SDBS. When the permeate concentration of Cu2+ close to zero, 2 mmol/L and 6 mmol/L of SDBS and SDS are respectively required. Cu2+ rejection and enrichment ratio with SDS are always higher than those with SDBS (the average Cu2+ rejection and enrichment ratio with SDS are respectively 85.06% and 4.18, while those with SDBS are 69.05% and 4.05 respectively). Besides, the average enrichment ratio of SDS is also higher than that of SDBS (SDS is up to 3.89, while SDBS is 3.13). Therefore, SDS is more suitable than the SDBS for removal of Cu2+.

Effect of groups difference in surfactant on solubilization of aqueous phenol using MEUF.

Micellar-enhanced ultrafiltration (MEUF) was used to remove phenol from simulant aqueous solutions. The effect of groups difference of cationic surfactant on the solubilization of phenol was investigated through orthogonal experiment, namely, surfactants with the same length of hydrocarbon chain but different hydrophilic head group and vice versa. The effects on the solubilization of phenol of various operating parameters in the practical application of MEUF with OTAB were studied, including surfactant concentration, electrolyte concentration, feed phenol concentration, operating pressure, temperature, respectively. The results showed that the rejection of phenol increased in the order as follows: cetyltrimethylammonium bromide (CTAB)

[Recovery and reuse of SDS by ultrafiltration with acid or chelator].

The retentate stream containing Cd2+ was chosen for the investigation. Effects of acid reagent, chelator, pH and operation mode on separation of Cd2+ and recovery of SDS, as well as efficiency of reclaimed SDS were investigated. The optimum conditions in acidification were obtained: H2SO4 as acid reagent, pH = 1.0, operation mode of batch. Under these conditions, separation of Cd2+ and recovery of SDS are 98.0% and 58.1%, respectively. And the efficiency of reclaimed SDS for removing Cd2+ is 80.2%. In chelation, the optimum conditions were investigated: EDTA as chelator, uncontrolled pH (pH = 4.4) and operation mode of batch. Under these conditions, separation of Cd2+ and recovery of SDS are 90.1% and 60.5%, respectively. And the efficiency of reclaimed SDS for removing Cd2+ is 79.4%.

[Recovery of Cd2+ by an electrolytic process from the concentrated solution of micellar enhanced ultrafiltration].

Micellar enhanced ultrafiltration (MEUF) is a new method which is based on the surfactant of the unique characteristic of parental molecular structure that can remove heavy metals in the water. The concentrated solution by dealing with the MEUF contains high concentration of heavy metal ions, so it must be need for further processing. The electrolysis method was employed to recovery Cd2+ from the concentrated solution of micellar enhanced ultrafiltration (MEUF). Effects of type of electrode, electrolysis voltage (U) and time (t), solution pH, surfactant to Cd2+ molar ratio ([SDS]/[Cd2+]) on Cd2+ recovery efficiency were investigated. The study found that the surfactant had some effect of resistance to electrolysis process. The optimum experimental conditions were obtained: stainless steel (anode)-graphite (cathode), U = 2.8 V, t = 100 min, pH = 4, [SDS]/[Cd2+] = 5 ([SDS] = 8.5 mmol/L constant). And the recovery efficiency of Cd2+ in the concentrated solution was 50.26%.

[Removal of metal ions and dissolved organic compounds in the aqueous solution via micellar enhanced ultrafiltration].

With continuing stringent environmental regulation, the traditional techniques are incapable of reducing the concentration of dissolved organics and heavy metals to the levels required by law or prohibitively expensive. Surfactant-based separation process such as micellar-enhanced ultrafiltration has been extensively proposed. Micellar-enhanced ultrafiltration has been demonstrated to be effective in removal of heavy metals and/or organic contaminants from wastewater stream. The process can be low energy cost and easily included in a whole process. Micellar-enhanced ultrafiltration has been shown to be a promising method for the removal of low-levelsof heavy metal ions and organic compounds from industrial effluents. This paper introduces the working mechanism, main factors of MEUF and the selection of surfactant and membrane. The lasted study progress on the application of micellar-enhanced ultrafiltration is reviewed. The recovery and reuse of surfactant from the retentate and permeate are also discussed.