Preparation of bright yellow color sodium alginate solution.

Sodium alginate (SA) is a marine polysaccharide biomass material that is environmentally friendly and exhibits color-changing properties under certain conditions. In this study, we have discovered sodium alginate solution to be chromogenic under four conditions, namely alkali-chromogenic, thermo-chromogenic, force-chromogenic and photo-chromogenic. Under simple strong alkaline conditions, sodium alginate forms clusters of blue light-absorbing chromogenic aggregates, which exhibit a bright yellow color at a certain size. Under different temperature conditions, SA shows varying shades of yellow, and the color tends to stabilize after 48 h of resting. The aggregates can be dispersed by stirring, which changes SA from yellow to colorless. The yellow color can then be recovered after resting. Additionally, exposure to sunlight can cause the yellow SA to fade, but the color can be restored by reheating. Therefore, the force-chromogenic and photo-chromogenic properties are reversible. This makes it a promising material for use in color-developing and indicating materials. It is expected to become a sodium alginate cluster pigment with broad application prospects in the future.

Green electrospun Janus membrane of polyether block amide (PEBA) doped with hierarchical magnesium hydrogen phosphate for the removal of pharmaceuticals and personal care products.

It has been a challenge to prepared polyether block amide (PEBA) fibrous membrane via solution electrospinning. The only few reported methods though involved hazardous solvents and surfactants which were against the principle of green chemistry. In this work, uniform fibrous membrane of PEBA was successfully fabricated by solution electrospinning with a bio-based solvent dihydrolevoglucosenone (Cyrene). To further improve the mechanical strength and adsorption performance of the PEBA membrane, a hierarchical magnesium hydrogen phosphate (MgHPO4·1.2H2O, MHP) was synthesized to blend evenly into the PEBA matrix. A Janus MHP/PEBA membrane with one side of hydrophobic surface and the other side of hydrophilic surface was subsequently prepared, which exhibited fast adsorption, high capacity, good selectivity and reusability towards ibuprofen, acetaminophen, carbamazepine and triclosan. In addition, the Janus membrane showed high removal efficiency of the above contaminants in secondary wastewater effluent with good long term stability. It demonstrated that this Janus MHP/PEBA membrane had a good potential in practical wastewater treatment.

Electrospun nanofibrous poly(ether-block-amide) membrane for removing biogenic amines in acidic wastewater from the yellow rice wine factory.

Compared with other techniques for wastewater treatment, adsorption offers an effective, economical and ecofriendly way to reduce the content of biogenic amines. Herein, the poly(ether-block-amide) (PEBA 2533) membranes were employed as the adsorbent to remove histamine, putrescine, cadaverine and tyramine in the synthetic and real wastewater from a local yellow rice wine factory. Electrospun PEBA membranes consisting of fine nanofibers were successfully obtained without the addition of surfactant for the first time. Characteristics of the prepared membranes were evaluated by their morphology, wetting behaviors and mechanical properties. Adsorption performance of the nanofibrous membrane was investigated in comparison to the dense membrane prepared by conventional casting. The fibrous membrane exhibited much higher adsorption rate over 10 times to the dense membrane along with 1.5 times more adsorption capacity towards the amines. In addition, the as-prepared membrane showed a promising reusability in the real wastewater treatment. The good balance of its chemical stability, adsorption capacity, selectivity, removal efficiency and reusability endows the electrospun membrane with an outstanding potential to be applied in the acidic wastewater treatment for the yellow rice wine industry.

An antifouling gel-protected iridium needle sensor: Long-term, on-site monitoring of copper in seawater.

Copper (Cu), a natural micronutrient with ecotoxicological significance, is involved in the carbon and nitrogen cycles occurring in marine ecosystems. Here, we developed a novel, antifouling gel-protected iridium (Ir) needle electrode modified with gold nanoparticles (G-IrNS) for long-term continuous and steady Cu monitoring. The gel formed an efficient membrane that effectively prevented the fouling of the sensing surface and displayed anti-convective properties, ensuring that mass transport toward the sensor surface was wholly controlled via diffusion. The repeatability, reproducibility, and stability of G-IrNS showed that it was suitable for long-term and on-site monitoring of Cu in seawater. Cu concentrations were successfully measured via fixed-point continuous monitoring for >2 weeks and onboard continuous monitoring in Bohai Sea using one sensor. Moreover, the relationship between Cu concentrations measured on-site via G-IrNS and its dissolved concentration in Bohai Sea was evaluated. G-IrNS can be applied to other metal ions as well, especially for long-term automatic on-site monitoring, thereby providing a basis for further research.

Preparation of polyethersulfone/magnesium silicate membranes via casting and electrospinning and their application in the removal of free fatty acids from biodiesel.

Due to the reversible nature of reactions in biodiesel production, a purification process is necessary for the biodiesel to meet international standards. As an effective method, dry washing has been applied in biodiesel purification for years, but it still faces limitations and challenges. In this work, a magnesium silicate (MS) was synthesized using the hydrothermal method. Two types of composite membranes were prepared by doping the prepared magnesium silicate into polyethersulfone (PES) via casting and electrospinning, respectively. Structural and physical properties of the composite membranes were characterized. The composite membranes were applied as adsorbents to remove free fatty acids (FFAs) from crude biodiesel. Adsorption isotherm and kinetic studies were performed at different temperatures (20, 40 and 60 °C). For both membranes, the obtained adsorption capacity was higher at low temperature (20 °C). Maximum adsorption capacity was found with the electrospun membrane to be 852 mg g-1, calculated from the Langmuir model. Adsorption kinetics for both membranes can be well described using the pseudo-second-order model. In addition, the internal diffusion was not negligible during the adsorption process based on the intraparticle diffusion analysis. As revealed by thermodynamic study, the adsorption processes were all exothermic with a spontaneous nature. Reusability of the membrane adsorbents was evaluated, in which the electrospun membrane showed a promising performance with 94% adsorption capacity remaining over 8 cycles of adsorption and desorption.

Enhanced flux performance of polyamide composite membranes prepared via interfacial polymerization assisted with ethyl formate.

A novel thin film composite (TFC) polyamide reverse osmosis membrane was prepared via the interfacial polymerization of m-phenylene diamine (MPD) in aqueous phase and 1,3,5-trimesoyl chloride (TMC) in organic phase on a polysulfone ultrafiltration support by assisting with ethyl formate as a co-solvent added in the organic phase. The ethyl formate added in the organic phase is intended to form a narrow miscibility zone, which leads to the thicker reaction zone. The multi-layered loose polyamide structure with larger pore size was formed due to the thicker reaction zone and lower content of MPD. The enhanced hydrophilicity of the membrane was proved by the decreased water contact angle. Water flux was measured at 1.6 MPa with 2,000 ppm NaCl aqueous solution. Compared to the TFC membrane prepared without ethyl formate, the water flux across the TFC membrane with ethyl formate in the organic phase increased with the increased ethyl formate content (from 23 to 45 L/(m2 h)) and the salt rejection remained at a high level (>90%). The ethyl formate can be used as a co-solvent to effectively enhance the performance of the TFC membrane.

Preparation and Characterization of Mesoporous Magnesium Silicate Gels and Application for Cobalt(II) Removal.

Two new mesoporous magnesium silicate gel adsorbents, MgO x 2SiO2 and MgO x 6SiO2, have been successfully prepared by hydrothermal method. The synthetic factors including reaction pH, temperature, time and calcination temperature were studied. The aiming products were characterized by N2 adsorption/desorption isotherms, FT-IR spectroscopy and Scanning Electron Microscopy (SEM). The adsorption behaviors for cobalt ions were also systematically investigated. The results show that the reaction pH was the decisive factor for Si/Mg mole ratios. The special surface areas are 534.29 m2 x g(-1) for MgO x 2SiO2 and 181.61 m2 x g(-1) for MgO x 6SiO2, respectively. The maximum adsorption capacities of MgO x 2SiO2 and MgO x 6SiO2 for cobalt ions are 135.5 and 52.5 mg x g(-1). Furthermore, the experimental data are well described by pseudo-second order adsorption and Langmuir isotherm models. The experiment would afford one excellent adsorbent for solving the wastewater pollution and also providing metal cobalt for modern industry including new energy car.

[Removal of PO4(3-) from solution, wastewater and seawater by modification and granulation magnesium and aluminium layered double hydroxide].

Powder layered double hydroxide of Mg-Al LDH were prepared by hydrothermal technology with 500 kg x batch(-1), modified and granulated (MG Mg-Al CLDH) by deposition method. After the modification and granulation, the fixed bed can not be accumulated and clogged by the adsorbents. The PO4(3-) is removed from aqueous solution, wastewater and seawater by MG Mg-Al CLDH with column experiments. It shows that MG Mg-Al CLDH is an effective adsorbent. After removal, the water quality can satisfy with the first degree of integrated wastewater discharge or seawater standards. The mechanism of removal PO4(3-) is ion exchange and 'memory effect'. The breakthrough adsorption capacity of PO4(3-) from solution is 13.49 mg x g(-1), more than 6 times higher than that by Mg-Al LDH without modification. The exhausted MG Mg-Al CLDH can be desorbed with 0.1 mol x L(-1) NaOH and 3 mol x L(-1) NaCl and regenerated with 25% MgCl2. The regeneration rate is 126.24%. The breakthrough curves are influenced by bed depth, flow rate, initial concentration and initial pH. The adsorption processes are controlled by film diffusion. When the initial concentration is as low as 0.38 micromol x L(-1), PO4(3-) can be removed from seawater to satisfy with the first degree of seawater quality. So this work is very useful for the practical application of Mg-Al LDH and the removal of phosphorus.

[Adsorption properties of thiocyanate anion on granular Mg/Al mixed oxides].

Granular Mg/Al mixed oxides (G-Mg3.3 AlO4.8) was successfully synthesized by using Mg/Al layered double hydroxide (Mg/Al-LDH) as the precursor. Its structure was characterized by analytical methods of BET, XRD, SEM and FT-IR. Adsorption properties of thiocyanate anion (SCN-) on this new material were also investigated. Specific surface area and average pore width of G-Mg3.3 AlO4.8 are 269.4 m2 x g(-1) and 13.25 nm respectively. Molding and granulation retains the layer structure and generates no new phase. Freundlich isotherm equation and pseudo-second-order kinetic equation can describe the static adsorption process precisely and adsorption capacity reaches 165.8 mg x g(-1) at 25 degrees C and 500 mg x L(-1). Yoon-Nelson model can predict the breakthrough curves of SCN- on G-Mg3.3 AlO4.8 precisely. The breakthrough adsorption capacity reaches 50.73 mg x g(-1) under the conditions with initial concentration is 100 mg x L(-1), flow rate is 5 mL x min(-1), bed layer altitude is 10 cm and initial pH is 6. The removal rates of SCN- are all above 98% after reusing four times. Consequently, G-Mg3.3 AlO4. 8 is a reusable and high-efficient adsorbent.

[Comparison of the adsorption of arsenite and arsenate anions from aqueous solution by calcined Mg-Al layered double hydroxides].

The comparison of calcined Mg-Al layered double hydroxides (Mg-Al CLDH) for adsorption of arsenite and arsenate anions from aqueous solution was investigated by batch method. The results show that Mg-Al CLDH is an effective adsorbent for the removal of arsenite and arsenate anions. The adsorption processes are followed 'memory effect'. When the initial concentration of arsenic is lower than 10 mg x L(-1) for arsenite and 40 mg x L(-1) for arsenate, the equilibrium concentration of arsenic is lower than 10 microg x L(-1). In the range of 4-500 mg x L(-1) for initial arsenic concentration, the maximum adsorption capacity of arsenite and arsenate on Mg-Al CLDH from 298 to 323 K is 150.46-224.03 mg x g(-1) and 149.62-224.76 mg x g(-1), respectively, which are much larger than other adsorbents. But the adsorption capacity is not reached saturation, it is continued to increase significantly. L and H model can be used to describe the adsorption isotherm of arsenite and arsenate, respectively. The adsorption data are corresponded to the Freundlich model for arsenite and Langmuir model for arsenate at lower equilibrium concentration, but corresponded to Freundlich model for arsenite and arsenate at higher equilibrium concentration. Under the same temperature and initial concentration, the adsorption rate and removal rate of arsenate are higher than those of arsenite. And they are increased with temperate but decreased with increase in initial concentration. Adsorption processes follow the pseudo-second-order kinetic model for both arsenite and arsenate. The removal rate is not influenced by the initial pH (3.0-10.0). The adsorption capacity is influenced insignificantly by ionic strength. Arsenate anions are adsorbed firstly from arsenite and arsenate solution on Mg-Al CLDH.

Dimethyl-bis(3-methylsulfanyl-1,2,4-thia-diazole-5-thiol-ato)tin(IV).

In the title compound, [Sn(CH(3))(2)(C(3)H(3)N(2)S(3))(2)], the Sn(IV) atom is coordinated within a C(2)N(2)S(2) donor set that defines a skew-trapezoidal bipyramidal geometry in which the methyl groups lie over the weakly coordinated N atoms. Two independent mol-ecules comprise the asymmetric unit, each of which lies on a mirror plane that passes through the C(2)Sn unit.

catena-Poly[[(3-methyl-sulfanyl-1,2,4-thia-diazole-5-thiol-ato)sodium]di-µ-aqua-κO:O].

The crystal structure of the title compound, [Na(C(3)H(3)N(2)S(3))(H(2)O)(2)](n), features polymeric chains made up of O⋯O edge-shared NaSN(H(2)O)(4) units running along the b axis. The Na(+) ion and all non-H atoms of the thia-diazole ligand lie on a mirror plane.