Constrained by low energy efficiency and ineffectiveness in As­(III) removal under circumneutral pH conditions by many exsiting technologies, As­(III) removal has become an issue. In this work we present proof of concept of a modified double potential step chronoamperometry (DPSC) method of As­(III) oxidation and concomitant As­(V) electro-sorption from aqueous solution. Results show that in situ anodic As­(III) oxidation, As­(V) electro-sorption, and As­(V) electro-desorption are affected by aqueous pH with high oxidation and sorption/desorption rates observed at the elevated pH. We particularly show that effective As­(III) oxidation and concomitant As­(V) adsorption are related to (i) the rapid oxidation of the deprotonated species compared to the protonated species and (ii) stronger electrochemical interaction between the multicharged As­(V) species and the electrodes. At 1.2 V and an electric energy consumption of 0.06 kWh m–3, the total As concentration can be reduced from 150 to 15 μg L–1 using an electrochemical cell with electrode area of 10 × 8 cm2 and electro-sorption time of 120 min. On the basis of the experimental results, we have developed a mathematical model to describe the kinetics and mechanism of arsenic removal by the modified DPSC method with this model of use in predicting, and potentially optimizing, process performance under various conditions.

In this work, we investigate selective sorption of arsenic from simulated groundwaters at pH 8 by a redox-active polyvinylferrocene (PVF)-functionalized electrode using a modified double potential step chronoamperometry (DPSC) method. Our results show that effective and sustainable As­(III) removal can be achieved at 0 V once the electrode is activated via anodic polarization. During activation, ferrocene (Fc) in PVF is oxidized to the ferrocenium ion (Fc+) with the latter facilitating As­(III) sorption and subsequent oxidation as well as As­(V) sorption. The high affinity of Fc+ to As and weak attraction to competing anions at 0 V ensure high selectivity of As over Cl–, SO4 2–, and NO3 – at concentrations typical of groundwaters. Following the removal process, efficient regeneration of the electrode is achieved at −1.2 V wherein Fc+ is reduced to Fc thereby facilitating As desorption from the electrode surface. Our results further show that O2 and associated generation of hydrogen peroxide during the regeneration step drive the oxidation of Fc to Fc+, thereby maintaining the constant generation of Fc+ required to achieve As­(III) removal in subsequent cycles. Our results show that 91.8 ± 0.6% of As­(III) could be selectively removed from simulated groundwater over 10 cycles at an ultralow energy consumption of 0.12 kWh m–3.

Boron is present in the form of boric acid (B­(OH)3 or H3BO3) in seawater, geothermal waters, and some industrial wastewaters but is toxic at elevated concentrations to both plants and humans. Effective removal of boron from solutions at circumneutral pH by existing technologies such as reverse osmosis is constrained by high energy consumption and low removal efficiency. In this work, we present an asymmetric, membrane-containing flow-by electrosorption system for boron removal. Upon charging, the catholyte pH rapidly increases to above ∼10.7 as a result of water electrolysis and other Faradaic reactions with resultant deprotonation of boric acid to form B­(OH)4 – and subsequent removal from solution by electrosorption to the anode. Results also show that the asymmetric flow-by electrosorption system is capable of treating feed streams with high concentrations of boron and RO permeate containing multiple competing ionic species. On the basis of the experimental results obtained, a mathematical model has been developed that adequately describes the kinetics and mechanism of boron removal by the asymmetric electrosorption system. Overall, this study not only provides new insights into boron removal mechanisms by electrosorption but also opens up a new pathway to eliminate amphoteric pollutants from contaminated source waters.

In this work, a starch imprinted magnetic nanoparticles composite material has been successfully synthesized. This molecular imprinted material has promising practical utility in capturing polysaccharides for pharmacology applications. First, we synthesized Fe3O4 nanoparticles by coprecipitation, followed by the modification of tetraethyl orthosilicate (TEOS) and functional amino group and aldehyde group, respectively. Then we used functionalized Fe3O4@SiO2 as the magnetic cores, starch as the template, 3-aminophenylboronic acid (APBA) as the functional monomer and ammonium persulphate (APS) as the initiator. Magnetic molecularly imprinted nanoparticles (MMIPs) were synthesized by surface-imprinted polymerization under airtight tubes at room temperature for 24 h. MMIPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) analysis. This showed a high saturation magnetization value (5.59 emu g(-1)) easily reached under an external magnetic field. The binding experiments were shown to have relatively high adsorption capacity (15.45 mg g(-1)) and selective recognition ability over structurally related compounds. Therefore, MMIPs provide a sensitive and selective approach and offer the potential to become a new key for polysaccharide separation and purification.

This paper presents an optimization study of inlet temperature of methanol synthesis reactor of LURGI type by using commercial simulator Aspen Plus and Aspen Energy Analyzer. The optimization routine is coupled to a steady-state model of the methanol synthesis reactor. By investigating the influences on methanol production and heat exchanger network synthesis, the inlet temperature of the reactor is optimized. when the inlet temperature is 230°C, the economic benefits of the methanol plant is maximized which could be increased by $ 44883.28/ year.