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Abstract In this study, crude cellulose derived from cornstalk, after bleaching, was used as raw material for the synthesis of sodium carboxymethyl cellulose (CMC) by reacting with the cellulose with NaOH and chloroacetic acid at 75 °C for 1.5 h. Effects of alkali dosage, concentration of chloroacetic acid on the physical and chemical properties of the CMC products were investigated. It was revealed that the reactants alkali reagent/chloroacetic acid/cellulose at the molar ratio of 4.6:2.8:1and 4:2.5:1, or at the molar ratio of NaOH/ClCH 2 COOH ≈1.6–1.64, resulted in CMC products of relatively high water solubility. The viscosity-average molecular weight M v of these two CMC products obtained at molar ratios of 4.0:2.5:1 and 4.6:2.8:1 is in the range of 1.94 × 10 4 –2.48 × 10 4 g mol −1 , and the average DS of the two products are 0.57 and 0.85, respectively. As the solute concentration is above 2 wt%, the viscosity of the CMC-water solution exhibits nonlinear (exponential) increasing with increasing the solute concentration (typical of non-Newton fluids).

The microbial electrolysis desalination and chemical-production cell (MEDCC) is a device to desalinate seawater, and produce acid and alkali. The objective of this study was to enhance the desalination and chemical-production performance of the MEDCC using two types of stack structure. Experiments were conducted with different membrane spacings, numbers of desalination chambers and applied voltages. Results showed that the stack construction in the MEDCC enhanced the desalination and chemical-production rates. The maximal desalination rate of 0.58 ± 0.02 mmol/h, which was 43% higher than that in the MEDCC, was achieved in the four-desalination-chamber MEDCC with the AEM-CEM stack structure and the membrane spacing of 1.5mm. The maximal acid- and alkali-production rates of 0.079 ± 0.006 and 0.13 ± 0.02 mmol/h, which were 46% and 8% higher than that in the MEDCC, respectively, were achieved in the two-desalination-chamber MEDCC with the BPM-AEM-CEM stack structure and the membrane spacing of 3mm.

Abstract Economically harvesting energy from a microbial fuel cell (MFC), increasing its electrical power production, and developing its role as a practical energy supply, needs a low-cost and high-performance design of the MFC compartments. According to this strategy, a novel monolithic membrane electrode assembly (MEA) was fabricated and evaluated as an air–cathode in a single-chamber MFC (SCMFC). The MEA was made of bacterial cellulose (BC), conductive multi-walled carbon nanotubes (CNT), and nano-zycosil (NZ). BC, as a nano-celluloses with oxygen barrier property, can maintain anaerobic conditions for the anode compartment. Binder-less CNT coating on BC avoids costly binders such as poly-tetra fluoro ethylene (PTFE) and Nafion and decreases the MEA charge transfer resistance. NZ, as a very cheap modifier, not only prevents the anolyte leakage but also provides more MEA’s active sites for the oxygen reduction reaction (ORR). The electrochemical performance of the MEA was compared to a PTFE- based gas diffusion electrode (GDE) in the SCMFC. The MEA cell provided a pulse power density of 1790 mW/m2, roughly twice as high as the pulse power density of GDE (920 mW/m2). SCMFC’s internal resistance decreased from 1.84 KΩ (with GDE) to 0.8 KΩ (with MEA). Also, the cell’s columbic efficiency increased from 4.2% (with GDE) to11.7% (with MEA). Additionally, the capacitance of the MEA (65 mF) was much higher than the value for GDE (0.73 mF). Thus, the MEA compared to the GDE showed higher performance in the SCMFC for electricity generation and wastewater treatment at a lower cost.

Anode with good electrocatalytic capabilities is more specifically required to reduce the ohimic losses during microbial fuel cell (MFC) operation. Highly conductive polymers viz., Polyaniline (PANi) and Polyaniline/Carbon nanotube (PANi/CNT) composite were prepared by in situ oxidative chemical polymerization method. Anodes were fabricated independently by coating PANi and CNT/PANi composites on the surface of SSM. The fabricated electrodes were evaluated as anode against stainless steel mess (SSM) as cathode during MFC operation. Maximum bioelectricity generation was observed in SSM-PANi/CNT-anode with power density of 48 mW/m2 and COD removal efficiency of 80% compared with SSM-PANi-anode (38 mW/m2; 65%) and SSM-anode (28 mW/m2; 58%). Bioelectrochemical characterization of the electrode materials using cyclic voltammetry and electrochemical impedance spectroscopy showed high electrocatalytic activity of PANi/CNT composite electrode. The study concluded the efficiency of PANi/CNT composite electrodes as bioanode in operation of MFCs towards achieving increased bioelectricity production along with wastewater treatment.

Abstract Dried and grated biological waste was immobilized with cement to generate specimens mimicking solidified phytoremediated radioactive waste. Stability of these solidified biological waste specimens was estimated during drastic long-term flooding, which is considered one of the typical environmental impacts affecting physical and mechanical characteristics of such specimens. For these investigations, biological waste generated during phytoremediation using the aquatic plant Veronica anagallis-aquatica was solidified and subsequently examined during flooding. After flooding with water of different compositions, mechanical and physical stability of the specimens was evaluated. Cementation of 3% dried biological waste resulted in a satisfying compressive strength of the resulting solidified material of more than 13 MPa. The highest value of hardness exceeded 25 MPa, and was obtained in samples cured in sea water or ground water due to mineral salts sealing the pores, whereas an insignificant decrease in durability was observed in those specimens cured in tap water. Maximum mass change caused by the water absorption during six months of curing was below 4.5% of the initial mass; this change was more pronounced for solidified waste immersed in sea water or ground water than for samples immersed in tap water. Retardation of material and status of the cement phases after flooding were investigated via FT-IR, XRD and SEM; the results point to the suitability of this cement type as powerful material for immobilization of biological radioactive waste, as manifested by acceptable durability and reasonable porosity during long immersion in different water compositions.

AbstractToday, the issue of reducing industrial pollution has received much attention. The textile industry is of high important throughout the world. However, its by‐product wastewater pollutes the environment. The first approach was the selection of plant‐based dyes (madder and reseda) and the application of tannin‐based mordants (pomegranate peel and myrobalan). The extraction of madder, reseda, and pomegranate peel in water with the ultrasound‐assisted method was done. In this article, pre‐mordanting method was used for mordanting and Cu (copper) and alum were selected as the mineral mordant to compare the results. Fourier Transform Infrared Spectroscopy method was employed to analyze the obtained extracts and to investigate the changes in the fibers. The results showed that K/S (color strength) values of the dyed samples increased by increasing the dye concentration. The colorfastness properties of the samples were investigated according the ISO standards.

Reverse electrodialysis (RED) is a technology to generate power from mixing waters with different salinity. The net power density (i.e. power per membrane area) is determined by 1) the membrane potential, 2) the ohmic resistance, 3) the resistance due to changing bulk concentrations, 4) the boundary layer resistance and 5) the power required to pump the feed water. Previous power density estimations often neglected the latter three terms. This paper provides a set of analytical equations to estimate the net power density obtainable from RED stacks with spacers and RED stacks with profiled membranes. With the current technology, the obtained maximum net power density is calculated at 2.7 W/m2. Higher power densities could be obtained by changing the cell design, in particular the membrane resistance and the cell length. Changing these parameters one and two orders of magnitude respectively, the calculated net power density is close to 20 W/m2

Abstract The release of carbon dioxide from fossil fuel combustion into the atmosphere is one of the leading causes of global climate change. The existing technologies for the capture of CO2 suffer from various drawbacks creating an opportunity for the development of new technologies. In this investigation, sodium-based sorbents were prepared and evaluated for performance in CO2 sorption. A series of Na2CO3-based sorbents was coated onto metal foils. The loading of Na2CO3 was maintained in the range of 25–40 wt.% on Al2O3. The performance of these sorbents was tested in a fixed-bed reactor at various absorption temperatures and at various water concentrations. To compare the performance of the sorbent coated metal foils, a series of Na2CO3/Al2O3 powder sorbents was also prepared by impregnation method with the same concentration of Na2CO3 as in the case of foil samples. In general, sorbent powders showed better performance compared to those of foil samples, but 35% Na2CO3/Al2O3 sorbent coated on foil showed highest performance (∼7.7 mol of CO2/kg of Na2CO3). This sorbent was also investigated for 500 cycles to evaluate the stability of the sorbent.

Correction for ‘Mesoporous thin film WO3 photoanode for photoelectrochemical water splitting: a sol–gel dip coating approach’ by Samantha Hilliard et al., Sustainable Energy Fuels, 2017, 1, 145–153.