Graphitized mango seed as an effective 3D anode in batch and continuous mode microbial fuel cells for sustainable wastewater treatment and power generation.

Herein, we explored the utilization of graphitized mango seeds as 3D-packed anodes in microbial fuel cells (MFCs) powered by sewage wastewater. Mango seeds were graphitized at different temperatures (800 °C, 900 °C, 1000 °C, and 1100 °C) and their effectiveness as anodes was evaluated. Surface morphology analysis indicated that the proposed anode was characterized by layered branches and micro-sized deep holes, facilitating enhanced biofilm formation and microorganism attachment. Maximum power densities achieved in the MFCs utilizing the mango seed-packed anodes graphitized at 1100 °C and 1000 °C were 2170.8 ± 90 and 1350.6 ± 125 mW m-2, respectively. Furthermore, the weight of the graphitized seed anode demonstrated a positive correlation with the generated power density and cell potential. Specifically, MFCs fabricated with 9 g and 6 g anodes achieved maximum power densities of 2170.8 ± 90 and 1800.5 ± 40 mW m-2, respectively. A continuous mode air cathode MFC employing the proposed graphitized mango anode prepared at 1100 °C and operated at a flow rate of 2 L h-1 generated a stable current density of approximately 12 A m-2 after 15 hours of operation, maintaining its stability for 75 hours. Furthermore, a chemical oxygen demand (COD) removal efficiency of 85% was achieved in an assembled continuous mode MFC. Considering that the proposed MFC was driven by sewage wastewater without the addition of external microorganisms, atmospheric oxygen was used as the electron acceptor through an air cathode mode, agricultural biomass waste was employed for the preparation of the anode, and a higher power density was achieved (2170.8 mW m-2) compared to reported values; it is evident that the proposed graphitized mango seed anode exhibits high efficiency for application in MFCs.

Synergistic advancements in sewage-driven microbial fuel cells: novel carbon nanotube cathodes and biomass-derived anodes for efficient renewable energy generation and wastewater treatment.

Microbial fuel cells (MFCs) offer a dual solution of generating electrical energy from organic pollutants-laden wastewater while treating it. This study focuses on enhancing MFC performance through innovative electrode design. Three-dimensional (3D) anodes, created from corncobs and mango seeds via controlled graphitization, achieved remarkable power densities. The newly developed electrode configurations were evaluated within sewage wastewater-driven MFCs without the introduction of external microorganisms or prior treatment of the wastewater. At 1,000°C and 1,100°C graphitization temperatures, corncob and mango seed anodes produced 1,963 and 2,171 mW/m2, respectively, nearly 20 times higher than conventional carbon cloth and paper anodes. An advanced cathode composed of an activated carbon-carbon nanotube composite was introduced, rivaling expensive platinum-based cathodes. By optimizing the thermal treatment temperature and carbon nanotube content of the proposed cathode, comparable or superior performance to standard Pt/C commercial cathodes was achieved. Specifically, MFCs assembled with corncob anode with the proposed and standard Pt/C cathodes reached power densities of 1,963.1 and 2,178.6 mW/m2, respectively. Similarly, when utilizing graphitized mango seeds at 1,100°C, power densities of 2,171 and 2,151 mW/m2 were achieved for the new and standard cathodes, respectively. Furthermore, in continuous operation with a flow rate of 2 L/h, impressive chemical oxygen demand (COD) removal rates of 77% and 85% were achieved with corncob and mango seed anodes, respectively. This work highlights the significance of electrode design for enhancing MFC efficiency in electricity generation and wastewater treatment.

Electromagnetic field-enhanced novel tubular electrocoagulation cell for effective and low-cost color removal of beet sugar industry wastewater.

The treatment of real beet sugar mill effluent by a modified electrocoagulation process is proposed. An innovative design of an electromagnetic field-enhanced electrochemical cell consisting of a tubular screen roll anode and two cathodes (an inner and outer cathode) has been used. Different parameters have been investigated including current density, effluent concentration, NaCl concentration, rpm, number of screen layers per anode, and the effect of addition and direction of an electromagnetic field. The results showed that, under the optimum conditions, current density of 3.13 A/m2, two screens per anode, NaCl concentration of 12 g/l, and rotation speed of 120 rpm, the percentage of color removal was 85.5% and the electrical energy consumption was 3.595 kWh/m3. However, the presence of an electromagnetic field distinctly enhanced the energy consumption and the color removal percentage. Numerically, applying the magnetic field resulted in performing a color removal efficiency of 97.7% using a power consumption of 2.569 KWh/m3 which is considered a distinct achievement in industrial wastewater treatment process. The strong enhancement in color removal using a low power consumption significantly reduced the required treatment cost; the estimated treatment cost was 0.00017 $/h.m2. This design has proven to be a promising one for the continuous treatment of beet sugar industrial effluents and to be a competitor to the currently available techniques.

Carbon Nanofibers-Sheathed Graphite Rod Anode and Hydrophobic Cathode for Improved Performance Industrial Wastewater-Driven Microbial Fuel Cells.

Carbon nanofiber-decorated graphite rods are introduced as effective and low-cost anodes for industrial wastewater-driven microbial fuel cells. Carbon nanofiber deposition on the surface of the graphite rods could be performed by the electrospinning of polyacrylonitrile/N,N-Dimethylformamide solution using the rod as nanofiber collector, which was calcined under inert atmosphere. The experimental results indicated that at 10 min electrospinning time, the proposed graphite anode demonstrates very good performance compared to the commercial anodes. Typically, the generated power density from sugarcane industry wastewater-driven air cathode microbial fuel cells were 13 ± 0.3, 23 ± 0.7, 43 ± 1.3, and 185 ± 7.4 mW/m2 using carbon paper, carbon felt, carbon cloth, and graphite rod coated by 10-min electrospinning time carbon nanofibers anodes, respectively. The distinct performance of the proposed anode came from creating 3D carbon nanofiber layer filled with the biocatalyst. Moreover, to annihilate the internal cell resistance, a membrane-less cell was assembled by utilizing a poly(vinylidene fluoride) electrospun nanofiber layer-coated cathode. This novel strategy inspired a highly hydrophobic layer on the cathode surface, preventing water leakage to avoid utilizing the membrane. However, in both anode and cathode modifications, the electrospinning time should be optimized. The best results were obtained at 5 and 10 min for the cathode and anode, respectively.

Carbon Nanofiber Double Active Layer and Co-Incorporation as New Anode Modification Strategies for Power-Enhanced Microbial Fuel Cells.

Co-doped carbon nanofiber mats can be prepared by the addition of cobalt acetate to the polyacrylonitrile/DMF electrospun solution. Wastewater obtained from food industries was utilized as the anolyte as well as microorganisms as the source in single-chamber batch mode microbial fuel cells. The results indicated that the single Co-free carbon nanofiber mat was not a good anode in the used microbial fuel cells. However, the generated power can be distinctly enhanced by using double active layers of pristine carbon nanofiber mats or a single layer Co-doped carbon nanofiber mat as anodes. Typically, after 24 h batching time, the estimated generated power densities were 10, 92, and 121 mW/m2 for single, double active layers, and Co-doped carbon nanofiber anodes, respectively. For comparison, the performance of the cell was investigated using carbon cloth and carbon paper as anodes, the observed power densities were smaller than the introduced modified anodes at 58 and 62 mW/m2, respectively. Moreover, the COD removal and Columbic efficiency were calculated for the proposed anodes as well as the used commercial ones. The results further confirm the priority of using double active layer or metal-doped carbon nanofiber anodes over the commercial ones. Numerically, the calculated COD removals were 29.16 and 38.95% for carbon paper and carbon cloth while 40.53 and 45.79% COD removals were obtained with double active layer and Co-doped carbon nanofiber anodes, respectively. With a similar trend, the calculated Columbic efficiencies were 26, 42, 52, and 71% for the same sequence.

Under-oil superhydrophilic wetted PVDF electrospun modified membrane for continuous gravitational oil/water separation with outstanding flux.

Water in the world is becoming an increasingly scarce commodity and the membrane technology is a most effective strategy to address this issue. However, the fouling and low flux of the polymeric membrane remains the big challenges. Novel modified Polyvinylidene fluoride (PVDF) membrane was introduced, in this work, using a novel treatment technique for an electrospun polymeric PVDF membrane to be used in oil/water separation systems. The Characterizations of the modified and pristine membranes showed distinct changes in the phase and crystal structure of the membrane material as well as the wettability. The modification process altered the surface morphology and structure of the membrane by forming hydrophilic microspheres on the membrane surface. Therefore, the proposed treatment converts the membrane from highly hydrophobic to be a superhydrophilic under-oil when wetted with water. Accordingly, in the separation of oil/water mixtures, the modified membrane can achieve an outstanding flux of 20664 L/m2. hr under gravity, which is higher than the pristine membrane by infinite times. Moreover, in the separation of the emulsion, a high flux of 2727 L/m2. h was achieved. The results exhibited that the modified membrane can treat a huge amount of oily water with a minimal energy consumption. The corresponding separation efficiencies of both of oil/water mixtures and emulsion are more than 99%. The achieved characteristics for the modified and pristine membranes could be exploited to design a novel continuous system for oil/water separation with an excellent efficiency.

Amorphous SiO2 NP-Incorporated Poly(vinylidene fluoride) Electrospun Nanofiber Membrane for High Flux Forward Osmosis Desalination.

Novel amorphous silica nanoparticle-incorporated poly(vinylidine fluoride) electrospun nanofiber mats are introduced as effective membranes for forward osmosis desalination technology. The influence of the inorganic nanoparticle content on water flux and salt rejection was investigated by preparing electrospun membranes with 0, 0.5, 1, 2, and 5 wt % SiO2 nanoparticles. A laboratory-scale forward osmosis cell was utilized to validate the performance of the introduced membranes using fresh water as a feed and different brines as draw solution (0.5, 1, 1.5, and 2 M NaCl). The results indicated that the membrane embedding 0.5 wt % displays constant salt rejection of 99.7% and water flux of 83 L m(-2) h(-1) with 2 M NaCl draw solution. Moreover, this formulation displayed the lowest structural parameter (S = 29.7 µm), which represents approximately 69% reduction compared to the pristine membrane. Moreover, this study emphasizes the capability of the electrospinning process in synthesizing effective membranes as the observed water flux and average salt rejection of the pristine poly(vinylidine fluoride) membrane was 32 L m(-2) h(-1) (at 2 M NaCl draw solution) and 99%, respectively. On the other hand, increasing the inorganic nanoparticles to 5 wt % showed negative influence on the salt rejection as the observed salt flux was 1651 mol m(-2) h(-1). Besides the aforementioned distinct performance, studies of the mechanical properties, porosity, and wettability concluded that the introduced membranes are effective for forward osmosis desalination technology.