Cm2 Of Membrane Area Research Articles

Mitigating silica fouling in electro-electrodialysis: Anode compartment modification and process intensification approaches

Electro-electrodialysis (EED) based causticization of industrial (agro-based paper mills) green liquor experiences severe silicate fouling issues (especially in anode compartment) resulting frequent shutdown, dismantling, cleaning and reassembling challenges. Therefore, continuous causticization through EED process becomes difficult. Appropriate design modification of the anode compartment along with periodic silica removal could overcome frequent shutdown issues, and execution of EED process for longer duration. The novel mechanism of silicon removal using EED process by the precipitant is also presented. Their treatment performances in removing silicon were statistically evaluated and confirmed by instrumental techniques. Using modified design and 200 cm2 of membrane area, 500 mL of 2.56 mol·L−1 of NaOH (92% Na+ ion recovery) could be produced in 4 h by electrolyzing 500 mL of industrial green liquor under constant current density, 60 mA·cm−2. Proposed modification could result ∼21% improvement in caustic recovery/energy consumption compared to unmodified anode compartment. With improve the performance which is the average current efficiency 74.5% and energy consumption 4.42 kWh·kg−1, was recorded.

Return flow ion concentration polarization desalination: A new way to enhance electromembrane desalination

In electromembrane desalination processes such as electrodialysis (ED) and ion concentration polarization (ICP) desalination, ion-depleted boundary layers constitute the desalted, product stream, yet also cause high resistivity and voltage drop. Directly manipulating fluid flow streams is a new method to break this fundamental trade-off for electromembrane desalination. In this work, we are introducing a novel electromembrane desalination architecture that allows a feed stream to return to the feed inlet side of the membrane (hereby named as return-flow (RF) architecture) to improve the energy efficiency by re-distributing and controlling the depleted boundary layer, even at high current values. The technical feasibility of this idea was examined in ICP desalination process (RF-ICP) with a wide range of feed salinity from 10 to 70 g/L. For a partial desalination, RF-ICP (∼75 cm2 of membrane area) has achieved similar power consumption compared to batch-ED with 3 times bigger membrane area (200 cm2) with a higher area efficiency for salt removal, which translates into lower optimal desalination cost. The techno-economic analysis of RF-ICP have been performed for the treatment of 70 g/L brine waste. For partial desalination of 70 g/L brine down to 35 g/L, RF-ICP desalination achieved overall water cost as low as $2.57/m3 ($0.41/barrel). This could translate into reduction in total water cost up to 31% for zero brine release scenarios, depending on the concentrated brine treatment cost. These results show that return-flow architecture can improve the performance of electromembrane desalination, enabling more flexible water treatment for many real-world applications.

An ultra scale-down method to investigate monoclonal antibody processing during tangential flow filtration using ultrafiltration membranes.

The availability of material for experimental studies is a key constraint in the development of full‐scale bioprocesses. This is especially true for the later stages in a bioprocess sequence such as purification and formulation, where the product is at a relatively high concentration and traditional scale‐down models can require significant volumes. Using a combination of critical flow regime analysis, bioprocess modelling, and experimentation, ultra scale‐down (USD) methods can yield bioprocess information using only millilitre quantities before embarking on highly demanding full‐scale studies. In this study the performance of a pilot‐scale tangential flow filtration (TFF) system based on a membrane flat‐sheet cassette using pumped flow was predicted by devising an USD device comprising a stirred cell using a rotating disc. The USD device operates with just 2.1 cm2 of membrane area and, for example, just 1.7 mL of feed for diafiltration studies. The novel features of the design involve optimisation of the disc location and the membrane configuration to yield an approximately uniform shear rate. This is characterised using computational fluid dynamics for a defined layer above the membrane surface. A pilot‐scale TFF device operating at ~500‐fold larger feed volume and membrane area was characterised in terms of the shear rate derived from flow rate‐pressure drop relationships for the cassette. Good agreement was achieved between the USD and TFF devices for the flux and resistance values at equivalent average shear rates for a monoclonal antibody diafiltration stage.

Role of membrane pore polymerization conditions for pH responsive behavior, catalytic metal nanoparticle synthesis, and PCB degradation

This article describes the effects of changing monomer and cross-linker concentrations on the mass gain, water permeability, Pd-Fe nanoparticle (NP) loading, and the rate of degradation of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) of pore functionalized polyvinylidene fluoride (PVDF) membranes. In this study, monomer (acrylic acid (AA)) and cross-linker (N, N′- methylene-bis (acrylamide)) concentrations were varied from 10 to 20 wt% of polymer solution and 0.5–2 mol% of monomer concentration, respectively. Results showed that responsive behavior of membrane could be tuned in terms of water permeability over a range of 270–1 L m−2 h−1 bar−1, which is a function of water pH. The NP size on the membrane surface was found in the range of 16–23 nm. With increasing cross-linker density the percentage of smaller NPs (< 10 nm) increases due to smaller mesh size formation during in-situ polymerization of membrane. NP loading was found to vary from 0.21 to 0.94 mg per cm2 of membrane area depending on the variation of available carboxyl groups in membrane pore domain. The NPs functionalized membranes were then tested for use as a platform for the degradation of PCB 126. The observed batch reaction rate (Kobs) for PCB 126 degradation for per mg of catalyst loading was found 0.08–0.1 h−1. Degradation study in convective flow mode shows 98.6% PCB 126 is degraded at a residence time of 46.2 s. The corresponding surface area normalized reaction rate (Ksa) is found about two times higher than Ksa of batch degradation; suggesting elimination of the effect of diffusion resistance for degradation of PCB 126 in convective flow mode operation. These Pd-Fe-PAA-PVDF membranes and nanoparticles are characterized by TGA, contact angle measurement, surface zeta potential, XRD, SEM, XPS, FIB, TEM and other techniques reveal the details about the membrane surface, pores and nanoparticles size, shape and size-distribution. Statistical analysis based on experimental results allows us to depict responsive behavior of functionalized membrane. In our best knowledge this paper first time reports detail study on responsive behavior of pore functionalized membrane in terms of permeability, NPs size, metal loading and its effect on PCB 126 degradation in a quantified approach.

Multi‐fuel scaled‐down autothermal pure H2 generator: Design and proof of concept

This article presents experimental results of an autothermal scaled‐down system for H2 production. Pure atmospheric pressure H2, separated in situ by Pd–Ag membranes, is produced by steam reforming (SR) of methane, ethanol, or glycerol. Oxidizing the SR effluents in a separate compartment supplies the heat. The oxidation feed is axially distributed to avoid hotspots. The 1.3 L system, comprises 100 cm2 of membrane area, and generates H2 flow rate equivalent to 0.15 kW at an efficiency of ∼25%. This process leads to comparable performance when different fuels are used. A mathematical model, validated by the measurements, predicts that increasing the membrane area relative to the outer surface area will substantially increase the efficiency and power output. This design serves as proof of concept for on‐board pure H2 generators, with flexible fuel sources, and holds a great promise to reduce the need for special H2 transport and storage technologies for portable or stationary applications. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2112–2125, 2016

Boron removal by membrane contactors: the water that purifies water

The potential of membrane contactors for treating boron containing waters were investigated. In particular, experimental tests at lab scale on flat membrane modules with 40 cm2 of membrane area were carried out, to identify the effect of different parameters, such as temperature, flow rate, boron concentration, etc. on the efficiency of the process. Water was chosen as the extractant in order to avoid the pollution of the feed stream and two symmetric microporous hydrophilic flat membranes with different pore size and porosity were used. From these tests, it results that the boron removal increases with the extractant temperature and with the operating flow rates. However, it is independent on the initial boron concentration in the feed water. Moreover, higher removals are obtained with the membrane with larger pore size and higher porosity. Based on the experimental results, an integrated reverse osmosis-membrane contactor system, where the membrane contactor works on the reverse osmosis permeate, was proposed and designed for a 100 m3/h fresh water production (with a boron content ≤0.4 ppm). In particular, membranes with higher porosity and lower thickness than those used in the experimental tests were considered for the calculations, in order to work at 25°C (so, there is no need of heating the extractant stream) with reasonable membrane areas. The comparison of the proposed plant to that actually used, has shown that the proposed one appears to be more effective in terms of size, energy and chemical consumption, flexibility and modularity.