Aquaporin-Based Biomimetic Membranes for Low Energy Water Desalination and Separation Applications

The emergence of biomimetic materials developed using nature's inspiration and biological domains can drive a paradigm shift in the design and operation of future-generation materials in separation applications. In recent years, biomimetic membranes have drawn interest of many researchers for water treatment applications. Among the biomimetic membranes, protein-based membranes, specifically those synthesized by aquaporin, have received much attention in recent years due to their high osmotic water permeability and excellent ability to remove small molecules, thereby overcoming the trade-off between the water flux and the contaminant's rejection. The separation efficiency and fouling properties are significantly improved by taking advantage of the strategies evolved in nature. This review provides a comprehensive overview of the state-of-the-art aquaporin-based biomimetic membranes (ABMs), mainly focusing on their synthesis, characterization, and performance as selective layer in composite membranes for reverse osmosis, nanofiltration, and forward osmosis for water desalination. Fabrication methods and characterization techniques of ABMs and their performance in water desalination are also reviewed, while the main obstacles for their successful commercial viability in wastewater treatment are provided. The applications of ABMs in various separation processes other than water desalination and their potential market are presented to inspire future researchers in this versatile area.     

Pore-scale study based on lattice Boltzmann method of density driven natural convection during CO2 injection project

Saline aquifers are chosen for geological storage of greenhouse gas CO₂ because of their storage potential. In almost all cases of practical interest, CO₂ is present on top of the liquid and CO₂ dissolution leads to a small increase in the density of the aqueous phase. This situation results in the creation of negative buoyancy force for downward density-driven natural convection and consequently enhances CO₂ sequestration. In order to study CO₂ injection at pore-level, an isothermal Lattice Boltzmann Model (LBM)with two distribution functions is adopted to simulate density-driven natural convection in porous media with irregular geometry obtained by image treatment. The present analysis showed that after the onset of natural convection instability, the brine with a high CO₂ concentration infringed into the underlying unaffected brine, in favor of the migration of CO₂ into the pore structure. With low Rayleigh numbers, the instantaneous mass flux and total dissolved CO₂ mass are very close to that derived from penetration theory (diffusion only), but the fluxes are significantly enhanced with high Ra number. The simulated results show that as the time increases, some chaotic and recirculation zones in the flow appear obviously, which promotes the renewal of interfacial liquid, and hence enhances dissolution of CO₂ into brine. This study is focused on the scale of a few pores, but shows implications in enhanced oil/gas recovery with CO₂ sequestration in aquifers.     

Removal of Rhodamine B from aqueous solutions and wastewater by walnut shells: kinetics,equilibrium and thermodynamics studies

An adsorption study of Rhodamine B (RB) dye from aqueous solutions was carried out using walnut shells pretreated by different methods. In addition to the effects of the pretreatment, the effects of various parameters like pH, adsorbent dose, contact time, initial dye concentration and temperature on the adsorption of RB was studied. The adsorption process was highly pH dependent and a maximum adsorption was achieved at pH 3.0. The best fit for the rates of dye adsorption was a pseudo-second-order kinetic model with good correlation coefficients (R²>0.99). Langmuir isotherms were used to determine that the maximum loading capacity of the different walnut shells and the RB capacities ranged from 1.451–2.292 mg·g^-1. The dye adsorption was also evaluated thermodynamically. Positive standard enthalpy (?H°) values were obtained indicating that the RB adsorption process is endothermic as well as ?G° and ?S° values showed that adsorption process is spontaneous with an increased randomness at the solid-liquid interface. Desorption studies were carried out to explore the feasibility of regenerating the used walnut shells and it was found that 97.71%–99.17% of the retained RB was recovered with 0.1 mol?L^-1 NaOH solution. The walnut shells were also successfully used to remove RB from industrial effluents.     

Adsorption of rhodium by modified mesoporous cellulose/silica sorbents: equilibrium,kinetic, and thermodynamic studies

A cellulose/silica hybrid was fabricated through the simultaneous deposition of silica and cellulose from their blends. The product was treated with ethylenediamine then carbon disulfide to functionalize amine and thio moieties to the hybrid surface to obtain R-N and R-NS, respectively. The new sorbents obtained were characterized by FT-IR, SEM, and BET. The data obtained indicated the functionalization of amine and thio moieties to the hybrid surface and the formation of thermally stable mesoporous particles with surface area of 319 and 63.5 m² for R-N and R-NS, respectively. Batch and column studies were carried out to verify the behavior of the two sorbents towards Rh(III) ions from their chloride solutions. The batch studies showed maximum uptake capacity values of 51 and 60 mg g^?1, where column studies showed 76.5 and 90 mg g^?1 for R-N, R-NS, respectively. The data obtained were interpreted to get the equilibrium, isotherm, kinetics, and thermodynamics adsorption parameters. The adsorption process is favorable and dominated by entropic changes, follow the pseudo-second order kinetics, and fitted well with Langmuir and Dubinin–Radushkevitch adsorption isotherms. The data obtained from batch and column studies indicates the applicability of the obtained cellulose/silica composites in retrieval of Rh(III) ions at higher efficiency.     

An information-theoretic framework for field monitoring using autonomously mobile sensors

We consider a mobile sensor network monitoring a spatio-temporal field. Given limited caches at the sensor nodes, the goal is to develop a distributed cache management algorithm to efficiently answer queries with a known probability distribution over the spatial dimension. First, we propose a novel distributed information theoretic approach assuming knowledge of the distribution of the monitored phenomenon. Under this scheme, nodes minimize an entropic utility function that captures the average amount of uncertainty in queries given the probability distribution of query locations. Second, we propose a correlation-based technique, which only requires knowledge of the second-order statistics, relaxing the stringent constraint of a priori knowledge of the query distribution, while significantly reducing the computational overhead. We show that the proposed approaches considerably improve the average field estimation error. Further, we show that the correlation-based technique is robust to model mismatch in case of imperfect knowledge of the underlying generative correlation structure.     

Physico-Chemical Aspects on Uranium and Molybdenum Extraction from Aqueous Solution by Synthesized Phosphinimine Derivative Chelating Agent

Journal of Inorganic and Organometallic Polymers and Materials - To retain uranium and molybdenum ions from G.Gattar leach liquor (GI), North Eastern Desert, Egypt, a new fabricated chelating...     

Growth,Yield and Physiological Characteristics of Maize (Zea mays L.) at Two Different Soil Moisture Regimes by Supplying Silicon and Chitosan

Silicon - Water deficit is an important factor to challenge food security, particularly in arid and semi-arid climates. In present experiment, silicon (Si) and chitosan were evaluated to affect the...     

IAMonSense: multi-level handwriting classification using spatiotemporal information

International Journal on Document Analysis and Recognition (IJDAR) - Online handwriting classification has become an open research problem as it serves as a preliminary step for handwriting...