Paddle Wheel Research Articles

Environmentally friendly turbo jet aerator for sustainable multitrophic aquaculture

Aquaculture is an oxygen-dependent business; heterotroph biomass production is proportional to the oxygen supply to the aquaculture pond, therefore, intensive and supra-intensive aquaculture requires a large supply of oxygen. The use of paddle wheel aerators and the types of aerators available in the market today are generally wasteful in terms of energy use. This poster presents the test results of the Prototype Turbo Jet Aerator, which is named RA-TJA-SG1. This submersible aerator prototype was designed to be able to produce large amounts of oxygen with a small energy consumption (40 watts) using sustainable solar energy. Laboratory test results indicated that the RA-TJA-SG1 is able to increase the content of the concentration of dissolve oxygen in seawater at different salinity to the ideal concentration for intensive and supra intensive shrimp culture.

Electrochemical evolution of cobalt-carboxylate framework for efficient water oxidation

The overall water splitting is severely limited by the sluggish oxygen evolution reaction (OER), which further restricts the large-scale production of hydrogen for sustainable energy. These transition metal-based (oxy)hydroxides (TM(O)OH) are recognized as the most efficient non-noble electrocatalysts for OER, but the rational design and fabrication of TM(O)OH species remain a big challenge. Here we have synthesized a porous metal-organic framework (MOF, CoHKUST-1), and the rapid degradation of this MOF itself in alkaline solution is intrinsically stemmed from the metastable nature of the Co–O coordination bonds in the Co-based paddle wheel. By simply applying an electric potential, these synthesized Co-MOFs can be decomposed into the 2-dimensional nanosheet structure mainly consisting Co(OH)2 and CoOOH. The resulting CoOxHy nanosheets exhibit excellent OER performance to reach an overpotential of only 344 mV at 10 mA cm−2, and its Tafel slope is calculated to be 66.4 mV dec−1 indicating the fast reaction kinetics. The structural and morphological evolution under electrolysis is further proposed and evidenced by relevant physicochemical characterizations and theoretical calculations. The demonstrated work proves a feasible strategy for electrochemical design and fabrication of 2-dimensional TM(O)OH nanosheets for efficient water oxidation, which can be further applied in the future energy applications.

Prospect of development wind power plant taking into account the visual range of wind turbines location and determining the efficiency of the wind flow transition at rotors of veritical axis wind turbines.

Proposed method of calculating structural elements of blades of wind machines is not connected with intuitive selection of approximating functions of rigidity of structural elements. Application of the proposed design method showed necessity to introduce not only transverse reinforcing elements into the blade of the windwheel, but also longitudinal ones, which will allow to increase the generated electric energy from the small area of wind power plants location. The advantage of the proposed method for calculating the structural elements of wind machine blades is that it is not associated with an intuitive selection of approximating functions. The use of the calculation method showed the need to introduce not only transverse reinforcing elements, but also longitudinal ones into the wind wheel blade. We recommend that these elements be made in the form of a longitudinal corrugation laid between the transverse elements of the blade. The rigidity of these ribs will allow you to obtain a constant flow passing through the paddle wheel. The research conducted is not sufficient to determine the limits of the ratio of potential to electricity generation that can be achieved in practice at real wind farms. This value will depend on the stability of local air flows in the surface layer, spatial density, altitude, and the actual resistance of wind turbines. Further study of the interaction of these parameters is necessary, which is the focus of our current and future research.

Synthesis and crystal structure of catena-poly[[tetra-μ-acetato-copper(II)]-μ-6-eth-oxy-N 2,N 4-bis-[2-(pyridin-2-yl)eth-yl]-1,3,5-triazine-2,4-di-amine

The title compound, [Cu2(C19H23N7O)(C2H3O2)4] n , was obtained via reaction of copper(II) acetate with the coordinating ligand, 6-eth-oxy-N 2,N 4-bis-[2-(pyridin-2-yl)eth-yl]-1,3,5-triazine-2,4-di-amine. The crystallized product adopts the monoclinic P21/c space group. The metal core exhibits a paddle-wheel structure typical for dicopper tetra-acetate units, with triazine and pyridyl nitro-gen atoms from different ligands coordinating to the two axial positions of the paddle wheel in an asymmetric manner. This forms a coordination polymer with the segments of the polymer created by the c-glide of the P21/c setting of the space group. The resulting chains running along the c-axis direction are held together by intra-molecular N-H⋯O hydrogen bonding. These chains are further packed by dispersion forces, producing an extended three-dimensional structure.

Simultaneous quantitative recognition of all purines including N6-methyladenine via the host-guest interactions on a Mn-MOF

Simultaneous quantitative recognition of all purines including N6-methyladenine via the host-guest interactions on a Mn-MOF

Ring opening polymerization of d,l-lactide and ε-caprolactone catalysed by (pyrazol-1-yl)copper(ii) carboxylate complexes.

1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L) reacts with [Cu(OAc)2] and C6H5COOH, 4-OH-C6H4COOH, 2-Cl-C6H4COOH and (3,5-NO2)2-C6H3COOH to afford the copper complexes [Cu2(C6H5COO)4(L)2] (1), [Cu2(4-OH-C6H4COO)4(L)2] (2), [Cu2(2-Cl-C6H4COO)4(L)2]n (3) and [Cu{(3,5-NO2)2-C6H3COO}2L]n (4) which are characterised by IR, mass spectrometry, elemental analyses, and X-ray crystallography. The structural data revealed two geometries that are adopted by the complexes: (i) paddle wheel in 1, 2·7H2O, 3 and (ii) regular chains in 3 and 4. Magnetic studies show strong antiferromagnetic couplings in the paddle wheel complexes and a weak antiferromagnetic coupling in the monometallic chain one. Catalysis studies performed with these complexes (1–4) showed that they initiate ring opening polymerization (ROP) of ε-caprolactone (ε-CL) under solvent-free conditions and d,l-lactide in toluene at elevated temperatures. Polycaprolactone (PCL) and poly(d,l-lactide) (PLA) obtained from the polymerization reactions are of low molecular weights (858 for PCL and 602 Da for PLA for initiator 1) and polydispersity indices (typically 2.16 for PCL and 1.64 for PLA with 1 as the initiator). End group analysis of the polymers, determined by MALDI-ToF MS, indicates that the polymers have benzoate, hydroxyl, methoxy and cyclic end groups.

Computerized Optimization of Microalgal Photosynthesis and Growth

ABSTRACT We describe the use of a novel, computerized, multiple outdoor microalgal growth system to achieve conditions maximizing high photosynthesis and biomass production rates. We applied this system to determine the effects of multiple environmental and culture parameters such as light, temperature, pH, and mode of mixing and CO2 supply, and their combinations on the rates of algal photosynthesis, respiration, and growth. We continuously monitored the following parameters: pH, temperature, dissolved oxygen, and light, concomitantly with algal growth and biomass production rates. In particular, we likewise monitored and determined the dramatic effects of CO2 supply, mixing by paddle wheel or bubbling air modes, on algal biomass production. The isolated and synergistic effects of each factor and operation regime were measured and are discussed. We found that the diel range of maxima to minimal pH and oxygen levels strongly correlated with container performance, and were controllable by CO2 supply and mixing regime. We conclude that mixing by bubble aeration was the most important growth-rate controlling factor. It limited the build-up of high oxygen and pH levels that reduce photosynthesis that were measured by O2 evolution. In this study, OD measurements calibrated with biomass concentrations were used to calculate growth rates and estimate the photosynthetic rates of the microalgae. The potential of algae as a source of food, feed, biofuel, and fine chemicals has been widely recognized, but their competitiveness depends on areal yields. Our results allow us to recommend culture parameters that increase areal biomass yields, regardless of the algal species, thereby bringing microalgal mass culture closer to economic viability.

Mixing strategies combined with shape design to enhance productivity of a raceway pond

This paper focuses on mixing strategies and designing shape of the bottom topographies to enhance the growth of the microalgae in raceway ponds. A physical-biological coupled model is used to describe the growth of the algae. A simple model of a mixing device such as a paddle wheel is also considered. The complete process model was then included in an optimization problem associated with the maximization of the biomass production. The results show that non-trivial topographies can be coupled with some specific mixing strategies to improve the microalgal productivity.

Assessment of standard aeration efficiency of different aerators and its relation to the overall economics in shrimp culture

Aerators are essential for maintaining the dissolved oxygen level in shrimp culture operations. Many types of aerators are promoted as suitable for shrimp culture, but their comparative efficiencies and water circulation patterns are least understood. The aerators viz, modified paddlewheel, Scorpion jet, Venture jet, Wavesurge were evaluated to compare the standard aeration efficiency at different saline conditions with the commonly used paddle wheel. The modified paddlewheel had the highest mean aeration efficiency of 2.018 kg O2/ kWh at 35‰, followed by the paddlewheel with 1.434 kg O2/ kWh at 20‰ water salinity. Compared to this, the Scorpion jet and the Wavesurge have shown the highest aeration efficiency of 0.667 and 0.412 kg O2/ kWh at 20 and 35‰ water salinities, respectively, whereas the Venture jet has given only. The aerator's performance was better at medium water salinities (20 and 35‰) than low (5‰) or high saline (50‰) conditions. In addition to aeration, the paddlewheel aerator has given the maximum water circulation speed 3 ft/sec and coverage distance of 24 m. The cost economics were derived by keeping all other expenses constant except aeration associated costs. The internal rate of returns in shrimp culture with a modified paddle wheel was 127 % compared to the commonly used paddle wheel (120 %). However, the scorpion and wavesurge aerators have shown returns of 47 % and 27 % respectively across the salinities. The selection and sizing of aerators based on the biomass and efficiency of the aeration systems can make considerable headway in decreasing the cost of production and energy use.

Aquatech: A Smart Fish Farming Automation and Monitoring App

This study is sought to address the problem of the ‘manual’ monitoring system which renders “low” accuracy on monitoring the water value. The existing practice of manual testing uses a refractometer to check the salinity level device and pond thermometers for testing the water temperature of fish farm water environment. It needs extra effort and more workers to regularly monitor such as: opening and closing the gate valve to control the level of fresh and saltwater needed to become accurate ‘brackish’ water. On the contrary, this research wants to establish an IOT-Based project to attempt solving this existing problem. Hence, this may create a unique system to help monitor and maintain the salinity, temperature and water level using the sensors that triggers the relay switches to automatically open or close the gate valves and operate the motors depending on the parameter’s desirable range values that the sensors passed. The sensors and motors also monitor the pond environment between air and water for sufficient increase of oxygen concentration in farm water environment. Likewise, this new IOT-based monitoring system specifically uses Raspberry PI 3B+, Wemos Wireless Microcontroller, Sensors (for water level, conductivity, temperature, toxic gases) and Relay Switches, Equipment (i.e. paddle wheel aerator, water pump and pipe valve), Computer and Mobile Phone, Long Range access point/Point to Point network to cover the entire fish farming areas for wide ranges wireless connectivity, and USB modem which sends SMS messages to keep the management updated with the current water behavior in the farm.

ALBA: A comprehensive growth model to optimize algae-bacteria wastewater treatment in raceway ponds

This paper proposes a new model describing the algae-bacteria ecosystem evolution in an outdoor raceway for wastewater treatment. The ALBA model is based on mass balances of COD, C, N and P, but also H and O. It describes growth and interactions among algae, heterotrophic and nitrifying bacteria, while local climate drives light and temperature. Relevant chemical/physical processes are also included. The minimum-law was used as ground principle to describe the multi-limitation kinetics. The model was set-up and calibrated with an original data set recorded on a 56 m2 raceway located in the South of France, continuously treating synthetic wastewater. The main process variables were daily measured along 443 days of operations and dissolved O2 and pH were on-line recorded. A sub-dataset was used for calibration and the model was successfully validated, along the different seasons over a period of 414 days. The model proved to be effective in reproducing both the short term nycthemeral dynamics and the long-term seasonal ones. The analysis of different scenarios reveals the fate of nitrogen and the key role played by oxygen and CO2 in the interactions between the different players of the ecosystem. On average, the process turns out to be CO2 neutral, as compared to a standard activated sludge where approximately half of the influent carbon will end up in the atmosphere. The ALBA model revealed that a suboptimal regulation of the paddle wheel can bring to several detrimental impacts. At high velocity, the strong aeration will reduce the available oxygen provided by photo-oxygenation, while very low aeration can rapidly lead to oxygen inhibition of the photosynthetic process. On the other hand, during night, the paddle wheel is fundamental to ensure enough oxygen in the system to support algal-bacteria respiration. The model can be used to support advanced control strategies, including smart regulation of the paddle wheel velocity to more efficiently balance the mixing, aeration and degassing effects.

Computational fluid dynamics (CFD) modeling of removal of contaminants of emerging concern in solar photo-Fenton raceway pond reactors

The impact of mixing and hydrodynamics on the removal of contaminants of emerging concern (CECs) detected in a secondary WWTP effluent by the solar photo-Fenton process in a pilot scale Raceway Pond Reactor (RPR) was investigated by computational fluid dynamics (CFD). The CFD model incorporated the solar photo-Fenton CECs oxidation kinetics at neutral pH with Fe3+-EDDS, the radiation transport through the water, and the turbulent flow field produced by a paddle wheel mixer. The fluid dynamics was solved by a transient-multiphase flow model (Volume of Fluid with Sliding Mesh Model) and by a steady-state momentum source domain (SD) model. Experimental RPR mixing time and CECs removal under transient conditions validated the models. The computationally faster SD model predicted the CECs removal varying the paddle wheel rotational speed, the solar irradiance, and fluid residence time. Deviations from an ideal CSTR were significative (>10%) when the CECs half-life/mixing time ratios were <1, while residence time had minor influence. The mixing effects were amplified in a scaled-up RPR and treatment capacity decreased 10% compared with a CSTR. Overall, this study reveals that the design of hydrodynamics in large-scale RPRs must be carefully examined to reduce power consumption while increasing mixing performance.

Doubly Interpenetrated Metal-Organic Framework of pcu Topology for Selective Separation of Propylene from Propane.

Adsorptive separation is an appealing alternative technology to reduce the high energy and capital cost of the distillation separation of propylene/propane; however, it is very challenging to realize. A new flexible metal-organic framework (MOF) material [Zn2(BDC-Cl)2(Py2TTz)] with a doubly interpenetrated pillared paddle wheel structure of pcu (primitive cubic) topology has been realized for this difficult separation for the first time. Through a judicious choice of linkers, the framework has small pore apertures that lead to much more propylene adsorption than propane. The selective adsorption relies on the sieving effect of the flexible framework. The column breakthrough experiment further demonstrated that efficient separation can be achieved under dynamic conditions.

A Selenophene-Incorporated Metal-Organic Framework for Enhanced CO2 Uptake and Adsorption Selectivity.

A new metal–organic coordination polymer [Zn2(sedc)2(dabco)] (1se; sedc2− = selepophene-2,5-dicarboxylate; dabco = 1,4-diazabicyclo[2.2.2]octane) was synthesized and characterized by single-crystal X-ray diffraction analysis. This MOF is based on {Zn2(OOCR)4N2} paddle wheels and is isoreticular to the family of [Zn2(bdc)2(dabco)] derivatives (1b; bdc2− = 1,4-benzenedicarboxylate) with pcu topology. The gas adsorption measurements revealed that 1se shows a 15% higher CO2 volumetric uptake at 273 K and 28% higher CO2 uptake at 298 K (both at 1 bar) compared to the prototypic framework 1b. Methane and nitrogen adsorption at 273 K was also investigated, and IAST calculations demonstrated a pronounced increase in CO2/CH4 and CO2/N2 selectivity for 1se, compared with 1b. For example, the selectivity factor for the equimolar CO2/CH4 gas mixture at 1 bar = 15.1 for 1se and 11.9 for 1b. The obtained results show a remarkable effect of the presence of selenium atom on the carbon dioxide affinity in the isoreticular metal–organic frameworks with very similar geometry and porosity.

Synthesis of tricarboxylic acid based metal organic frameworks: Structural and gas adsorption studies

Two folded interpenetrating metal organic frameworks (MOFs) viz. {[Zn4(L)2(NO3)(H2O)3]+ [S1]}n(LZn) and {[Cd4(L)2(NO3)(DMF)8(H2O)](NO3)(DMF)2(S2)}n (LCd) where S1 denotes squeezed nitrate anions and solvent molecules and S2 denotes the squeezed solvent molecule, have been synthesized from (4,4′,4′'-(((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(azanediyl))tribenzoic acid) (H3L) ligand and Zn(NO3)2•6H2O/Cd(NO3)2•4H2O metal salts by solvothermal process. The structural analysis showed that both LZn and LCd are two dimensional (2D) interpenetrating metal organic frameworkscontaining binuclear paddle wheel secondary building units (SBUs), Zn2(COO)3 and Cd2(COO)3, with hexagonal (hcb) net topology having 3-connected uninodal net. In LZn, both interpenetrating frameworks are vertical while in LCd, these are parallel to each other. Thermogravimetric analysis showed that both MOFs are stable up to 350 °C. Gas adsorption study demonstrated that these MOFs are selective towards CO2 over N2 gas due to sieving effect as well as Lewis acid-Lewis base interaction.

Introducing Joule’s Paddle Wheel Experiment in the Teaching of Energy: Why and How?

History of science provides access to a reservoir of meaningful experiments that can be studied and reproduced in classrooms. This is the case of Joule’s paddle-wheel experiment which displays the potentiality to help students improve their understanding of the concept of energy. This experiment has been mentioned in many physics textbooks during the twentieth century. Recently, it has received renewed attention by several researchers in science education. However, the accounts of Joule’s experiment proposed by these researchers are at variance with each other: either in terms of equivalences, in terms of energy change, or in terms of energy transformation and Rankine’s definition. This raises several questions: What is their respective contribution to the understanding of the historical emergence of the energy concept, and to the understanding of the very meaning of this concept? Are these accounts concurrent? Eventually, how can they help for the teaching energy? To investigate these questions, historical details concerning this experiment are first considered. It is stressed that Joule did not made use of the concept of energy, and instead described his experiment in terms of conversion of living force into heat. The three accounts of Joule’s experiment are then presented and their respective contribution discussed. By emphasizing different aspects of this experiment, they are shown to suggest different strategies for teaching energy. For all that, they are not contradictory and, considered together, they bring to light the great potential of Joule’s experiment to foster students understanding of this concept.

In-line monitoring of low drug concentration of flowing powders in a new sampler device.

A novel sampler device for flowing powders was tested to quantify drug concentrations as low as 0.76% w/w in pharmaceutical powder blends. The sampler device was developed based on the powder flow behavior within a tablet press feed frame, following the principles laid down in the Theory of Sampling. Two Near-Infrared (NIR) spectroscopic calibration models were developed with powder blends that varied from 0.52 to 2.52% w/w and 1.51-4.52% w/w. The calibration models were able to determine caffeine concentration in test set blends with root mean square error of predictions and bias below 0.1% w/w. Samples were collected from the sampler device and analyzed by ultraviolet-visible (UV-Vis) to determine the caffeine concentration. A high agreement between the in-line NIR predictions and the sampled UV-Vis results was found. The paddle wheel speed in the sampler can be varied up to ±10% without affecting NIR predictions; however, the models did not respond adequately to a 25% increase in this speed. Variographic analysis showed that the sampler device may quantify low drug concentrations with nugget effects below 0.0050 (%w/w)2. This study demonstrate that the sampler device may handle throughputs up to 45kg/h, without significantly affecting the physical properties of powder blends.

Synthesis, characterizations, crystal structures, and theoretical studies of copper(II) and nickel(II) coordination complexes

In the present study, we report synthesis, characterization, structural and theoretical studies of two copper(II) complexes, [Cu(py)2(L1)2] (1) and [Cu(phen)(Ac)2-Cu2(Ac)4]n (2), and a nickel(II) complex, [Ni(bipy)(L)(Ac)] (3), where py = pyridine, L1 = 3,5-dichloro-2-hydroxybenzaldehyde, phen = 1,10-phenanthroline, Ac = acetate ion, bipy = 2,2’-bipyridine and HL = 4-bromo-2-(Z)-(naphthalene-2-ylimino)methyl) phenol. The new complexes were fully characterized using microanalysis, FAB-mas (m/z), FT-IR, UV-Vis and fluorescence spectra, X-band EPR spectroscopy and then by single crystal X-ray diffraction studies. X-ray studies of 1 and 3 revealed distorted octahedral geometries. Complex 2 is a coordination polymer built by an octahedral copper unit Cu(phen)(Ac)2 alternating with paddle wheel species Cu2(Ac)4, located on a crystallographic center of symmetry, where an acetate anion bridges the two crystallographic independent copper ions. The fluorescence intensities and quantum yields of 1 and 2 were found to be more compared to 3. The preliminary tests in the potential application for theoretical biological activities of compounds have also been studied. Furthermore, we also performed quantum chemical calculations to get insights into the structure-property relationships of the synthesized complexes. The quantum chemical calculations were used for theoretical calculations of linear polarizability and third-order nonlinear optical polarizability (γ) for 1, 2 and 3. Besides this, the theoretical calculations, including the analysis of frontier molecular orbitals and electrostatic potential diagrams, are used to highlight the theoretical aspects of metal to ligand charge transfer (MLCT) processes in the studied complexes.

Conservation of Energy: Missing Features in Its Nature and Justification and Why They Matter

Misconceptions about energy conservation abound due to the gap between physics and secondary school chemistry. This paper surveys this difference and its relevance to the 1690s–2010s Leibnizian argument that mind-body interaction is impossible due to conservation laws. Justifications for energy conservation are partly empirical, such as Joule’s paddle wheel experiment, and partly theoretical, such as Lagrange’s statement in 1811 that energy is conserved if the potential energy does not depend on time. In 1918 Noether generalized results like Lagrange’s and proved a converse: symmetries imply conservation laws and vice versa. Conservation holds if and only if nature is uniform. The rise of field physics during the 1860s–1920s implied that energy is located in particular places and conservation is primordially local: energy cannot disappear in Cambridge and reappear in Lincoln instantaneously or later; neither can it simply disappear in Cambridge or simply appear in Lincoln. A global conservation law can be inferred in some circumstances. Einstein’s General Relativity, which stimulated Noether’s work, is another source of difficulty for conservation laws. As is too rarely realized, the theory admits conserved quantities due to symmetries of the Lagrangian, like other theories. Indeed General Relativity has more symmetries and hence (at least formally) more conserved energies. An argument akin to Leibniz’s finally gets some force. While the mathematics is too advanced for secondary school, the ideas that conservation is tied to uniformities of nature and that energy is in particular places, are accessible. Improved science teaching would serve the truth and enhance the social credibility of science.

Non-thermal plasma-assisted catalytic CO2 conversion over Zn-TCPP 2D catalyst

There is still a growing interest in CO2 conversion into useful compounds. Plasma technology is a highly promising alternative due to its non-equilibrium nature, crucial for CO2 dissociation processes. In this study we present, the non-thermal plasma-assisted catalytic CO2 reduction to CO on 2D Zn-containing paddle wheel structures based on TCPP. The catalytic efficiency of this MOF material is shown to be high. The experimental data from HRTEM, adsorption and FTIR analyses lead to the simplified model mechanism of this process.