Sodium Thiosulfate Pentahydrate Research Articles

Vachelia nilotica seed-mediated green synthesis of sulfur nanoparticles (SNPs) and evaluation of anticancer & antifungal activities

Sulfur nanoparticles (SNPs) have been successfully synthesized by applying Vachelia nilotica seed extract as a bioactive aqueous material by a disproportionation reaction of sodium thiosulfate pentahydrate (Na2S2O3 .5H2O) with a 10% hydrochloric acid (HCl) at room temperature. The synthesized SNPs were characterized by UV–Visible, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction (XRD) techniques. The usual size of SNPs was determined by an XRD study and calculated with the Debye–Scherrer formula. The SNPs are crystalline with a calculated average size of 45 nm. The SEM and TEM analyses revealed spherical shape and size around 55 nm of SNPs. The synthesized SNPs were screened for their antifungal activity against M. furfur species and for anticancer activities against (MCF-7, HepG2) cell lines. The obtained results suggested towards moderate to good antifungal and excellent anticancer activities.

Plant extract-mediated biosynthesis of sulphur nanoparticles and their antibacterial and plant growth-promoting activity

This study reports green synthesis of sulphur nanoparticles using sodium thiosulfate pentahydrate (Na2S2O35H2O) and Cannabis sativa leaf extracts. X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM) was employed to examine the crystallinity of the particles and morphological characteristics, proved both spherical and rod-shaped morphology of the S NPs having porous nature. The FTIR spectra revealed the interaction of the synthesized SNPs with the biomolecules present in the leaf extract. UV–VIS spectral investigations confirmed the production of SNPs from C. sativa leaf extract and that these SNPs can be used for visible region photocatalysis for the removal of pollutants from wastewater. Energy dispersive X-ray (EDX) spectrum of the SNP shows a single peak around 2.4 keV, confirmed S NPs purity. TEM image revealed the formation of mainly nanorods having a width of ∼20–25 nm and a length of 50–100 nm. Furthermore, some spherical particles (∼20–30 nm) were also formed. HRTEM image of the rod-shaped particles clearly shows the crystal fringe spacing of 0.38 nm. Further, disc diffusion method (DDM) was used to check the antibacterial activity of S NPs against gram-positive S. aureus (MTCC737) 18 ± 0.12 mm and gram-negative bacteria against E. coli (MTCC443) 21.5 ± 0.12 mm, A. salmonicida (MTCC1522) 19.1 ± 0.12 mm, K. pneumoniae (MTCC3384) 17.8 ± 0.10 mm. Among all the strains of bacteria, E. coli (MTCC443) showed a maximum zone of inhibition of 21.5 ± 0.12 mm and its antibacterial activity is somewhat like streptomycin sulfate. These SNPs also promote growth of C. sativa in pot experiment, resulting in a 30 % increase in biomass, 90 cm in shoot length and 28 cm in root length and higher fresh and dry weight (50g and 20g, respectively) with 1.0 mg mL−1 NPs treatment. In addition, SEM-EDX confirmed the accumulation of nanomaterial in plant leaves. This environmentally friendly approach to SNP synthesis using C. sativa extracts demonstrates both potent antibacterial properties and plant growth-promoting effects, making it a promising solution for agriculture and biomedicine.

Experimental investigation on heating performance of long- and short-term PCM storage in Chinese solar greenhouse

Phase change material (PCM) board on north wall of the greenhouses can absorb and store solar heat during the daytime, then releases it at night to provide the thermal environment for crop growth. However, its capability to regulate the greenhouse temperatures in severe winter is limited, necessitating an additional heat source. The heat gap within the greenhouse can be replenished flexibly and promptly by controllable triggering of supercooled salt hydrate for long-term heat storage. This study proposed a synergetic energy storage and release system, combining the short-term storage and passive release of the PCM wallboard with the long-term storage and active triggering solidification of the supercooled salt hydrate in separate storage unit. The temperature regulation effect of this synergetic system was experimentally investigated in a test Chinese greenhouse. The results showed that the combination of the PCM north wallboard with the supercooled salt hydrate storage unit reduced the daytime average temperature by 2.0 °C ~ 3.8 °C compared with the control greenhouse. In sunny days, the PCM north wallboard could meet the nighttime heat demand of the greenhouse with the average temperature rise of 5.2 °C ~ 6.7 °C. In severe weather, by triggering supercooled sodium acetate trihydrate (SAT, CH3COONa·3H2O, Tm = 58.0 °C) at late night, the temperature rose by 5.3 °C in 1 h, effectively heating for 5 h. While supercooled sodium thiosulfate pentahydrate (STP, Na2S2O3·5H2O, Tm = 48.5 °C) was triggered, the temperature rose by 3.3 °C in 1 h, effectively heating for 4 h. Furthermore, the synergetic system was still effective for greenhouses under ventilation and irrigation conditions during the day. This study provides guidance for the development of synergetic PCM systems with long- and short-term solar thermal storage and release for greenhouse heating.

Effect of Sintering Time and Cl Doping Concentrations on Structural, Optical, and Luminescence Properties of ZnO Nanoparticles

Zinc oxide (ZnO) nanoparticles were synthesized hydrothermally using zinc acetate dihydrate and sodium thiosulfate pentahydrate precursors. The synthesized powders were sintered in air at 600 °C for different durations with a Cl-doping concentration of 25 mg/g. The optimal sintering time was found to be 5 h, resulting in the successful formation of the ZnO phase with small particle sizes of around 90 nm, nominal atomic fractions of Zn and O (~50%, ~50%), and increased luminescence intensity. The ideal concentration of Cl was discovered to be 25 mg/g of ZnO, which resulted in the highest luminescence intensity. The ZnO luminescence characteristics were observed in emission bands peaking at approximately 503 nm attributed to the transition from oxygen vacancies. A considerable improvement in the emission intensity was observed with increased Cl doping concentration, up to eight orders of magnitude, compared to pristine ZnO nanoparticles. However, the luminescence intensity decreased in samples with higher concentrations of Cl doping due to concentration quenching. These preliminary outcomes suggest that Cl-doped ZnO nanoparticles could be used for radiation detector development for radon monitoring and other related applications.

Numerical investigation on thermal performance of a solar greenhouse with synergetic energy release of short- and long-term PCM storage

To address the problem of low greenhouse temperature at late night in north China, a new strategy of synergetic release of short- and long-term PCM heat storage is proposed in this paper, i.e. supercooled salt hydrate units are activated to release seasonally stored latent heat after the organic PCM north wallboard with daily storage cannot provide the required indoor temperature. To achieve this strategy, a microclimate model considering multiple greenhouse elements, including solar radiation, crops, indoor air, water vapor, soil and PCMs, is developed and 3D computational fluid dynamic (CFD) simulations are employed to examine the thermal performances of this strategy under Beijing climate conditions. The results demonstrated that the new strategy promotes the greenhouse temperature suitable for tomato growth (15 °C) throughout the whole night in winter. The organic PCM (Tm = 25 °C) wallboard can reduce the daytime indoor temperature by 0.5–1.5 °C and increase the nighttime indoor temperature by 4–5.5 °C than without PCM wallboard on January 1st. But the greenhouse temperature with this single daily storage is still lower than the required 15 °C after 4:00 a.m. With consideration of the unit numbers and heating effects, triggering two supercooled sodium thiosulfate pentahydrate (STP) units at one time (rather than sodium acetate trihydrate (SAT) and calcium chloride hexahydrate (CCH)) is the reasonable choice for greenhouse heating under present conditions. The system can achieve synergetic energy release across seasons, days and nights, regulate the thermal environment in the greenhouse, and promote the quantity and quality of crop output.

Synthesis of Aryl Amides from Acyl-Bunte Salts and Aryl Azides.

In this study, we developed an efficient method for the synthesis of aryl amides from sodium thiosulfate pentahydrate, organic anhydrides, and aryl azides. Sodium thiosulfate may be used as the sulfur source, which reacts with anhydrides to generate acyl-Bunte salt; this salt reacts with aryl azides via the in situ generation of thiocarboxylate. Using our method, we successfully synthesized a key bioactive compound. The advantages of one-pot two-step reactions include operational simplicity, structurally diverse products with favorable yields, use of less toxic odorless reagents, and easy applicability to large-scale operations.

Optimization of low-temperature preheating strategy for Li-ion batteries with supercooling phase change materials using response surface method

The supercooling phase change materials (SPCMs) for preheating lithium-ion batteries (LIBs) in cold environments have demonstrated efficacy and improved the discharge performance in practical applications. However, the bulky and heavy SPCM blocks and the uneven temperature distribution deteriorate the discharge performance of LIBs. In this paper, an optimization study based on the response surface method (RSM) is carried out on the low-temperature preheating strategy of LIBs using SPCMs to obtain a lightweight design with satisfactory performance. The three key factors of PCM thickness, gap, and PCM type are optimized based on six responses. The optimization goals are to minimize the preheating time, the maximum and average battery pack temperature, and the temperature difference between cells, as well as to maximize the volume and mass energy densities. The PCMs with different melting points and heat of fusion, including the sodium acetate trihydrate (SAT), the sodium thiosulfate pentahydrate (STP), and the disodium hydrogen phosphate dodecahydrate (DHPD), are evaluated to preheat a 3S3P 18650 battery pack from 5 °C to 20 °C. The simulation results show that the increase of the PCM thickness will decrease the preheating time and the temperature difference, but increase cell temperature and mass-energy density. The decrease of the gap can reduce the temperature difference and increase the volume energy density. Optimization case studies show that the thin PCM thickness, small gap, and DHPD demonstrate high energy density and safe thermal performance, such as case 10 (PCM thickness = 3.05 mm, Gap = 1.0 mm, PCM type = DHPD).

Organo-rhodium and -iridium complexes containing the thiosulfate (S2O32−) ligand

Reaction of the complexes [M2(μ-Cl)2(cod)2] (M = Rh, Ir) with sodium thiosulfate pentahydrate gives the dinuclear thiosulfate complexes [M2(μ-S2O3)2(cod)2]2−, which were isolated as their Ph3PCH2Ph+ salts. An X-ray structure determination on the Rh complex confirms the dimeric nature of the complex, with the two Rh(I) centres bridged by the terminal sulfurs of the thiosulfate ligands. Using ESI mass spectrometry, the dimer [M2(μ-S2O3)2(cod)2]2− and monomer [M(S2O3)(cod)]− are both observed, depending on the metal and capillary exit voltage. Reaction of sodium thiosulfate pentahydrate with the complexes trans-[RhCl(CX)(PPh3)2] (X = O or S) gave the anionic complexes Na[Rh(S2O3)(CX)(PPh3)], which were characterised by 31P{1H} NMR and IR spectroscopies, ESI MS, and in the case of the thiocarbonyl complex, by elemental analysis. Pentamethylcyclopentadienyl (Cp*) rhodium(III) and iridium(III) thiosulfate complexes [(Cp*M)2(μ -S2O3)3]2− were also synthesised by reaction of the chloride-bridged dimers [Cp*MCl2]2 with sodium thiosulfate, and isolated as their Ph3PCH2Ph+ salts. The complexes gave the expected parent dianions in ESI mass spectra, which underwent fragmentation of a thiosulfate ligand at higher capillary exit voltages to give ions [(Cp*M)2(S2O3)2S + H]−.

Ficus Capensis Modulates Oxidative Stress Parameters in Cyanide Induced Rats

The sub-acute effect of F. capensis was assessed on the oxidative stress markers in the kidney of rats following exposure to cyanide. These effects were compared to those of sodium thiosulphate (Na2S2O3), a classical antidote of cyanide toxicity. The rats were divided into 9 groups of 5 animals each. Group 1: rats (normal control); Group 2: rats were exposed to 3mg/kg of cyanide; group 3: cyanide induced rats that received 660mg/kg sodium thiosulphate pentahydrate and 6.6 mg/kg sodium nitrite; group 4 and 5: rats exposed to cyanide, pre-treated with 200 and 400mg/kg extract respectively; group 6 and 7: rats were exposed to cyanide, post-treated with 200 and 400 mg/kg extract respectively; group 8 and 9: rats exposed to cyanide, co-treated with 200 and 400mg/kg extract respectively. The study lasted for 28 days after which the rats were sacrificed and kidney homogenates were collected for biochemical assays. The level of malondialdehyde (MDA) in Groups 2 rats (367.99±17.73Units/g tissue) was significantly increased in the kidney relative to the control (148.92±4.50 Units/g tissue). This was accompanied with a decrease in antioxidant enzymes Superoxide Dismutase (SOD) (7.81±2.45 Units/g of tissue), Catalase (CAT) (34.33±1.73 Units/g of tissue), compared with the control (16.18±0.42 units/g of tissue) and 64.82±8.91 units/g tissue respectively. Pre-administration of F. capensis extract significantly increased these antioxidant extract reduced lipid peroxidation in the kidney and increased antioxidant status of animals exposed to cyanide and was more effective at 400 mg/kg dose.

Self-powered solar desalination using solar still enhanced by external solar collector and phase change material

• Performance of Solar still (SS) with solar collector (SC) and phase change material (PCM) was studied. • External SC and PCM increased the productivity by about 340%. • Increasing hot water flow from SC increased SS productivity. • The daily productivity on typical May-month/Jordan reached almost 10 L/m 2 . • The studied PCMs provided almost similar effect on productivity. The performance of a self-powered double-glass cover solar still with phase change material (PCM) connected to solar collector was studied. Black painted stainless-steel tubes filled with the required amount of PCM were placed at the bottom of the basin covering its surface area. Three modes of experiments were carried out al with cooling the glass cover: first, the solar still alone (SS), second: the solar still being connected to an external solar collector (SSC) and third: the solar still contains PCM and being connected to an external collector (SSCP). The effect of PCM type (sodium thiosulfate pentahydrate (STP), sodium acetate trihydrate (SAT) and paraffin wax (PWAX)) and its amount on the unit performance were investigated. The effect of hot water flow rate from the solar collector, solar radiation, ambient temperature and wind speed on the unit’s performance were also investigated. The novelty of the work lies in combining the above techniques and parameters to improve the still productivity under set of controllable operating conditions. The experimental work was conducted in the months of May, June and July of 2019 in northern Jordan. During May, the daily productivity of the SS and the SSC modes were found to be 2.1 and 9.7 L/m 2 . During July, the productivity was lower by 20% than that of May. The addition of PCM increased the productivity of the SSC system by about 50%. The type of PCM tested has no significant effect on the unit productivity. The addition of the external solar collector to the SS system unit increased the productivity by about 340%. The overall enhancement in productivity of SSCP reached almost 400% compared to that of SS unit.

Preparation and thermal performance enhancement of sodium thiosulfate pentahydrate- sodium acetate trihydrate /expanded graphite phase change energy storage composites

Heat energy storage using phase change materials (PCMs) in electric radiant floor heating system (ERFHS) is a favorable solution to the improvement of energy efficiency. In this paper, the sodium thiosulfate pentahydrate (Na2S2O3•5H2O,STP)- sodium acetate trihydrate (CH3COONa•3H2O, SAT) eutectic mixture was prepared by adding 30 wt.% STP and 70 wt.% SAT. Sodium carboxymethyl cellulose (CMC) and sodium pyrophosphate (Na4P2O7,TSPP) were added to fabricate the modified STP- SAT phase change material. The results showed that almost no phase separation occurred in STP- SAT eutectics with 1 wt.% CMC and 0.4 wt.% TSPP, and its supercooling degree was reduced to 0.3 °C. The thermal properties of the composite phase change material (CPCM) with different contents of expanded graphite (EG) were studied. And the experimental results showed that the composite containing 8% EG displayed a high phase change enthalpy (186.0 kJ/kg) and an ignorable supercooling degree. The addition of EG increased the thermal conductivity of STP-SAT from 0.748 to 2.92 W/m•K. The thermal reliability of CPCM was confirmed through the thermal cycle test and thermogravimetric analysis (TGA). After 200 thermal cycles, CPCM exhibited fantastic thermal stability and reliability.

A deep supercooling eutectic phase change material for low-temperature battery thermal management

Electric vehicles face the problem of battery capacity degradation in cold environment. Electric heating with thermally conductive patches and partial short-circuits could solve the problem to a certain extent but sacrifice part of the battery capacity. Here we propose a eutectic phase change material (EPCM) composed of sodium thiosulfate pentahydrate (Na2S2O3·5H2O, STP), sodium acetate trihydrate (CH3COONa·3H2O, SAT) and deionized water with a ratio of 64.4 wt%: 27.6 wt%: 8 wt%. The EPCM possesses a melting temperature of 41.4 °C, stable supercooling degree over 61 °C (storage at -20 °C), and a recovery temperature of 25.4 °C when a controllable heat release trigger is inserted. The phase change enthalpy of the EPCM is 169.29 kJ/kg. When integrating the proposed EPCM with a power battery pack (36 pieces of 18,650 power batteries, EPCM volume ratio 45%), the discharge capacity of the power battery pack at -20 °C environment can be improved by 6.8%. The effects of material composition on supercooling and recovery temperature are discussed. This study provides an alternative way in solving the battery capacity degradation in cold environment without sacrificing the energy of the battery pack and paves a way for high energy efficiency battery thermal management.

Study on Heat Transfer Process and Fresh Water Output Performance of Phase Change Heat Storage Dehumidifier

In the humidification-dehumidification solar desalination process, using phase change materials to recover water vapor condensation latent heat in the dehumidification can improve heat utilization and water production performances. When sodium thiosulfate pentahydrate and paraffin were used as phase change materials respectively in the phase change heat storage dehumidifier, by means of numerical simulation and experiment, the heat transfer process, entropy generation, and water production performances of heat pipes and copper wire meshes coupled phase change materials in the dehumidifier were studied. The results showed that sodium thiosulfate pentahydrate has stronger heat transfer ability, higher thermal entropy generation, and heat storage capacity than paraffin; adding copper wire meshes into the phase change material can accelerate heat transfer and shorten the time required for monitoring points to reach phase change temperature; increasing the wet air temperature at inlet of phase change heat storage dehumidifier, using copper wire meshes in the phase change material, increasing the diameter of copper wire mesh, and using a passive basin desalinator for secondary water production can improve water production performances. In brief, the use of sodium thiosulfate pentahydrate and copper wire meshes in the phase change heat storage dehumidifier leads to better heat storage and heat transfer effects.

Battery Thermal Management System for electric vehicles using Phase Change Materials

Electric Vehicles (EVs) owing to their relatively low emissions and noise pollution are the most suitable alternatives for conventional vehicles. Lithium-ion batteries which are widely used in Electric Vehicles are meant to operate within a strict temperature range of 20 °C–50 °C Battery Thermal Management Systems (BTMS) plays a vital role in maintaining this temperature range, improving performance, service life and safety of the battery. Conventionally, there are two categories of BTMS, namely active cooling and passive cooling. Owing to the drawbacks such as power consumption and design complexities involved in active cooling, passive cooling techniques are increasingly gaining popularity. Passive cooling using Phase Change Materials (PCMs) are excellent candidates for BTMS application. PCMs have high latent heat and can absorb a large quantity of heat generated from the battery, with minimal change in temperature. Two PCMs (n-Docosane and Sodium Thiosulfate Pentahydrate) were chosen based on their properties such as melting temperature, Latent heat, Specific heat, Thermal Conductivity, Dynamic Viscosity and Density. This article also provides a methodology to optimize the usage of PCM for BTMS applications. While excess usage of PCM will add to the battery’s weight and also lead to ineffective use of PCM, using insufficient amount of PCM might lead to uncontrolled rise in cell temperature. This objective can be achieved by observing the trends of two specific output parameters – Mean Cell Temperature and Liquid Fraction derived from computational methods.

The impact of two commonly used neutralizing agents in water sampling bottles on legionella and pseudomonas bacteria recovery

Microbiological monitoring may be indicated by the local risk assessment of hospital water systems. When water sampling is carried out, it is imperative that the activity of any residual biocide is completely neutralized. Sodium thiosulphate pentahydrate (Na₂S₂O₃·5H₂O) is commonly used to neutralize oxidizing biocides in water samples for microbiological testing. Ethylenediaminetetraacetic acid dihydrate (Na2EDTA.2H2O) is recommended to neutralize silver-copper ionization treated water samples. However, there are inconsistencies in the recommended effective concentration. Furthermore, sampling bottles dosed with Na2EDTA.2H2O are not commercially available. To investigate the efficacy of Na2EDTA.2H2O as a neutralizing agent compared with sodium thiosulphate (Na₂S₂O₃·5H₂O) on water samples treated with silver and copper ions and to assess the biocidal activity in water samples. An interlaboratory investigation was carried out using simulated water samples spiked with Legionella pneumophila or Pseudomonas aeruginosa with and without silver and copper ions. Bacterial recovery was determined in sterile sampling bottles dosed with either 50 mg/L Na2EDTA.2H2O or 180 mg/L Na₂S₂O₃·5H₂O as the chemical biocide neutralizing agent. Na₂S₂O₃·5H₂O effectively complexed both silver and copper ions and inhibited biocidal activity. The 50 mg/L of Na2EDTA.2H2O continued to demonstrate significant biocidal activity in the spiked samples. This study demonstrated that Na2EDTA.2H2O is not an efficacious neutralizing agent on water samples treated with silver and copper ions. Sample bottles dosed with 180 mg/L Na₂S₂O₃·5H₂O were more effective in neutralizing silver and copper ions generated in water that had been treated by silver-copper ionization systems.

Discharging performances of supercooled CH3COONa·3H2O and Na2S2O3·5H2O in the rounded rectangular unit and parametric analysis

Discharging performances of supercooled salt hydrate PCM (phase change material) in the rounded rectangular storage unit are numerically investigated with the developed multiphase model. Comparisons are first made between supercooled Sodium acetate trihydrate (SAT, CH3COONa·3H2O) and Sodium thiosulfate pentahydrate (STP, Na2S2O3·5H2O). Effects of environment temperature for storage (t0), temperature of the working fluid (tf), the area – volume ratio of the unit (A/V) and PCM thermal conductivity are then analyzed. The results showed that STP has 8% less loss of latent heat during the triggering crystallization process whereas lower discharging rate than SAT due to the lower melting point. Decreasing t0 from 14 °C to 6 °C results in 9% more latent heat loss; decreasing tf from 38 °C to 30 °C also shortens the time period for heat release from 4h to 1.8h; higher A/V and k lead to the higher heat transfer rate, for A/V =200 m−1, the discharging time is 4.2h shorter than that for A/V =70 m−1; however, the effect of k is negligible when k is over 1 W m−1 K−1 due to the larger thermal resistance on the side of working fluid. The results provide guidance for design and application of supercooled SAT and STP in rounded rectangular units for energy storage in solar heating systems.

Experimental investigation on discharging characteristics of supercooled CH3COONa·3H2O-Na2S2O3·5H2O mixtures triggered by local cooling with Peltier effect

Latent heat stored in the supercooled salt hydrate liquid can be released at the desired time by triggered crystallization. In this paper, the melted sodium acetate trihydrate (SAT, melting point Tm = 55.7 °C) and sodium thiosulfate pentahydrate (STP, Tm = 48.9 °C) are cooled by natural convection of room air with respective supercooling degrees of 33 °C and 28 °C. Experiments are performed on the effect of local cooling by semiconductor refrigerator on triggering crystallization of supercooled SAT, STP and their binary mixtures with different mass ratios. The results show that SAT has higher discharging temperature and longer discharging time than STP; but STP has less phase separation, better cycling stability and shorter induction period during the crystallization than SAT after repeated melting-freezing cycles. Moreover, the phase separation problem of SAT could be significantly alleviated with the addition of STP. With the increase of SAT content in the SAT-STP mixtures, the induction period during the crystallization tends to firstly increase and then decrease. The tested curve of the maximum discharging temperatures presents as a V-shaped trend and roughly corresponds with the binary phase diagram. The eutectic mixture of SAT-STP (mSAT:mSTP = 28:72, the eutectic temperature of 40.8 °C) can be triggered in 4 min and shows a discharging temperature peak measured at 39 °C. The discharging time of 3.3 h with temperature above 30 °C is longer than that of single-component salt hydrates. The obtained results are helpful for system design and practical application of solar energy storage based on supercooled phase change materials.

The effect of sodium thiosulfate in a culture medium on the sexual reproduction of three species of Bacillariophyta

It was studied the effect of sulfur in the form of sodium thiosulfate pentahydrate on the capability of clonal cultures of Pleurosigma sp., Toxarium undulatum, Pseudo-nitzschia calliantha to interbreed successfully and produce fertile offspring if they were cultivated in artificially prepared marine water (ESAW medium). Differences in the time of the beginning of the sexual process and the intensity of its passage for clones contained on ESAW with the addition of sodium thiasulfate and in the absence of it are shown.

Monitoring the Presence of Bacteria, Fungi and Parasitic Pathogens Associated with Swimming Pools in Port Harcourt Metropolis

Aims: Ideal water for swimming should meet the portable water standard by being transparent, odorless, and tasteless. However, these qualities can be affected by the presence of infectious agents which directly or indirectly contaminate pool water. This study aims at monitoring the microorganisms (bacteria, fungi and protozoa parasites) and pH associated with swimming pool water.
 Study Design: A random sampling technique was adopted to select the five (5) swimming pools for the study based on accessibility and visitation.
 Place and Duration of Study: The study was carried out in Port Harcourt Metropolis, Port Harcourt Local Government Area, Rivers State between March 2016 to August 2017.
 Methodology: Five (5) outdoor swimming pools attached to hotels in Port Harcourt Metropolis, Port Harcourt Local Government Area of Rivers State, Nigeria were randomly selected for the study. Water samples were aseptically collected in duplicates and analyzed for total heterotrophic bacterial count, total heterotrophic fungal count, protozoa and pH using appropriate techniques.
 Results: The results show that swimming pools with sodium thiosulphate pentahydrate had a mean THBC range from 4x101 cfu/ml - 1.58x103 cfu/ml, mean THFC, 0 cfu/ml - 8x101 cfu/ml and mean pH, 5.9-6.4; for samples without sodium thiosulphate pentahydrate, the mean THBC ranged from 0 cfu/ml - 9.2x101 cfu/ml, mean THF, 0 cfu/ml - 8x101 cfu/ml and mean pH, 5.6-6-2. Protozoa (parasites) were absent in all water samples analyzed. The results further reveals that 95.9% and 100% of the swimming pools samples failed to the meet the <100 cfu/ml and 7.0 – 7.8 World Health Organisation Standards for THBC and pH respectively. The bacteria identified are Bacillus spp., Escherichia coli, Stapylococcus aureus while the fungi identified are Aspergillus spp., Rhizopus spp. and Penicillium spp.
 Conclusion: The study finds the levels of THBC in the samples with sodium thiosulphate pentahydrate, the presence of Escherichia coli and the pH range a threat to health of bathers. Therefore, the owners should ensure routine decontamination and assessment of water quality.

Theoretical modeling of a glass-cooled solar still incorporating PCM and coupled to flat plate solar collector

Abstract The performance of a modified solar still was investigated considering the following cases: solar still with glass cooling (SC), SC connected to an external collector (SCC), and SCC with phase change material (SCCP). Three different PCMs were used; sodium acetate trihydrate, sodium thiosulfate pentahydrate, and paraffin wax. The effect of various parameters; controllable (hot water circulation rate, PCM mass, and cooling water flowrate) and uncontrollable parameters (solar irradiation, ambient temperature, and wind speed) were investigated. Increasing the solar irradiation from 200 to 700 W/m2 increased the productivity from 0.9 to 3.4, 2.35 to 10, and 3 to 11.9 ml/min for the SC, SCC, and SCCP (with SAT as PCM) systems, respectively. The addition of external collector and PCM increased the productivity 2.4 times. Increasing the coolant mass flow rate from 0 to 10 kg/s, increased the productivity from 1 to 2.14, 1 to 6.65, and 1 to 7.5 ml/min for the SC, SCC, and SCCP systems, respectively. Additionally, increasing the hot water circulation rate of external collector from 0 to 0.1 kg/s increased the productivity from 2.4 to 6 and from 4 to 7.4 ml/min for SCC and SCCP system, respectively. The optimum mass ratio of basin water: PCM was found to be 2:1, while the best PCM type was found to be the one with the highest melting point and latent heat of fusion. The 24-h operation for a typical May month weather data in Jordan, revealed that the productivity improved 1.8 times for SCC and 2.3 times for SCCP-SAT compared with SC system.