This study is on the effect of salinity on evaporation from water bodies and probable influence on the water cycle. Five different salts were used in this study, different concentrations of Magnesium Sulphate, Sodium Hydroxide, Sodium Chloride, Ammonium Chloride and Potassium Nitrate solutions in the neighbourhood of 0.04, 0.08, 0.12, 0.16, 0.20 and 0.24 g/cm3 were prepared by dissolving 20, 40, 60, 80, 100 and 120 g weights of these salts in 500 cm3 of distilled water. The first evaporation can contained only 500 cm3 of distilled water and served as the control experiment. The solutions were introduced in evaporation cans each of capacity 700 cm3, stored under room temperature and evaporation allowed to take place. Evaporation from the cans were measured at 24 hours intervals for a period of 14 days. Results showed that in all salts, as salinity increases, evaporation is reduced. On the 10th day, evaporation retardation factors for Magnesium Sulphate, Sodium Hydroxide, Sodium Chloride, Ammonium Chloride and Potassium Nitrate were found to be 0.800, 0.490, 0.712, 0.820 and 0.822 respectively. Ratios of evaporation retardation factors were 1:1.6327 for Sodium hydroxide : Magnesium Sulphate; 1:1.4531 for Sodium Hydroxide : Sodium Chloride; 1:1.6735 for Sodium Hydroxide : Magnesium Sulphate; 1:1.4531 for Sodium Hydroxide: Sodium Chloride; 1:1.6327 for Sodium Hydroxide : Ammonium Chloride and 1:1.6776 for Sodium Hydroxide : Potassium Nitrate solutions. Highest evaporation took place in Potassium Nitrate solution at the ultimate concentration of 0.24 g/cm3, this was followed by Ammonium Chloride, Magnesium Sulphate, Sodium Chloride and Sodium Hydroxide. These salinity effects will impact on the outflow parameter in the water cycle with consequent reduction in evaporation which reduces precipitation, hence the formation of rain in the cloud would be inhibited and ultimately lead to climate change.
Efficiencies of sedimentation tanks with horizontal and vertical baffle mixers were studied, compared, and also to determine the optima values of factors of clarification in the sedimentation tanks. These are the discharge, basin baffle spacing and dosing factors, thereby comprises three factors at five levels for a 5k factorial design model. 2.0 mg/l of clay solution was introduced into the basin at discharge rates of 48.75 ml/s, 55.07 ml/s, 60.34 ml/s, 62.45 ml/s and 63.27 ml/s respectively. Alum solution was introduced as coagulant at the inlet of the basin, samples were collected both from the basin and the outlet and concentrations of flocs were measured. Plots of variation of total outlet and average outlet floc with dosing rates for horizontal and vertical mixers show that vertical mixers are better only at discharge of 48.75 ml/s, but horizontal mixers are better at 55.05 ml/s, 60.34 ml/s, 62.45 ml/s and 63.27 ml/s. Variation of grand total floc with dosing rates is also in favour of horizontal mixers. Plots of outlet floc against dosing rates at 48.75 ml/s discharge show that horizontal mixer spaced at 100 mm is better with maximum sediment/floc of 333 10-4 g at a dosing rate of 0.55 ml/s, at 55.07 ml/s discharge vertical mixer is better with 250 mm spacing giving maximum sediment of 985 10-4 g at a dosing rate of 0.95 ml/s. For 60.34 ml/s discharge, horizontal mixer is better at 250 mm spacing with maximum sediment of 307 10-4 g at 0.75 ml/s dosing rate. In the case of 62.45 ml/s discharge, horizontal mixer at a spacing of 300 mm is better with a maximum deposit of 335 10-4 g at a dosing rate of 0.95 ml/s, and for discharge of 63.27 ml/s, horizontal mixer is better at 150 mm spacing having a maximum sediment of 715 10-4 g for a dosing rate of 0.35 ml/s. Response surface methodology (RSM) presented by Montgomery, 2008 was further used for the analysis of data in this study for more reliable inference because it optimized the responses of these three variables. It was observed that for the vertically placed baffles, the stationary points of response surface for discharge rate, baffle spacing and dosing rate are 80.56762847 ml/s, 100.00000 mm and 0.04965779 ml/s, while for horizontally placed baffles, it was 70.636018 ml/s, 332.864704 mm and 1.402526 ml/s, however, these results indicate that horizontally placed baffle mixers are better than vertically placed baffle mixers.
The need for humidity sensors in various fields have led to the development and fabrication of sensors for use in industries such as the medical, textile, and laboratories. This chapter reviewed humidity sensors, major types and applications with emphasis on the optical fiber, nanobricks, capacitive, resistive, piezoresistive and magnetoelastic humidity sensors. While optical fiber sensors are best for use in harsh weather conditions, the nanobricks sensors have excellent qualities in humidity sensing. Capacitive sensors make use of impedance and are more durable than the equivalent resistive sensors fabricated with ceramic or organic polymer materials and have short response and recovery times which attest to their efficiency. Piezoresistive sensors have fast response time, highly sensitive and can detect target material up to one pictogram range. Magnetoelastic sensors are very good and can measure moisture, temperature and humidity between 5% and 95% relative humidity range. It was concluded that sensors have peculiar applications.
Rice husk adsorbent was studied to assess its efficiency in adsorption of nickel from paint industry effluent and to derive vital parameters that would assist in making timely decisions in tertiary treatment of wastewater. Standard methods were used in conducting the experiments. Results showed that significant adsorption of 84.77% of nickel was removed by carbonized rice husk (CRH) in 10 minutes and 98.42% in 60 minutes, a difference of 13.65%. Optimum pH of 8 was observed as 98.91% of nickel was adsorbed. Slight change in the adsorption efficiencies was noticed between 0.2 g and 0.4 g doses of CRH adsorbent, but reasonable and insignificant change occurred between 0.4 g and 1.0 g doses. Langmuir isotherm plot showed that separation factor was 0.998 an indication of favorable adsorption and a good fit for the Langmuir isotherm model. Therefore, the adsorption process was better described by the Langmuir equilibrium isotherm model. Adsorption intensity of 2.02 was observed in the Freundlich model, a value greater than 1.0 an indication of unfavorable adsorption. Lagergren pseudo first- and second-order plots showed that R2 = 0.799 for pseudo first-order and R2 = 0.969 for pseudo second-order reactions, an indication that adsorption of nickel by CRH follow Lagergren second-order kinetic. FTIR spectra identified N-H, O-H, C=H, C=O, C=C-C, C-Cl, P-O-C, and cis-C-H out-of-plane bend stretching bands as the functional groups involved in nickel adsorption by CRH adsorbent. It was concluded that rice husk is a good adsorbent in tertiary treatment of wastewater.
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