Treatment of ammonia in waste air using packed column coupling with chemical reaction

Ammonia is a common chemical used in various industries. Emission of air contaminated with ammonia to the atmosphere without any treatment causes several effects on human health and environment.A high efficiency method for ammonia removal from waste air is then necessary. In this research, an absorption coupling with chemical reaction was investigated for ammonia removal from waste air using a packedcolumn. The packed column of 10 cm diameter and 200 cm height was packed with 1.4x1.4 cm Raschig rings. Three liquids including water, NaOCl and H2SO4 solution were used as an absorbent for the investigation.The objectives of this research were to determine a suitable absorbent and the optimum condition for ammonia removal from waste air. The packed column was operated at room temperature and atmosphericpressure. The tested conditions were as follows: the gas to liquid ratio (G:L ratio) was 35-90 m3 gas/m3 liquid, the inlet concentration of ammonia was 150-500 ppm and the air flow rate was 18 m3/h. The results showedthat the ammonia removal efficiency depends on type of the absorbent and the operating condition. The efficiencies increased with decreasing of G:L ratio and with increasing absorbent concentration. They were70%, 80-92%, and 95-100% for pure water, sodium hypochlorite solution and sulphuric acid solution, respectively. The efficiency decreased with time when water was used as an absorbent while it was almostconstant when NaOCl and H2SO4 solution were applied. The ammonia removal efficiency when using H2SO4 as the absorbent was not dependent on G:L ratio and inlet ammonia concentration, in the range used in thisinvestigation. Since H2SO4 solution gave the highest removal efficiency and can reduce ammonia concentration in waste air to levels which meet the TLV-TWA standard, it is recommended as an absorbent solution forammonia removal from waste air

Biodiesel production from palm oil

Methyl ester was produced from many sources of oil palm products, namely used frying oil, RBD palm oil, degummed and deacidified palm oil, palm stearin and superhard palm stearin. Production process was a conventional transesterification batch process using methanol as reactant and sodium hydroxide as catalyst. Production procedure consisted of oil preparation, solvent preparation, reaction step, glycerol separation, washing step and finishing step. Thin layer chromatograph was used to determine the composition of product and nearly 100% methyl ester was obtained at a suitable condition. Molar ratio of oil: methanol was about 1:6, which equal to 20% by weight of methanol. Sodium hydroxide was 0.5-1 %wt. of oil. The production temperature was 60-80ºC, mixing time was only 15-30 minutes and reaction time was 3-4 hours. Many fuel properties of methyl ester were very close to high-speed diesel such as viscosity, density, heating value and boiling point range. Pour point of methyl ester was higher than diesel owing to the high composition of saturated methyl ester that has a high melting point

Mass transfer coefficient for volatilization of volatile organic compounds from wastewater

Volatilization of volatile organics compounds (VOCs) from wastewater is recognized as an important source that caused air pollution today. In air pollution management regarding VOCs emission to atmosphere, the amount of VOCs that released from wastewater needs to be known. A model for predicting of VOCs volatilized from wastewater is then necessary. The aim of this research was to develop the gas-film (kGa,VOC) and liquid-film (kLa,VOC) mass transfer coefficients from volatilization of VOCs from wastewater. The volatilization experiments were performed in a pilot volatilization tank with a volume of 100 L. The wind speed over the water surface, measured at 10 cm above water surface (U10cm), was the main parameter which investigated in this work. The U10cm were varied from 0 to 4.42 m/s. VOCs used in this investigation were methanol, toluene and methyl ethyl ketone.The results revealed that the gas-film coefficient of methanol increased linearly with increasing U10cm over the investigated range of U10cm whereas the liquid-film coefficient of toluene fell into two regimes with a break at the U10cm of 2.4 m/s. The correlations of kGa,VOC and kLa,VOC were developed from gas-film and liquid-film coefficient of methanol and toluene, respectively, and verified by predicting overall mass transfer coefficient (KOLa) of MEK. It was found that the correlations of kGa,VOC and kLa,VOC predicted the mass transfer coefficient of MEK which volatilized from wastewater quite well but underestimated KOLa of MEK volatilized from pure water. Since the mass transfer coefficient of VOCs volatilized from pure water were significant higher than that of wastewater as found in this work, the kGa,VOC and kLa,VOC developed based on wastewater is recommended for prediction of VOCs emission rate from wastewater rather than the correlation previously developed based on pure water

Simple model for the prediction of ammonia volatilization from water basin: effect of water temperature and pH

Ammonia is a primary chemical used for preserving rubber latex. Consequently, the wastewater from concentrated rubber latex processing contains high ammonia concentration. The volatilization of ammonia from such wastewater may cause an air pollution problem such as the formation of an acid rain or an aerosol of ammonium nitrate and ammonium sulfate, which can seriously affect environment and human being. To assess the air pollution problem regarding atmospheric ammonia volatized from wastewater, the model for the prediction of ammonia volatilization rate and flux is therefore desirable. The purposes of this study were to investigate the effects of water temperature and pH on ammonia volatilization process and to develop a model to describe ammonia volatilization rate and flux including such effects.Ammonia volatilization from water was studied by using a volatilization tank (surface area = 780 cm2, volume = 7 L) placed in a water bath in order to control the water temperature. The temperature and pH in the range of 25 to 50ºC and 5 to 11 were respectively investigated. The overall mass transfer coefficients of ammonia were measured as a function of temperature and pH. The quadratic multiple regression technique was used to obtain the model for mass transfer coefficient from experimental data. The model suggests that the overall mass transfer coefficient of ammonia increases with increasing water temperature and pH while the temperature-pH interaction retards the increasing characteristic of mass transfer coefficient. Thus the increasing in mass transfer coefficient at higher temperature and pH was slower than that at the lower one. The simple model for the prediction of ammonia volatilization rate and flux was developed based on mass transfer theory and mass transfer coefficient model obtained from this study. This simple ammonia emission model can be used to predict ammonia volatilization rate and flux at any pH, water temperature and ammoniaconcentration in water