Abstract:In order to investigate the mechanism of adsorption of reactive dyes from the textile industry on ash from heating plant produced by brown coal combustion, some characteristic sorption constants are determined using Langergren adsorption equations for pseudo-fi rst and pseudo-second order. Combined kinetic models of pseudo-fi rst order and pseudo-second order can provide a simple but satisfactory explanation of the adsorption process for a reactive dye. According to the characteristic diagrams and results of adsorption kinetic parameters of reactive dyes on ashes, for the applied amounts of the adsorbents and different initial dye concentrations, it can be concluded that the rate of sorption is fully functionally described by second order adsorption model. According to the results, the rate constant of pseudo-second order decreases with increasing initial dye concentration and increases with increasing amount of adsorbent -ash.
An adsorption process using cheap adsorbents could be described as a simple, selective and low cost alternative for the treatment of colored waste water compared to conventional physical and chemical processes. In this study the use of a natural waste adsorbent - ash was investigated for the removal of a textile vat dye Ostanthren Blue GCD remaining after the dyeing of cotton textile. The ash obtained as a waste material during the burning of brown coal in the heating station of Leskovac (Serbia) was used for the treatment of waste waters from the textile industry, i.e., waste water after the dyeing process. The effect of ash quantity, initial dye concentration, pH and agitation time on adsorption was studied. The Langmuir model was used to describe the adsorption isotherm. Based on the analytical expression of the Langmuir model, the adsorption constants, such as adsorption capacity and adsorption energy, were found. Pseudo first and second order kinetic models were studied to evaluate the kinetic data.
Nitrogen compounds are essential elements for living organisms. The increased concentration of ammonia in ionized (NH 4 + ) and non-ionized form (NH 3 ) in surface waters causes negative effects on aquatic organisms, since it enters into the nitrogen cycle, and thus contributes to the eutrophication of water. The presence of higher concentrations of ammonia in surface waters than natural ones is the result of faecal contamination through the sewage system or runoff from arable areas which were treated with fertilizer. Water contaminated with ammonia can be purified by various methods: biological (nitrification-denitrification method), oxidation with chlorine, chemical precipitation, membrane filtration, etc. One of the alternative methods is removal by adsorption with natural materials such as clay and zeolite. Bentonite clay was marked off as a suitable adsorbent of cationic pollutants due to the permanent negatively charged surface. Тhe textural properties (specific surface, porosity) and structural properties of bentonite clay (the distance between the layers, the type of ions in the space between the layers) and consequently its adsorption capacity for pollutants is changed with the activation by acid or base and intercalation. There is very little literature data on the application of bentonite clay for removal of ammonium ions. Therefore, the aim of this work is activating the raw bentonite clay with a base and its application as an adsorbent for removal of ammonium ions from aqueous solutions. The influence of the adsorption conditions (adsorbent dose, temperature, pH, adsorbate concentration and contact time) on the amount of removed ammonia from the aqueous solution was investigated. Equilibrium data were analyzed by Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The best agreement with experimental data was obtained by Langmuir isotherm (R 2 = 0.987). The following kinetic models were applied: the pseudo-first order, pseudo-second order, and the intra-particle diffusion model. The pseudo-second order model is most suitable for describing the adsorption of ammonium ions onto the base activated bentonite from aqueous solutions (R 2 = 0.997). Removal of ammonium ions by activated clay is a pHdependent and endothermic process, the adsorption degree of pollutants is increased with rising temperature. The highest adsorption capacity of the base activated bentonite clay of 26.82 mg/g was obtained in a solution of pH 6 and a temperature of 40 °C, at an adsorbent dose of 2 g/dm 3 and аt an adsorbate concentration of 100 mg/dm 3 . By activating the adsorbent in a 1 M NaOH solution, the adsorption ability of the bentonite clay towards ammonium ions is improved. The results of this study show that the base activated bentonite clay is a potential adsorbent material for ammonia, i.e. ammonium ions. 1254 Слика 2. Зависност адсорбоване количине амонијум јона базно активираном бентонитном глином од температуре (а) и pH вредности (б)Највећи адсорпциони капацитет глине у испитиваном опсегу pH вредности (2-10) за...
The textile industry is one of the biggest industrial consumers of water especially dye houses which utilize synthetic dyes and other chemicals. Natural dyes are generally environmental friendly and have many advantages over synthetic dyes with respect to production and application. In recent years, there has been an interest in the application of these dyes due to their bio-degradability and higher compatibility with the environment. A review of previous work in the field of applying dyestuffs of natural source as possible textile dyes is given. From an ecological viewpoint, the substitution of chemical dyes by 'natural products' in textile dyeing may be feasible and may represent not only a strategy to reduce risks and pollutants, but also an opportunity for new markets and new businesses which can develop from the inclusion of ecology in trade policy
The protection of the environment and people’s health from negative influences of the pollution of air as a medium of the environment requires constant observing of the air quality in accordance with international standards, the analysis of emission and imission of polluting matters in the air, and their connection with the sources of pollution. Having in mind the series of laws and delegated legislations which define the field of air pollution, it is necessary to closely observe these long-term processes, discovering cause-and-effect relationships between the activities of anthropogenic sources of emission of polluting matters and the level of air degradation. The relevant evaluation of the air quality of a certain area can be conducted if the level of concentration of polluting matters characteristic for the pollution sources of this area is observed in a longer period of time. The data obtained by the observation of the air pollution are the basis for creation of the recovery program of a certain area. Leskovac is a town in South Serbia where there is a bigger number of anthropogenic pollution sources that can significantly diminish the air quality. The cause-and-effect relationship of the anthropogenic sources of pollution is conducted related to the analysis of systematized data which are in the relevant data base of the authorized institution The Institute of Public Health, for the time period between the year of 2012. and 2017. By the analysis of data of imission concentrations of typical polluting matters, the dominant polluting matters were determined on the territory of the town of Leskovac, the ones that are the causers of the biggest air pollution and the risk for people’s health. Analysis of the concentration of soot, sulfur dioxide and nitrogen oxides indicates their presence in the air of Leskovac town area in concentrations that do not exceed the permitted limit values annually. The greatest pollution is caused by the soot content in the air, especially in the winter period when the highest number of days with the values above the limit was registered. By perceiving the influence of natural and anthropogenic factors, it is clear that the concentration of polluting matters can be decreased only by establishing control over anthropogenic sources of pollution, and thus it can be contributed to the improvement of the air quality of this urban environment.
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