Abstract:Natural minerals from different localities in the Republic of Macedonia are selected for elimination of Cr(VI) ions from water resources. For that aim are selected: aksil (Kriva Palanka), trepel (Bitola), SiO 2 amorphous (Kozuf), pemza (Bojanciste). In this study, their adsorption capacity is analyzed using spectrophotometric method (UV/VIS Spectrophotometer). Results from the spectrophotometric analysis in all used examples gave us insight for the starting concentration of Cr(VI) before adsorption and concentration after adsorption. The physical, chemical and mineralogical characteristics of adsorbents are studied. XRD, TGA-DTA and FT-IR analysis are used for characterization of natural mineral materials. The surface area of the sorbents were measured by BET method. With aim to determine the optimum pH value for maximal removal of Cr(VI) ions, the point of zero charge, pH PZC , for investigated materials were obtained. The aim of the study is to select which adsorbent is more effi cient for elimination of Cr(VI) from water resources. According to obtained results all of them were successful in elimination of Cr(VI), but more effi cient and economic is trepel.
The results of the water retention curves between (pF -2 and -4.2) matric potential for two substrates perlite and peat, are presented in this paper. Perlite is an inorganic, expanded aluminosilicate of volcanic origin. Peat is an organic substrate. For assessing this parameter, the method of bar extractors and Porous plate extractors have been explored. The method is applied on 7 different regimes of pressure (0.1; 0.33; 1; 3; 6.25; 11; 15 bars) in samples composed of perlite and peat present at different volume ratios of 80% Perlite + 20% Peat, 70%Perlite + 30% Peat, 50% Perlite + 50% Peat, 30% Perlite + 70% Peat, 20%Perlite + 80% Peat. The retention capacity of the pеrlite, at all applied different point of tension, is: 67.88% for 0.1 bar, 58.35%, for 0.33 bar, 47.70% for 1 bar, 39.78%; for 3 bars, 34.84 for 6.25 bars, 30.10% for 11 bars and 26.65% for 15 bars and for the peat are: for 0.1 bar = 89.16%, for 0.33 bar = 74.84%, for 1 bar = 57.94%; for 3 bars = 45.15%; for 6.25 bars = 39.57; for 11 bars = 33.89%; for 15 bars = 23.17%. The peat substrate shows higher retention at all points of tension of 0.1; 0.33; 1; 3; 6.25; 11, with the exception of 15 bars, when the retention is lower than the substrate perlite.The reason for the higher water retention at peat than at perlite, is the result of the high content of the humus in the peat. Of all the analyzed samples, it can be seen that all curves show a favorable water retention capacity, which is due to the fact that the peat and the perlite as substrates have high porosity. The aim of this paper is to examine the impact of the water retention capacity of both substrates and their mixtures. Also to see the ability which substrate retains a greater amount of water that will be easily accessible to the plants for their proper growth and development.
Abstract:The novel trends in green separation processes impose the need for application of natural, low-cast and high-effi ciency selective adsorbents, such as natural zeolite, within the processes for the treatment of drinking water supplies. Lately, nano-porous inorganic sorbents represent an ongoing trend for elimination of heavy metals from water resources. In the frame of this work, the nanoporous material, clinoptilolite,was applied for removal of Ni(II) ions fr om water resource. The experimental results were obtained in a laboratory scale batch glass reactor with continuous stirring at 400 rpm. The effects of the mass of the nano-porous adsorbent and the initial pH of the solution were studied to optimize the conditions for maximal removal of Ni(II) ions. MATLAB/Curve Fitting Toolboxwas implemented to determine the adequate adsorption isotherm as well as to optimize the equilibrium state of the investigated system.
The mosquitoes are a serious threat to public health, since they are known vectors of many life-threatening diseases. Mosquito-borne diseases cause millions of deaths worldwide every year. While mosquitoes are important to maintain ecosystems, the aim is to keep them out of our personal space. People looking for alternatives to synthetic mosquito repellents may find that some natural repellents are effective in protecting them from bites. Natural insect repellents use natural ingredients such essential oils and other plant-based elements. Certain essential oils are effective and helpful in repelling mosquitoes, and are a natural alternative to the harsh chemicals in commercial bug sprays. These products are also likely to be less toxic to humans and the environment. Natural repellents and some essential oils may be effective in keeping mosquitoes away because they block their sense of smell. Many natural scents that are appealing to humans actually repel mosquitoes. Plant - based repellents are becoming more widely used as a protecting measure against mosquito bites, but more research is needed to develop natural repellents in terms of improving their repellent efficiency as well as in terms of their safety for use. This article presents a review about the best essential oils used as green repellents against mosquito bites, their efficiency, development and testing.
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