In the present work a polymer with phosphonium pendant groups impregnated with crown ether (dibenzo-18-crown-6) and loaded with iron ions was investigated for arsenic removal through adsorption from aqueous solutions. The impregnated polymer was loaded with iron ions due to the high affinity of arsenic to it. The characterization of the surface modification of the obtained new adsorbent material was performed on the basis of energy dispersive X-ray analysis; scanning electron microscopy and Fourier transform infrared spectroscopy. The arsenic adsorption was investigated, including effect of pH, arsenic initial concentration, the shaking time and temperature. The effect of the pH was examined over the range 2-11. The adsorption of As(V) increases with pH increasing reaching a maximum at pH higher than 8. Equilibrium, kinetic and thermodynamic studies were carried out to study the adsorption performance of the obtained material in the removal process of arsenic from aqueous solutions. For the studied materials the equilibrium data closely fitted Langmuir model and was achieved a maximum adsorption capacity of 32.6 μg As(V)/g of material. The pseudo-second order kinetic model is suitable for describing the adsorption system. The obtained results show that the studied adsorbent can be used with efficiency in the arsenic removal from underground water even from low influent arsenic concentration solutions.

The objective of this paper was to evaluate the potential of a new adsorbent material to recover Au (III) from real wastewater, in a column with a fixed bed in a dynamic regime. The material was obtained through functionalization, by impregnation of the commercial resin, Amberlite XAD 7 type, with L-glutamic acid, which has active groups –NH2 and –COOH. The goal of the experiments was to follow the correlation of fixed-bed column specific adsorption parameters (the effluent volume, the amounts of adsorbent, heights of the adsorbent layer in column) with the time necessary to cross the column. The experimental data obtained were modeled, using the Bohart–Adams, Yoon–Nelson Thomas and Clark models, to establish the mechanism of the Au (III) recovery process, in a dynamic regime. Also, we established the number of cycles for adsorption–desorption for which the new material can be used. We used 5% HNO3 (5%) as desorption agent in five adsorption–desorption cycles, until the process was no longer efficient. The degree of desorption varied between 84% and 34% from cycle 1 to cycle 5.

The aim of this paper was to produce a new composite material based on carbon and iron oxides, starting from soluble starch and ferric chloride. The composite material was synthesized by simple thermal decomposition of a reaction mass obtained from starch and iron chloride, in an inert atmosphere. Starch used as a carbon source also efficiently stabilizes the iron oxides particles obtained during the thermal decomposition. The reaction mass used for the thermal decomposition was obtained by simultaneously mixing the carbon and iron oxide precursors, without addition of any precipitation agent. The proper composite material can be obtained by rigorously adhering to the stirring time, temperature, and water quantity used during the preparation of the reaction mass, as well as the thermal regime and the controlled atmosphere used during the thermal decomposition. Synthesized materials were characterized using thermogravimetric analysis, X-Ray Diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infra-red spectroscopy (FT-IR). The performances of the obtained material were highlighted by studying their adsorbent properties and by determining the maximum adsorption capacity for arsenic removal from aqueous solutions.

One of the main goals of the World Health Organization (WHO) and its Member States is that "all people, regardless of their stage of development and their social-economic condition, have the right to have access to adequate drinking water". The problem of remediation of waters contaminated with toxic substances, using natural resources, is a special concern at a high level. Researchers' efforts have sought to find effective and cheap ways to reduce the impact on the environment. As(III) gets into the environment from a variety of natural and anthropogenic sources. As As(III) is commonly found in rocks, soil or sediments, these sources are particularly important determinants of the As(III) zonal level in groundwater and surface water. As(III) contamination is currently one of the major problems with serious consequences on the biosphere. The main objective of this paper is the establishment of a method for the removal of As(III) from real waters by adsorption in a fixed bed column, using ecological materials, friendly to the environment. For this reason, the content of As(III) in groundwaters in the Romania-Hungary border area was determined, knowing the fact that the Pannonian Basin was given special attention, being an area heavily affected by As(III) contamination of natural water sources. The paper studies the adsorption of As(III) from a natural water taken from the monitored area. At the same time, it has followed the behaviour of microorganisms naturally existing in the soil of Timisoara city and in the Bega river in the presence of different amounts of As(III) in order to establish the relative toxicity of As(III) in them.

The focus of this study is purifying the wastewater from the lacquers and paint industry in Western Romania, containing different organic compounds.The organic load in wastewater is found in the form of various organic compounds. Nonpolar organic substances lighter than water form a layer that blocks the flow of oxygen necessary, while polar substances are soluble in water and can be toxic to the fauna or create the effect of eutrophication causing disequilibrium in the biotope.In this paper we aimed at eliminating these organic compounds from wastewater by physical-electrocoagulation and chemical-oxidation methods to ensure a high degree of removal of these compounds to discharge into the sewage. The wastewater was characterized before and after the treatment following a series of quality indicators (chemical oxygen demand COD, total organic carbon TOC, lead Pb(II), cadmium Cd(II), chrome total Crtot, copper Cu(II), nickel Ni(II), zinc Zn(II), manganese Mn(II)). The total organic carbon analysis (TOC) was performed before and after the treatment to determine the total content of organic compounds.The resulting sludge from the wastewater contaminated with organic compounds treatment was subjected to thermal analysis.