Mineral-carbon sorbents based on post-decarbonization lime and mixture of hydrocarbons

Summary An attempt was made to obtain mineral-carbon sorbents from waste products of petrochemical industry: lime from the decarbonization of river water to be used in technology and hydrocarbon wastes obtained in the treatment of industrial waste waters. The sorbents were prepared by thermal decomposition of mixtures of the mineral and carbon components. In order to optimize the preparation conditions, physicochemical studies were performed of both the mineral matrix and the mineral-carbon sorbents. Adsorption measurements involving nitrogen, water, and benzene as adsorbates were used for determining the parameters of porous structure of the obtained materials and their hydrophilic-hydrophobic properties. The properties influencing the sorptive properties of the organic compounds present in the petrochemical wastes were pointed out.     

城市生活垃圾焚烧体系化学热力学平衡分析

采用化学热力学平衡分析方法，分析城市生活垃圾焚烧体系污染物的排放特性。主要计算了聚氯乙烯（PVC）及典型城市垃圾焚烧过程氯元素的化学平衡组成及其浓度，同时研究了脱氯剂对PVC及垃圾中氯转化的影响。计算结果表明，PVC热态反应的主要产物是HCl气体，在加入脱氯剂后温度低于600℃时，脱氯剂对HCl的脱除作用很明显；城市生活垃圾热解和燃烧过程中在温度超过600 ℃，垃圾中的有机氯和无机氯都将转化为HCl气体，而此时脱氯剂失去效果。由计算结果得到控制HCl生成，消除二口恶英污染物的生成反应工艺条件。     

Thermal decomposition study of sewage sludge and of organicwaste used in the sorption of metals

The conventional treatments of effluents containing heavy metals produce significant quantities of byproducts with recalcitrant characteristics, making necessary looking after alternative techniques in order to avoid the production of new contaminated residues. Sorption process of chromium and zinc in vertical columns loaded with sewage sludge and organic solid waste has been studied in this work. The data from the TG curves of the two sorbents presented significant differences when they were submitted to the metal uptake, being noticed the displacement of the thermal events towards lower temperatures for both types of sorbents studied. As it was expected, for both sorbents, an increase in the mass of samples has been observed at the completion of the thermal tests upon metal uptake. Therefore, these facts demonstrate that during the biosorption process a physico-chemical interaction took place between sorbents and metals, as it was evidenced by the more than 100 K increase in the decomposition temperatures as well as the variation of the ΔH values of the samples.     

Mineral–Carbon Sorbents Based on Aluminium Hydroxide and Atactic Poly(propylene)

The present work is an attempt to use the waste water stream, containing considerable amounts of aluminium chloride, for the manufacture of mineral–carbon sorbents. The use of the wastewater has given a possibility of obtaining a suitable mineral matrix of aluminium hydroxide for the sorbents. Atactic poly(propylene) (APP) have been used as the necessary carbon raw material. The modification of aluminium hydroxide was attained by preliminary mixing with the organic component, followed by carbonisation. Optimum conditions for obtaining Al(OH)₃ have been determined and the effect of the amount of carbon matter on the properties of the materials obtained has been evaluated. The studies have enabled to trace the changes in the structure and properties of the sorbents obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Adsorption and Structural Properties of Mineral–Carbon Sorbents

In the present work an attempt was made to obtain mineral–carbon sorbents by thermal decompositon. The mineral matrix for the sorbents (aluminium hydroxide) was based on petrochemical waste stream containing considerable amounts of aluminium chloride. Reference tests were carried out with a model solution prepared with the use of analytical grade AlCl₃. Atactic polypropylene and hydrocarbon mixtures obtained in the flotation of petrochemical waste waters were used as carbon-containing raw materials. The aim of this work was to determine the adsorption and structural characteristics of the complex sorbents and to check the possibility of evaluation of their hydrophobic-hydrophilic properties. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sorption extraction of lanthanides from phosphoric acid solutions

The possibility of sorption extraction of lanthanides from nitric-phosphoric and phosphoric acid solutions with inorganic sorbents based on hydrated titanyl hydrophosphate was studied. New technological solutions were suggested for lanthanide sorption from the products which are formed in processing of the Khibiny apatite concentrate on mineral fertilizers (frozen nitric-phosphoric acid extract, a product of nitric acid decomposition of apatite, and the production phosphoric acid from the dihydrate process).     

Use of acenaphthene as a carbon pyrolyzate carrier for the preparation of aluminium-carbon sorbents

The purpose of this study was a preliminary evaluation of mineral-carbon sorbents preparation possibility by the method of thermal decomposition of a mixture of aluminium oxide or hydroxide and acenaphthene and determination of their physicochemical properties. The conditions of carbonization were established and the changes of physicochemical properties of obtained materials as a function of organic substance content in the mineral-carbon mixture before the process of carbonization were tracked. In these investigations the methods of thermal analysis, low-temperature nitrogen adsorption and benzene vapors adsorption were applied.     

Hypercrosslinked strong anion‐exchange resin for extraction of acidic pharmaceuticals from environmental water

Two novel high‐specific surface area polymeric sorbents (HXLPP‐SAXa and HXLPP‐SAXb) were synthesised and evaluated as solid‐phase extraction sorbents. The novel sorbents under study are based on hypercrosslinked polymer microspheres and designed specifically to offer ion‐exchange properties; the specific polymers of interest in the current work have been chemically modified in such a way as to impart a tuneable level of strong anion‐exchange character onto the sorbents. The novel sorbents were applied as strong anion‐exchange sorbents in solid‐phase extraction studies, with the goal being to selectively extract a group of acidic compounds from complex environmental samples in an efficient manner. Out of two HXLPP‐SAX resins evaluated in this study, it was found that the sorbent with the lower ion‐exchange capacity (HXLPP‐SAXa) gave rise to the best overall performance characteristics and, indeed, was found to compare favourably to the solid‐phase extraction performance of commercial strong anion‐exchange sorbents. When the HXLPP‐SAXa sorbent was applied to the solid‐phase extraction of environmental water samples, the result showed quantitative and selective extraction of low levels of acidic pharmaceuticals from 500 mL of river water and 100 mL of effluent wastewater.     

Radiolytic degradation of pesticide 4-chloro-2-methylphenoxyacetic acid (MCPA)—Experimental data and kinetic modelling

The aqueous solutions of MCPA have been γ-irradiated in different conditions, where particular active radical species from water radiolysis predominate. The obtained data confirmed that largest yield of radiolytic decomposition is obtained in oxidation processes, where oxidation is carried out with hydroxyl radicals. The obtained data have been compared with kinetic modelling. A fair agreement was obtained for degradation of MCPA in different experimental conditions, including also irradiation in the presence of hydrogen peroxide, that in optimised conditions can be used to enhance the yield of decomposition. The obtained data have also shown a strong effect of the presence of large amount of chloride on yield of MCPA decomposition, which can be attributed to strong oxidation properties of chlorine radicals formed. It is also shown that MCPA can be completely decomposed in industrial wastes from various stages of MCPA production, although this is not accompanied by satisfactory reduction of toxicity of examined wastes.     

The application of solid sorbents for the purification of aluminum contaminated chemicals used as modifiers in electrothermal atomic absorption spectrometry

Various microcolumns with solid sorbents (ion exchange resins, functionalised cellulose sorbents, chelating resins) have been tested with respect to their ability for the purification of aluminum contaminated chemicals used as modifiers in electrothermal atomic absorption spectrometry. The purification of NaNO(3), Mg(NO(3))(2), K(2)SO(4) and (NH(4))(2)HPO(4) has been the most effective with an almost 100% efficiency, when Spheron-Oxine was used as chelating resin. The sorption of aluminum from KOH solution has been found to be very high (around 90%) for all investigated sorbents. However, the best results have been obtained with anion-exchange resins. It has been difficult to purify concentrated mineral acids (HCl, H(2)SO(4)). A retention of aluminum above 80% has been achieved only when Cellex P, Chelex 100 or Amberlite XAD-2 have been used.     

Characterization and pyrolysis behaviour of different paper mill waste materials

Paper industry generates a considerable amount of wastes. Their composition mainly depends on the type of paper produced and the origin of cellulose fibres. Nowadays, in Spain, 40% of solid wastes generated by the paper and pulp industry are deposited directly in landfill, 25% are used in the agriculture, 13% in the ceramic industry and 7% in the concrete production. In the last years, thermal treatment methods like combustion, pyrolysis and gasification have been widely study as alternative techniques for the valorization of different organic waste materials. The main objective of the present work is to study the pyrolysis behaviour of different paper mill waste materials. For this reason, a wide characterization of eight paper mill waste materials from different origins was performed using SEM, FTIR, DRX and thermogravimetric techniques. Paper mill sludges from recycled paper, mainly wastes obtained from deinking process, showed high CaCO₃ and clays contents. Compared with the elevated total organic matter content (TOM) of paper mill waste materials their low organic carbon content determined by Cr₂O₇²⁻ oxidation reveals the elevated chemical stability of organic matter, due to high content on cellulose fibres. Analysis of samples by SEM indicates that successive recycled processes of paper leads to paper mill waste materials with more degraded fibres. XRD analyses show as crystalline cellulose was present in reject and primary sludge from paper mills that produced paper from virgin wood. However, crystalline cellulose content significantly decreased in waste materials from recycled paper. Finally, thermogravimetric analysis indicates that presence or mineral matter and degradation of cellulose significantly influences their pyrolysis behaviour. In general, weight loss of paper mill waste materials started at lower temperatures than pure cellulose. In waste materials from recycled paper weight loss continues at temperatures highest than 500 °C due to kaolinite dehydration and carbonates decomposition.     

Effect of technique of applying layers of metal acetylacetonates on acid-base and chromatographic properties of sorbents

A series of chromatographic sorbents, which differ by way of applying modifying chelates of acetylacetone was obtained. The acid-base and chromatographic properties of sorbents with thermally and chemically grafted layers of metal acetylacetonates were investigated. It was shown that the modifi cation of the mineral sorbents with metal acetylacetonates leads to a change in the surface acidity, as well as to an increase in the polarity and selectivity with respect to different classes of compounds.     

Porous texture in hematite derived from goethite: Mechanism of thermal decomposition of geothite

The thermal decomposition of mineral goethite is investigated at various temperatures between 25 and 700°C in vacuo. The mineral used in the present work consists of the agglomerates in which primary particles of goethite are tightly bound to each other. At temperatures below 200°C, the water molecules that blocked the interstice within the primary particles are removed and, as a result, the slit-shaped voids of 3.7 nm in width are opened between the primary particles. The thermal decomposition of mineral goethite starts at the temperatures above 200°C. At 230–300°C, the silt-shaped micropores of uniform size (0.8 nm in width) are progressively opened in the course of decomposition reaction. The microporous texture obtained in the present work completely coincides with that obtained by decomposition of the synthetic goethite fine particles reported previously. The process of formation of the microporous texture has been examined in the light of the structural relationship of topotaxy between goethite and hematite. On the basis of the results of micropore formation, the process of nuclei formation of hematite in the goethite matrix is discussed.     

Adsorption properties of magnetic ferrospinel and sorbents on its basis

Adsorption of heavy metal ions (Cu²⁺ and Pb²⁺) on various samples of a manganese-zinc nano ferrospinel of composition Mn_0.7Zn_0.3Fe₂O₄, produced by the coprecipitation method, was studied. Samples of the starting ferrospinel and that modified with zinc and obtained in the presence of thermally treated agricultural wastes of cereal crops were examined. It was shown that all the three samples are effective sorbents. It was also found that the adsorption process on these sorbents is of complex type, depending on the nature of a metal ion being sorbed.     

Mechanism of thermal decomposition of zirconyl oxalate ZrOC<Subscript>2</Subscript>O<Subscript>4</Subscript>

Thermal decomposition of zirconyl oxalate hydrate was studied using DTA, TG, QMS and XRD techniques. It was shown that decomposition occurs in two stages: dehydration to anhydrous oxalate and next, decomposition to zircon oxide (zirconia). These steps are not well separated. We observed that significant amount of water are released during second stage of decomposition. Zircon dioxide is obtained in tetragonal form. Moreover, we consider some dependences between conditions of preparations zirconyl oxalate hydrate and some properties of solid product of its decomposition. Although the reaction of thermal decomposition of zirconyl salts is generally utilized in technology, many aspects of this process are still not sufficiently explained. In our work, we present some new interesting observations concerning thermal behaviour of zirconyl oxalate.     

Solid phase extraction of nitrate and nitrite anions using naturally and available sorbent

Radioactive waste contains nitrate and nitrite as well as radioactive fission products. Nitrate and nitrite anions are two of the major components of nuclear waste streams and contribute to environmental release hazards. The removal of nitrate and nitrite is a necessary step for the further treatment low-level radioactive wastes. The focus of the research is to evaluate the adsorption potential of solid phase derived from rice straw for nitrate and nitrite anions in single- and binary-component systems due to the fact that the rice straw is a very abundant and by-product material. The removal was accomplished under the optimize conditions of temperature, concentration, pH, contact time and quantity of adsorbent as these parameters are some of the main factors influencing the uptake of two solutes at the solid–solution interface. Batch-mode kinetic and equilibrium studies have been carried out. The experimental data was analyzed using equilibrium isotherm and kinetic models. The thermodynamic parameters (?G°, ?H°, and ?S°) were also determined using the equilibrium constant value obtained at different temperatures. Results show that this adsorbent is effective and much better or even superior than many sorbents for removal of nitrate and nitrite. The prepared sorbent as solid-phase extractant was successfully applied for the extraction of nitrate from actual water samples.     

Thermochemical investigations of natural phosphate with ammonium sulfate additive

Summary The free energy of the acidic ammonium sulfate is a good precondition its use as an additive or reagent for decomposition of natural phosphates on the way to obtain NPS or NPKS complex fertilizers. During our previous studies it was confirmed that as a result of thermo-mechanical treatment new solid phases are formed as a result of the phosphates decomposition. The aim of this study is to find out appropriate conditions for thermal treatment of Tunisia phosphorite with ammonium sulfate where the content of P₂O₅ soluble forms has its maximum. The process was investigated under dynamic thermal conditions. Structure and phase transformations of the mixtures to intermediate and final solid products are confirmed by different techniques. X-ray powder diffraction, infrared spectroscopy and electron microscopy have been applied successfully and relationship found between phase structure and thermal treatment applied. As a result of the complex studies optimal temperatures are determined. The solid products under optimal conditions contain phosphorous in soluble forms available for plants in the soil. As a final it is concluded that the final products could be used as complex mineral fertilizers.     

Thermal Analysis of new soil sorption regulators

After mechanochemical treatment of multicomponent mixtures complex fertilizers containing nitrogen, phosphorous, potassium and sulphur (NPKS) with higher water capacity were obtained. As raw materials some solid wastes and ammonia and potassium sulfates were used. Due to the different ratio used, new solid phases in the mixtures are formed. New solid phases are confirmed by the stages and rate of mass changes and also by the thermal effects at different temperature ranges. New phases are also confirmed by using X-ray diffraction method. On the base of data obtained mechanism of chemical transformations is proposed. It was found that the kinetics of mechanical activated mixtures decomposition is significantly influenced by the time of treatment and proceeds in few stages. The results have shown that the soluble nutrients forms ratio and sorption capacity could be controlled by the initial components ratios and treatment conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

New catalytic methods for processing solid organic raw materials

New catalytic methods are described for production of metallurgical coke and electrode materials from coals, carbon reductants, improved solid fuels and sorbents from lignite and lignine, levulinic acid from wood wastes, and aromatic aldehydes from lignin-containing stock.     

木质纤维类生活垃圾热解过程矿物质和碳结构的演化规律

使用水平管式炉,在不同热解温度(500~1 000 ℃)条件下对废纸屑和樟树叶两种木质纤维类生活垃圾进行了热解实验,分别采用X射线衍射(XRD)和拉曼光谱研究了样品所含矿物质和碳结构随热解温度的变化。结果表明,废纸屑和樟树叶含有的主要矿物分别为方解石和草酸钙,在500 ℃之前草酸钙全部转化为方解石,焦样中的方解石在800 ℃以后逐渐分解并形成生石灰。拉曼光谱对生活垃圾焦的碳结构变化非常敏感,低温热解时生活垃圾的大分子结构发生缩合和解聚,产生了孤立sp²碳原子,导致峰参数D1峰半高宽和峰面积比值I_D1/I_G逐渐增大;高温热解时晶体sp²碳原子增多,导致D1峰半高宽和I_D1/I_G逐渐减小。焦样的碳结构有序度随热解温度升高先降低后提高。