Characterization of Particulate Matter from Direct Injected Gasoline Engines

The reactivity and reaction kinetics of particulate matter (PM) from direct injected gasoline (GDI) engines has been studied by O₂ and NO₂ based temperature programmed and isothermal step-response experiments, and the PM nano-structure has been characterized using HRTEM. The reactivity of the PM samples collected in filters during on-road driving was found to increase in the following order: Printex U < diesel < gasoline PI ≈ gasoline DI < ethanol for O₂ based combustion. The activation energies for O₂ and NO₂ based oxidation of PM collected from a GDI engine in an engine bench set-up was estimated to 146 and 71 kJ/mol respectively, which is comparable to corresponding values reported for diesel and model soot. Similar nano-structure features (crystallites plane dimensions, curvature and relative orientation) as observed for diesel soot were observed for gasoline PM.     

Singlet oxygen quenching activity of furan fatty acids: Kinetic and thermodynamics study

We have undertaken a detailed study of the reactivity of furan fatty acids (F-acids) with singlet oxygen (¹O₂) produced by thermal decomposition of endoperoxide and photosensitizer reaction of rose bengal in ethanol. Accordingly, we measured the second order rate constant (k_Q) for the reaction of F-acids with ¹O₂. As a result, the reactivity of F-acids against ¹O₂ exhibited a decrease in the order tetra-alkyl F-acid (F₃) > tri-alkyl F-acid (F₂) > di-alkyl F-acid (NMF). In addition, we also employed the density functional theory (DFT) and quantum chemical calculations to predict the chemical reactivity, stability, and thermodynamic properties of F-acids with respect to the quenching ¹O₂. In consequence, it is clear that log k_Q values of F-acids correlate with the energy level of the highest occupied molecular orbital (E_HOMO), and HOMO of F-acids may react with the lowest unoccupied molecular orbitals (LUMO) of ¹O₂. Moreover, the reaction of F-acids with ¹O₂ proceeds spontaneously in ethanol based on the calculation by thermodynamics method. These results suggest that the F-acids may contribute to the protection of oxidative damage in animals by quenching ¹O₂.     

Interaction of platinum colloids with single crystalline oxide and graphite substrates: a combined AFM,STM and XPS study

The reactivity of ternary V₂O₅-WO₃/TiO₂ De-NO _x catalysts is investigated by transient and steady-state techniques, and results have been compared with those obtained over binary V₂O₅/TIO₂ samples having the same V₂O₅ loading. The results indicate that the reactivity of the ternary catalysts in the SCR reaction is higher than that of the vanadia-titania samples, and that at low temperatures the SCR reaction occurs via a redox mechanism that involves at first the participation of the catalyst lattice oxygen and then the reoxidation of the reduced sites by gas-phase oxygen. Accordingly, the higher reactivity of the ternary catalysts has been related to their superior redox properties.     

Efficient oxidative desulfurization (ODS) of model fuel with H2O2 catalyzed by MoO3/γ-Al2O3 under mild and solvent free conditions

An efficient process to remove organic sulfur compounds from model fuel has been explored. Dibenzothiophene (DBT) and 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) can be completely oxidized into their corresponding sulfones by H₂O₂ over 14 wt.% MoO₃/γ-Al₂O₃ catalyst under mild conditions in 15 min. The effects of solvent, initial sulfide concentration, loading of MoO₃ and amount of catalyst on oxidative removal of DBT were studied. The employments of solvents have decreased the reaction rate of DBT, which can be attributed to the competitive adsorption between the sulfide and solvent. The oxidative reactivity increases in the order of thiophene (Th) < benzothiophene (BT) < DBT < 4, 6-DMDBT. The catalyst can be regenerated by methanol washing at 333 K.     

A kinetic study of lithium transport in the sol–gel Cr0.11V2O5.16 mixed oxide

The kinetics of the electrochemical lithium insertion reaction in the sol–gel chromium–vanadium mixed oxide Cr_0.11V₂O_5.16 has been investigated using ac impedance spectroscopy. The chemical lithium diffusion coefficient is found to be in the range 10⁻⁸/10⁻¹² cm²/s depending the Li content over the wide Li composition range 0 < x < 2 in Li_xCr_0.11V₂O_5.16. The evolution of the cathode impedance is investigated as a function of the lithium content and cycles. The results are discussed in relation with the cycling properties of the electrode material and the unusual structural response of the sol–gel mixed oxide which consists of a single phase behaviour with a continuous cell volume expansion of 6–7% in the 0 < x < 2 range for Li_xCr_0.11V₂O_5.16. For x < 1, a comparison with available kinetic data for the parent oxide indicates a very close behaviour. Cr_0.11V₂O_5.16 is shown to be the best V₂O₅-based cathode material with an initial specific capacity of 280 mAh/g at C/10 rate and still 240 mAh/g after 50 cycles in the 3.8–2 V potential range. The present kinetic data seem to indicate its better cycling behaviour mainly originates from its specific structural response rather than from kinetic reasons.     

Peroxidase-catalyzed polymerization ofp-cresol in supercritical CO2

The feasibility of the catalysis of horseradish peroxidase (HRP) in supercriticalCO ₂ was studied for the polymerization ofp-cresol in the presence of H₂O₂. The reactions were performed at 40‡C and 74.8 aim (1 100 psia) above the critical conditions ofCO ₂. In the initial tests with 2 mM ofP-crcsol and 1 mM of H₂O₂, more oligomers ofp-cresol were produced as more HRP was added. This indicates that HRP is active in supercritical CO₂. HRP was not completely inhibited by H₂O₂ at concentrations up to 20 mM. Increasing the initial concentrations ofp-cresol and H₂O₂ to 20 mM, respectively, resulted in the formation of precipitates which were undissolved either in water or in dimcthylforamide (DMF). The effects of adding water and/or methanol as cosolvents on the reactivity of HRP were studied subsequently. When more than 13.3 mL of water per liter of reaction volume was added, the formation of precipitates was not observed. The reactivity of HRP was sustained when up to 11.8 mL of methanol per liter of reaction volume was added. In most cases conversion ofP-cresol was less than 50% for 5 hours of reaction time.     

Mechanism on reduction and nitridation of micrometer-sized titania with ammonia gas

Ammonia gas can be simultaneously used as a reductant and nitrogen source to prepare TiN from titania. In this work, the mechanisms on reduction and nitridation of micrometer-sized anatase with ammonia gas have been investigated, using both thermodynamic and experimental studies. The thermodynamic analysis indicated that reduction and nitridation of TiO₂ by NH₃ was feasible. Anatase will undergo different paths to form TiN, depending on the reaction temperature. Upon heating, NH₃ was seen to partially decompose into N₂ and H₂, although the actual NH₃ decomposition ratio was less than the theoretical value. The experimental results indicated that the obtained titanium nitride was non-stoichiometric (TiN_xO_1−x, x ≤ 1), as it contained a certain amount of oxygen. Based on the phase transformation and X-ray photoelectron spectroscopy analysis, the reduction and nitridation routes were deduced: TiO₂ reacted with NH₃ to form TiN_xO_1−x directly, at lower temperatures, and followed the path TiO₂ → Ti_nO_2n−1 → TiN_xO_1−x, at higher temperatures. Ti_nO_2n−1 was determined to be Ti₄O₇ and Ti₃O₅ at 1100°C and 1200°C, respectively. Reaction temperature and time significantly affected the oxygen and nitrogen contents in TiN_xO_1−x, with the lattice parameter of roasted products gradually increasing—approaching those of pure TiN—with an increase in reaction temperature and holding time. At the same time, the content of oxygen in TiN_xO_1−x decreased, and its nitrogen content correspondingly increased.     

Enhanced dielectric and microwave absorption properties of LiCoO2 powders by magnesium doping in the X-band

The solid-state reaction was adopted to prepare a series of LiCo_1−xMg_xO₂ powders doped with different amount of Mg²⁺. The XRD patterns reveal single phase for all the prepared materials. The shift of the electronic structure of LiCo_1−xMg_xO₂ has been investigated by X-ray photoelectron spectroscopy to confirm the single phase for material. Influence of dopant amount on the electromagnetic properties of LiCoO₂ powders was analyzed. The dielectric and the microwave absorption properties were evaluated. Results showed that with the increase in Mg the complex permittivity decreased after increasing. Maximum values of both real part (ε′ = 16.2 at 8.2 GHz) and imaginary part (ε″ = 4.1 at 8.2 GHz) were obtained for x = 0.06. Monolayer absorbent containing 75 wt% LiCo_0.94Mg_0.06O₂ had the peak microwave absorption properties in a thickness of 2.1 mm. The available bandwidth (<−10 dB) was obtained in 8.4-10.2 GHz and the minimum reflection loss was −50.4 dB, which indicated that LiCo_1−xMg_xO₂ powders would be potential materials as microwave absorption.     

Hydrodesulfurization of dibenzothiophene over supported and unsupported molybdenum carbide catalysts

A series of γ-Al₂O₃ supported molybdenum carbides [carbided Mo/γ-Al₂O₃ (MCS), Co-Mo/γ-Al₂O₃ (CMCS), and Ni-Mo/γ-Al₂O₃ (NMCS)] and unsupported molybdenum carbide (MCUS) were prepared by the temperature-programmed carburization of their corresponding molybdenum nitrides with 20 % CH₄/H₂. XRD and SEM studies show that unsupported molybdenum carbide catalyst possesses a typical crystalline Mo₂C (FCC structure), while supported molybdenum carbide catalysts possess highly dispersed surface molybdenum carbide species on an alumina oxide support. The results of dibenzothiophene (DBT) hydrodesulfurization over molybdenum carbide catalysts show that the reactivity is strongly dependent on the type of catalyst. Supported molybdenum carbide catalysts possess a higher reactivity than the unsupported molybdenum carbide catalyst. In addition, Co or Ni promoted, supported molybdenum carbide catalyst possesses a higher reactivity than the unpromoted, supported molybdenum carbide catalyst. The reactivity, which is also dependent on the reaction conditions, increases with increasing reaction temperature and pressure and contact time. The CO uptakes of the molybdenum carbide catalysts correlate well with overall activity (total rate) for DBT hydrodesulfurization. The major reaction product is biphenyl, with cyclohexylbenzene next in abundance regardless of the type of catalysts and reaction conditions. It was also found that the molybdenum carbide catalysts exhibit stable initial reactivity due to the stable and weak acidic characteristics of these catalysts.     

Water as a Promoter of the Complete Oxidation of Volatile Organic Compounds over Uranium Oxide Catalysts

The effect of water addition on the complete oxidation of benzene and propane VOCs by uranium oxide catalysts has been investigated. Benzene oxidation was studied using a silica supported U₃O₈ catalyst. Complete oxidation is promoted by the addition of 2.6% water compared with the reactivity when no water is added to the reactant feed. Increasing the water concentration to 12.1% resulted in a suppression of oxidation activity. Investigation of propane oxidation using U₃O₈ shows a dramatic promotion of activity. Propane conversion was ca. 50% at 600 °C without added water, whilst it increased to 100% at 400 °C with the addition of 2.6% water. A comparison of oxidation activity has been made with Mn₂O₃, an oxide recognised for complete oxidation. In contrast to the U₃O₈ catalysts the addition of 2.6% water suppresses the activity of Mn₂O₃. In situ powder X-ray diffraction studies showed that the bulk U₃O₈ structure was stable under all the reaction conditions. The origin of the increased activity is not clear but may be due to modification of the catalyst surface and the contribution from new reaction pathways such as steam reforming.     

Catalytic effects of potassium on lignin steam gasification with <Emphasis Type="Italic">γ</Emphasis>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> as a bed material

The effects of potassium on the reactivity of biomass-char steam gasification with the presence of a porous material were investigated by using a thermogravimetric reactor with high-heating rates. Lignin was employed as a char-rich biomass model compound. The potassium carbonate (K₂CO₃) was added to lignin and a mixture of lignin and γ-Al₂O₃ porous particles by means of aqueous impregnation. The effects of K₂CO₃ and γ-Al₂O₃ addition on pyrolysis of lignin and steam gasification of lignin-derived char were evaluated in terms of lignin conversion and the gaseous products. Results showed that K₂CO₃ slightly increased the steam gasification rate of lignin-derived char, but it did not influence the conversion in both the pyrolysis and steam gasification steps. In addition, tar was reduced by adding K₂CO₃ because of the increment of carbon conversion to gas product. The presence of γ-Al₂O₃ was found to induce the lower reactivity of resulting char after pyrolysis, reducing the gasification rate and conversion. A significant improvement in gasification conversion was observed with the presence of both K₂CO₃ and γ-Al₂O₃. Especially, almost complete gasification was achieved at a reaction temperature of 1,073 K.     

Comprehensive kinetic characterization of the oxidation and gasification of model and real diesel soot by nitrogen oxides and oxygen under engine exhaust conditions: Measurement, Langmuir-Hinshelwood, and Arrhenius parameters

The reaction kinetics of the oxidation and gasification of four types of model and real diesel soot (light and heavy duty vehicle engine soot, graphite spark discharge soot, hexabenzocoronene) by nitrogen oxides and oxygen have been characterized for a wide range of conditions relevant for modern diesel engine exhaust and continuously regenerating particle trapping or filter systems (0-20% O₂, 0-800 ppm NO₂, 0-250 ppm NO, 0-8% H₂O, 303-773 K, space velocities 1.3 × 10⁴-5 × 10⁵ h⁻¹). Soot oxidation and NO₂ adsorption experiments have been performed in a model catalytic system with temperature controlled flat bed reactors, novel aerosol particle deposition structures, and sensitive multicomponent gas analysis by FTIR spectroscopy. The experimental results have been analyzed and parameterized by means of a simple carbon mass-based pseudo-first-order rate equation, a shrinking core model, oxidant-specific rate coefficients, Langmuir-Hinshelwood formalisms (maximum rate coefficients and effective adsorption equilibrium constants), and Arrhenius equations (effective activation energies and pre-exponential factors), which allow to describe the rate of reaction as a function of carbon mass conversion, oxidant concentrations, and temperature. At temperatures up to 723 K the reaction was driven primarily by NO₂ and enhanced by O₂ and H₂O. Within the technically relevant concentration range the reaction rates were nearly independent of O₂ and H₂O variations, while the NO₂ concentration dependence followed a Langmuir-Hinshelwood mechanism (saturation above ∼200 ppm). Reaction stoichiometry (NO₂ consumption, CO and CO₂ formation) and rate coefficients indicate that the reactions of NO₂ and O₂ with soot proceed in parallel and are additive without significant non-linear interferences. The reactivity of the investigated diesel soot and model substances was positively correlated with their oxygen mass fraction and negatively correlated with their carbon mass fraction.     

Etude de la reaction du carbone avec le sulfure d'hydrogene H2S a hautes temperatures et sous basses pressions

Reaction of carbon with hydrogen sulfide at high temperature (1000–2000°C) and low pressure (10^?4–10^?2 Torr) exhibits the following features:—carbon disulfide CS₂ is the only carbonaceous reaction product. There is no indication that CS₂ would originate from a secondary reaction of the unstable carbon monosulfide CS. Some decomposition of H₂S into its elements is also observed (Figs. 1–3).—as already observed in other high temperature carbon gasification reactions, the intrinsic reactivity of the sample surface is temperature and pressure dependent. Consequently, transitory or stationary rates are observed, depending respectively upon a changing or a stationary surface state of the carbon sample (Fig. 4). The changes in the surface state are more marked for amorphous than for graphitized samples (Fig. 5).—below 1700°C, the true reaction order is smaller than one, as a consequence of the high stability of the carbon-sulfur surface complexes.—for ungraphitized samples, the carbon surface loses slowly and irreversibly its ability to change with changes in pressure and temperature.All these features were previously observed in the reaction of carbon with sulfur vapor: consequently hydrogen sulfide appears to behave simply as a gaseous sulfur carrier. The kinetic behaviour is in agreement with former interpretations assuming presence of peculiar reactive sites, which originate from chemical attack of the solid but disappear due to a surface thermal heating process.Confirming also previous assumptions, sulfur chemisorption strongly affects the reaction kinetics, as shown by the influence of H₂S traces on the kinetics of the C-O₂ reaction (Fig. 10):—at lower temperatures (< 1300°C) there is an important inhibiting effect on the CO production: H₂S is adsorbed strongly on the reactive sites which become inaccessible to O₂ molecules.—in the intermediate temperature range an enhancing effect is observed which is attributed to a hindrance of thermal healing (caused by chemisorption still present).Finally, the kinetic features as a whole are tentatively summarized in a comprehensive diagram where the consistency of experimental results appears clearly.     

Comments on the mechanism of the vapour‐phase catalytic synthesis of thiophenes

A study of the synthesis of thiophene from the reaction of butanol and CS₂ over potassium‐promoted Cr₂O₃/γ‐Al₂O₃ has been performed by examination of the reactivity of model intermediates. This study indicates that the reaction path involves successive dehydrogenation, O/S exchange and dehydroheterocyclization. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of A-site ion nonstoichiometry on the chemical stability and electric conductivity of strontium and magnesium-doped lanthanum gallate

A series of Sr-ion deficient perovskites La_0.8Sr_0.2−xGa_0.8Mg_0.2O_2.8−δ (LSGM8282, x = 0.00, 0.05, 0.10, 0.15, 0.20), was synthesized by a conventional solid-state reaction method and their electric conductivity and chemical reactivity with Gd-doped ceria were investigated. Reactivity tests between the LSGMs and Ce_0.9Gd_0.1O_2−δ (GDC) were carried out by X-ray diffraction, SEM-EDS, and electric conductivity measurements. The Sr-ion deficient LSGMs have a lower reactivity against the formation of high-resistivity phases than the stoichiometric (x = 0.00) LSGM. The reaction layer formed at the interface of LSGM and GDC during the sintering process due to the mutual diffusion of the cations was classified into five layers depending on the composition. The introduction of the Sr-ion deficient LSGM suppressed the formation of the highly resistive Sr-rich (La_1+xSr_1−x)Ga₃O_7−δ phase. It was suggested that the Sr-ion deficient LSGM (La_0.8Sr_0.2−xGa_0.8Mg_0.2O_2.8−δ) of x = 0.15 was the best composition for suppressing the reaction with the GDC interlayer while retaining a relatively good electric conductivity.     

From single crystals to supported nanoparticles in experimental and theoretical studies of H2 oxidation over platinum metals (Pt, Pd): Intermediates, surface waves and spillover

The present paper reviews our investigations concerning the mechanism of H₂ + O₂ reaction on the metal surfaces (Pt, Pd) at different structures: single crystals (Pt(1 1 1), Pt(1 0 0), Pd(1 1 0)); microcrystals (Pt tips); and nanoparticles (Pd–Ti³⁺/TiO₂). Field electron microscopy (FEM), field ion microscopy (FIM), high-resolution electron energy loss spectroscopy (HREELS), XPS, UPS, work function (WF), TDS and temperature-programmed reaction (TPR) methods have been applied to study the kinetics of H₂ oxidation on a nanolevel. The adsorption of both O₂ and H₂ and several dissociative products (H_ads, O_ads, OH_ads) was studied by HREELS. Using the DFT technique the equilibrium states and stretching vibrations of H, O, OH, H₂O, adsorbed on the Pt(1 1 1) surface, have been calculated depending on the surrounding of the metal atoms. Sharp tips of Pt, several hundreds angstroms in radius, were used to perform in situ investigations of the dynamic surface processes. The FEM and FIM studies on the Pt-tip surface demonstrate that the self-oscillations and waves propagations are connected with periodic changes in the surface structure of nanoplane (1 0 0)-(hex) ↔ (1 × 1), varying the catalytic property of metal. The role of defects (Ti³⁺-□_O) in the adsorption centers formation, their stabilization by the palladium nanoparticles, and then the defects participation in H₂ + O₂ steady-state reaction over Pd–Ti³⁺/TiO₂ surface have been studied by XPS, UPS and photodesorption techniques (PhDS). This reaction seems to involve the “protonate” hydrogen atoms (H⁺/TiO_x) as a result of spillover effect: diffusion of H_ads atoms from Pd particles on a TiO_x surface. The comprehensive study of H₂, O₂ adsorption and H₂ + O₂ reaction in a row: single crystals → tips → nanoparticles has shown the same nature of active centers over these metal surfaces.     

Voltametric behaviour of Ti n O2n−1 ceramic electrodes close to the hydrogen evolution reaction

Voltammetric behaviour close to the hydrogen evolution reaction has been studied on metallic conducting oxides from Ti _n O_2n–1 series with n = 4–6. The Ti₄O₇, Ti₅O₉ and Ti₆O₁₁ ceramic electrodes were prepared by the reduction of TiO₂ compacts with hydrogen. The current-voltage curves (i, E) were obtained by the potentiodynamic method in aqueous solutions. The electrochemical reaction which occurs in the cathodic potential region is discussed in terms of proton insertion into the Ti _n O_2n–1 structure. The influence of the porosity of the ceramic electrodes on the electrochemical reaction taking place in this potential region was examined using electrodes of different pore size distributions (different values of roughness factor, r). The influence of the degree of reduction of titanium oxide (n in Ti _n O_2n–1) on the electrolytic activity for the hydrogen evolution reaction on these oxides was examined.     

Thermochemical investigation of lithium borate glasses and crystals

Lithium borate (LB) glasses and crystals with x = Li/(Li + B) = mole fraction of Li₂O of 0.2–0.5 have been synthesized by the quenching method. The thermodynamics of these materials were analyzed by high-temperature oxide melt solution calorimetry. The formation enthalpies from oxides of glasses range from −33.6 to −67.3 kJ/mol and those of crystals range from −42.1 to −77.4 kJ/mol, where compositions are given on the basis of one mole of (Li₂O + B₂O₃). The formation enthalpies of both glasses and crystals become more negative with increasing Li₂O mole fraction up to 0.5. The enthalpies of formation of glasses can be fit over the entire composition range (0 < x < 1) by a quadratic polynomial). The vitrification enthalpies were derived for x = 0.2 to 0.5 and ranged from 8.5 to 17.6 kJ/mol. The main factors controlling energetics are the strongly exothermic acid–base reaction between the network former (B₂O₃) and the network modifier (Li₂O) and the formation of tetrahedrally coordinated boron in the glasses and crystals.     

Catalytic Activity of Supported Platinum and Metal Oxide Catalysts for Toluene Oxidation

Oxidation of toluene has been investigated over supported platinum as well as over a variety metal oxide (M _x O _y ) catalysts dispersed on high surface area γ-Al₂O₃. Catalysts were characterized with respect to their specific surface area (BET), metal dispersion (selective chemisorption of CO), phase composition and M _x O _y crystallite size (XRD) and reducibility (H₂-TPR). Catalytic performance for the title reaction was investigated in the temperature range of 100–500 °C, using a feed composition consisting of 0.1% toluene in air. For Pt/M _x O _y catalysts, it has been found that catalytic performance depends on the nature of the support, with Pt/CeO₂ being the most active catalyst at low temperatures. The intrinsic reaction rate per surface platinum atom does not depend on Pt loading (0.5–5 wt%), at least for Pt/Al₂O₃. Reducible metal oxides, such as ceria, are active for the title reaction and catalytic performance is improved significantly with increase of specific surface area (SSA). However, the intrinsic reaction rate per unit surface area is invariant with SSA. Dispersion of M _x O _y on high surface area inert supports, such as Al₂O₃, results in materials with relatively high catalytic activity, which seems to correlate well with the reducibility of metal oxides. Catalytic performance of M _x O _y /Al₂O₃ catalysts can be optimized by proper selection of M _x O _y loading. Best performing catalysts of this series include 60% MnO, 90% CeO₂ and 5% CuO on Al₂O₃ which, under the present experimental conditions, are able to completely convert toluene toward CO₂ at temperatures lower than 350 °C. Dispersion of Pt on M _x O _y /Al₂O₃ catalysts improves significantly the catalytic performance of irreducible M _x O _y but does not alter appreciably the activity of reducible M _x O _y /Al₂O₃ catalysts.     

Preparation and evaluation of the chitin derivatives for wastewater treatments

The chitin thiocarbonate—Fe(II)H—H₂O₂ redox system was investigated as the initiator for the graft copolymerization of acrylonitrile and acrylic acid monomers onto chitin powder. The reaction with vinyl monomers onto chitin was carried out under various parameters of the graft copolymerization reaction to elucidate the polymerization behavior in terms of graft yield. Reactions of chitin—acrylonitrile graft copolymer with hydroxyl amine hydrochloride, as well as, sodium hydroxide were conducted in order to obtain chitin—(amidoxime-co-acrylonitrile) and chitin-(acrylate-co-acrylamide) graft copolymers, respectively. The reaction efficiency depends upon the alkali concentration, time, temperature, and on the reactant concentrations. The prepared chitin derivatives were evaluated for use in the wastewater treatments for adsorption and desorption of heavy metal ions as well as acid and basic dyes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1939–1946, 1997