Volume 14 (2012): Issue 2 (June 2012)

Adsorption of methyl tert-butyl ether (MTBE) from aqueous solutions by granulated modified nanozeolites Y was investigated. Nanozeolite Y powders were converted into granulated zeolites and subsequently modified with two cationic surfactants (20 mmol/dm³), to be used as adsorbent. Granulated nanozeolites were characterized by BET surface area analysis, elemental analysis and X-ray diffractometer. -Hexade-cyltrimethylammonium (HDTMA-Cl) modified granulated zeolite had more effective performance than N-cetylpyridinium bromide (CPB) modified granulated zeolite. The most conventional adsorption isotherms and kinetic models were applied to describe MTBE adsorption and reaction dynamic, respectively. The equilibrium sorption data fitted the Langmuir 2 isotherm model and the kinetic study was followed the pseudo-second-order model. The maximum adsorption capacities for HDTMA-Cl modified zeolite and CPB modified granulated zeolite were 333.33 and 142.8 mg/g, respectively as calculated by the Langmuir model. This study demonstrated that the removal of mtbe by granulated modified nanozeolites Y is a promising technique.

A single-factor field experiment was carried out at the Cultivar Evaluation Station in Szczecin-Dąbie in 2008-2010. In the experiment, the compost produced with municipal sewage sludge by the GWDA method was used and high-calcium brown coal ash at a dose corresponding. A test plant was Virginia fanpetals (Sida hermaphodrita Rusby). The obtained results show that Virginia fanpetals biomass contained on average the most nitrogen (3.72 g·kg^-1 d.m.), calcium (6.03 g·kg^-1 d.m.) and sulphur (1.24 g·kg^-1 d.m.) in 2008, while the most potassium (4.39 g·kg^-1 d.m.) in 2010. Significantly more phosphorus, magnesium and sulphur was contained by Virginia fanpetals biomass from the objects where municipal sewage sludge compost had been applied without and with addition of high-calcium brown coal ash when compared to calcium carbonate or high-calcium brown coal ash being introduced into soil at the beginning of study. Differences in average nitrogen, potassium and calcium contents in the test plant biomass from particular fertilisation objects were not significant. The macroelements uptake by Virginia fanpetals biomass depended on the yield size and the content of chemical elements under discussion in it.

In the present study, ZnS nanoparticles were prepared using the mechanochemical method. The ZnS nanoparticles prepared were doped with different concentrations of manganese using metal acetate and manganese acetate by mechanochemical method. The as-prepared particles were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The photocatalytic activity of the prepared nanoparticles samples, in the photocatalytic degradation of malachite green, had been investigated. The nanoparticles were photo induced, generating hole transfer for photocatalytic activity. The photodegradation of malachite green was observed at different pH (2-5) values, dye concentrations (10-100mg/L) and amount of ZnS nanoparticles (1-2.5 g/L). About 95% degradation of dye was observed on the addition of 2 g/L ZnS in 50 mg/L dye solution after 90 minutes illumination at 125 W. Degradation has been increased up to 99% using UV/nanoparticles/H₂O₂ (50 mL/L) combined process. The degradation efficiency was also compared using Mn doped ZnS nanoparticles (Zn_1-x Mn_xS, where x = 0.01, 0.22 and 0.3). Maximum of 97% degradation was observed with 0.01% concentration of Mn. Kinetics study and performance of UV/ZnS, UV/ZnS/H₂O₂, UV/doped ZnS processes were evaluated to compare the efficiency of different processes.

In this research, the batch removal of Pb²⁺ ions from wastewater and aqueous solution with the use o two different modified algae Gracilaria corticata (red algae) and Sargassum glaucescens (brown algae) was examined. The experiment was performed in a batch system and the effect of the pH solution; initial concentration and contact time on biosorption by both biomasses were investigated and compared. When we used S. glaucescens as a biosorbent, the optima conditions of pH, Pb²⁺ concentration and equilibrium time were at 5, 200 mg/L and 70 min, in the range of 95.6% removal. When G. corticata was used for this process, pH 3, 15 mg/L pb²⁺ concentration and 50 min contact time, resulted in the maximum removal (86.4%). The equilibrium adsorption data are fitted to the Frundlich and Langmuir isotherm model, by S. glaucescens and G. corticata, respectively. The pb²⁺ uptake by both biosorbent was best described by the second-order rate model.

Gossypol is polyphenolic aldehyde, a toxic substance naturally present in cotton plant to protect it from insects, pests and diseases. Maximum gossypol is concentrated in the seed. After extraction of oil from the cottonseed, the defatted cottonseed meal which contains both the gossypol and proteinous matter is left behind. A number of attempts have been made using different solvents to extract gossypol from the seeds. However, all these efforts have remained in the realm of academic activity only as none of them could be commercialized. If a pilot plant or commercial scale plant is to be developed then the data on the kinetics and thermodynamics of the extraction process is required. In this study ethanol has been used as the solvent at temperature below 323K for removal of gossypol from the defatted seed. This study finds the effects of parameters viz. temperature, solvent to solid ratio (SR) and extraction time on the gossypol extraction efficiency. The data obtained are used to establish the kinetics and thermodynamics of the extraction process.

Performance of cation and anion exchangers was evaluated by carrying out breakthrough analyses of pH, conductivity, free mineral acid (FMA) and various dissolved solids for an industrial water treatment plant of 700 gpm capacity. The breakthrough curves showed no leakage of calcium, magnesium and chloride throughout the operating period of the train, however, they indicated the early leakage of sodium, potassium, sulphate and silica. The operating/breakthrough capacity, total capacity and degree of column utilization were determined. The column utilization was found to be 67.85%, 38.93% and 16.78% against the design values of 90%, 85% and 85% for cation, primary and secondary anion exchangers respectively. The operating time of the water treatment train was significantly increased by achieving adequate capacity utilization of secondary anion exchanger. The low capacity utilization of secondary anion resin due to early silica slippage, has been discussed in the paper.

Heterogeneous photocatalytic removal of Rhodamine-B (RhB) dye by metallic Au nanopatrticles deposited TiO₂ photocatalyst was studied. For this study, a chemical reduction method by hydrazine hydrate for gold deposition was employed in order to synthesize Au/TiO₂ nanocomposite system. For the characterization of the synthesized nanomaterials, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), the Fourier transformation infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PLS) techniques were performed. The obtained results show that the deposition of gold onto TiO₂ surface could effectively inhibit the recombination of the photoinduced electron and holes, improving the absorption capability for the visible light source and leading to the increased surface OH group density. The degradation experiment reveals that the efficiency of color removal from RhB aqueous solution containing Au/TiO₂ powders for the photocatalytic bleaching of RhB dye is more efficient than that of bare TiO₂ sample upon UV-vis light activation. In addition, degradation kinetics of RhB dye in aqueous suspensions can be well simulated by the Langmuir-Hinshelwood model and obeys the pseudo-first order law, with a decolorization rate of 0.0252 min^-1 to the photocatalytic removal of RhB dye.

A spent vanadium catalyst, from the plant of metallurgical type, was leached in a sulfuric acid solution to recover vanadium and potassium compounds. The effect of time, temperature, concentration of acid, catalyst particle size and phase ratio was studied. Additionally the concentration of iron, copper, zinc, arsenic and lead compounds was determined. The flow sheet for the proposed process of spent vanadium catalyst leaching is presented.

TiO₂ of anatase structure was modified by tungsten dioxide and H₂O₂ in order to obtain WO₃-TiO₂ photocatalyst with enhanced photocatalytic activity under both, UV and artificial solar light irradiations. WO₂ was dissolved in 30% H₂O₂ and mixed with TiO₂ in a vacuum evaporator at 70°C. Such modified TiO₂ was dried and then calcinated at 400 and 600°C.

The prepared samples and unmodified TiO₂ were used for the photocatalytic decomposition of humic acids (Leonardite standard IHSS) in the aqueous solution under irradiations of both, UV and artificial solar light. Modification of TiO₂ with tungsten dioxide and H₂O₂ improved separation of free carriers in TiO₂ which resulted in the increase of OH radicals formation. Calcination caused an increase of anatase crystals and higher yield in OH radicals. The uncalcined samples showed high abilities for the adsorption of HA. Combination of adsorption abilities and photocatalytic activity of photocatalyst caused that the uncalcined TiO₂ modified with WO₂/H₂O₂ showed the shortest time of HA mineralisation. The mineralisation of HA under the artificial solar light was much lower than under the UV. It was proved that, although OH radicals are powerful in the decomposition of HA, adsorption can facilitate the contact of the adsorbed molecules with the photocatalyst surface and accelerate their photocatalytic decomposition.

The composition of solvent-soluble organic matter of phosphorite, which is a precursor of volatile organic compounds emitted by the fertilizer industry, was studied. A benzene-methanol mixture and chloroform were used for the extraction of free and bound bitumen from phosphorites, respectively. The separated bitumen fractions were characterized qualitatively by GC-MS and quantitatively by GC-FID. n-Alkanes, n-alkenes, fatty acids and isoprenoids were identified in the extracts. The main components were n-alkanes and n-alkenes, constituting over 80% of the total bitumen determined. An unexpected presence of n-alkenes only in the free bitumen fraction was found. The possible source of ill-smelling substances evolved during treatment of phosphorite with H₂SO₄ was discussed.

Poly(aliphatic/aromatic-ester) (PED) multiblock copolymers belong to the class of thermoplastic elastomers (TPEs), characterized by a physical network of semi-crystalline hard segments. The PEDs were modified with e-beam to create an additional network structure. Polymers were evaluated using SEC, WAXS, DSC and quasi-static tensile tests. E-beam irradiation induced a significant increase of molecular weight and tensile strength of the PEDs. This effect, together with the diminished degree of crystallinity can be explained by the formation of chemical crosslinks, which are located in the hard phase segments.

Cross-linked humic acid supporting palladium (CL-HA-Pd) catalyst was prepared readily and characterized by infrared analysis (IR) and thermogravimetric analysis (TG). The catalyst could catalyze the Heck reaction of aryl halide or substituted aryl halide with vinyl compounds in N₂ atmosphere; the yields were above 95%. The catalyst could be recovered and reused 7 times with the Heck reaction of iodobenzene with acrylic acid, and the yield was above 75.6%. The results showed that the catalyst had high catalytic activity even at low temperature of 62°C or with a small amount of the catalyst.

The influence of the process temperature from 85°C to 95°C, the content of phosphates and sulphates in the wet process phosphoric acid (about 22-36 wt% P₂O₅ and about 2-9 wt% SO₄^2-) and the addition of αCaSO₄·0.5H₂O crystallization nuclei (from 10% to 50% in relation to CaSO₄·2H₂O) on the transformation of calcium sulphate dihydrate to hemihydrate has been determined. The wet process phosphoric acid and phosphogypsum from the industrial plant was utilized. They were produced by reacting sulphuric acid with phosphate rock (Tunisia) in the DH-process. The X-ray diffraction analysis was used to determine the phase composition and fractions of various forms of calcium sulphates in the samples and the degree of conversion of CaSO₄·2H₂O to αCaSO₄·0.5H₂O and CaSO₄. It was found that the transformation of CaSO₄·2H₂O to αCaSO₄·0.5H₂O should be carried out in the presence of αCaSO₄·0.5H₂O crystallization nuclei as an additive (in the amount of 20% in relation to CaSO₄·2H₂O), at temperatures 90±2°C, in the wet process phosphoric acid containing the sulphates and phosphates in the range of 4±1 wt% and 27±1 wt%, respectively.

A chelating resin based on Salicylic acid-Formaldehyde copolymer, containing Orcinol (SFO), has been synthesized and characterized on the basis of Elemental Analysis, Particle Size Distribution, FT-IR Analysis, XRD, SEM and Optical Photographs. The Physico-Chemical properties have been studied. This resin is highly stable in acidic and alkaline solutions and has been studied as a chelating sorbent for heavy metal ions and transition metal ions. The Exchange capacity order is Ni(II) > Cu(II) > Zn(II) > Cd(II) > Pb(II). The effect of nature and concentration of different electrolytes on distribution coefficient (K_d) for metal ions have been investigated. Separation of synthetic mixtures containing Cu(II)-Pb(II), Ni(II)-Cd(II) and Brass constituents has been carried out using a column prepared from the synthesized chelating resin. The developed procedure was also tested for the removal of Cd(II) and Pb(II) from natural water of Purna River near by Navsari, Gujarat, India.