Antoni W. Morawski

Application of TiO2-mounted activated carbon to the removal of phenol from water

Abstract TiO 2 -mounted activated carbon was prepared through hydrolytic precipitation of TiO 2 from teraisopropyl orthotitanate and following heat treatment at 650–900xa0°C for 1xa0h under a flow of nitrogen. The removal of phenol from its aqueous solution under UV irradiation was measured on TiO 2 -mounted activated carbons thus prepared. Although BET surface area of TiO 2 -mounted activated carbons decreased drastically in comparison with the original activated carbon, the efficiency of phenol removal under UV irradiation was high. The sample heated at 900xa0°C, which consisted mainly of rutile phase, showed the highest total removal of phenol. Efficiency of phenol degradation is reduced because of phenol adsorption on the catalyst.

Photocatalytic decomposition of azo-dye acid black 1 in water over modified titanium dioxide

Abstract The photocatalytic oxidation of an azo-dye acid black 1 (AB1) in water has been investigated over modified titanium dioxide (Tytanpol A11, “Police” Chemical Factory, Poland). The effect of operational parameters, i.e. pH of the solution, photocatalyst content, initial dye concentration on the photocatalytic process has been examined. It can be stated that the complete removal of color, after selection of optimal operational parameters, using modified Tytanpol A11 can be achieved in relatively short time, about 1xa0h. The catalytic material has been characterized by several analytical methods, like XRD, FTIR, UV–VIS/DRS.

Membrane distillation of NaCl solution containing natural organic matter

Abstract The concentration of NaCl solution containing natural organic matter by membrane distillation (MD) has been performed. The salt solution produced during animal intestines processing was used as a feed. The presence of organic compounds in the feed caused the fouling of MD membranes. The experiments were performed with polypropylene capillary membranes. A rapid flux decline caused by the deposition of organic matter on the membrane surface has been observed. The morphology and composition of the fouling layer was studied using scanning electron microscopy (SEM) coupled with energy dispersion spectrometry (EDS) and Fourier transform infrared with diffuse reflectance spectroscopy (FTIR-DRS). Protein and sodium chloride constituted the major components of the gel layer. Rinsing of the MD module with a 2xa0wt.% citric acid solution removed a part of the fouling layer. Boiling of spent NaCl solution followed by filtration resulted in the separation of the organic matter in the form of a deposit. This enabled a significant reduction in the occurrence of fouling phenomenon.

Study on the concentration of acids by membrane distillation

Abstract The membrane distillation (MD) process was applied for the concentration of different mineral acids, such as, sulfuric phosphoric, hydrochloric and nitric acids. The MD of a citric acid solution as an example of an organic acid was also investigated. The experiments were carried out keeping the warm feed and cold solution temperatures at 333 and 293 K, respectively. The data obtained indicate that the volume flux of a permeate decreased with an increase of acid concentration in the feed. The reduction of acid content in the permeate, close to 100%, for non-volatile acids was independent of the acid concentration in the feed. The amounts of hydrochloric or nitric acids in the permeate increased with a rise of the acid concentration in the feed, reaching the azeotropic composition. The effect of the polarisation phenomena on the concentration process of sulfuric acid is discussed.

Purification of oily wastewater by hybrid UF/MD.

Investigations on the treatment of oily wastewater by a combination of ultrafiltration (UF) and membrane distillation (MD) as a final purification method have been performed. A tubular UF module equipped with polyvinylidene fluoride (PVDF) membranes and a capillary MD module with polypropylene membranes were tested using a typical bilge water collected from a harbour without pretreatment. The permeate obtained from the UF process generally contains less than 5 ppm of oil. A further purification of the UF permeate by membrane distillation results in a complete removal of oil from wastewater and a very high reduction of the total organic carbon (99.5%) and total dissolved solids (99.9%).

A new route for preparation of TiO2-mounted activated carbon

Abstract TiO 2 -mounted activated carbon was prepared by the precipitation of TiO 2 from tetraisopropyl orthotitanate on the surface of poly(vinyl butyral) (PVB) and subsequent carbonization to different final temperatures from 700 to 900xa0°C under a flow of carbon dioxide. Photoactivity of the prepared TiO 2 /carbon composities was checked by decomposition of phenol in aqueous solution under UV irradiation. Adsorption of phenol on these catalysts was found to be very small (0–4%) without UV irradiation. Almost complete removal of phenol after 12xa0h under UV irradiation was observed for the sample heated to 700xa0°C that consisted of a single phase of anatase with 2.5% carbon. Carbon suppressed transformation of anatase onto rutile during heat treatment process. It has some benefits such as improving the crystalline structure of TiO 2 catalyst by using higher temperature of heat treatment and selection of the proper carbon precursor for carbonisation. Prepared TiO 2 mounted on carbon could be easily separated from the solution and it can be used repeatedly for phenol removal with preservation of its photoactivity.

Removal of organic matter by coagulation enhanced with adsorption on PAC

Abstract The removal of humic acids and phenol from model solution by coagulation and adsorption on powdered activated carbon (PAC) was investigated. A PAX XL-69 polyaluminum chloride was applied as a coagulant. The adsorption of humic acids and phenol on activated carbon for single- and bi- component solutions was studied. It was found that coagulation without PAC addition was less effective than the adsorption-coagulation integrated system. Coagulation enhanced with adsorption on activated carbon was more effective when coagulation was preceded by adsorption than when the two processes were carried out simultaneously. The best results were obtained at pH 7. Phenol and color were removed pletely, UV 254 absorbance was reduced by about 99% and COD-Mn was reduced by 81–89%.

Membrane distillation with laminar flow

Direct-contact membrane distillation (MD) process in a plate-and-frame module with laminar flow is investigated. The performance of a MD process is strongly influenced by heat transfer taking place within the membrane modules. The present study is concerned mainly with heat transfer across membranes, and specifically with assessing the applicability of existing heat-transfer coefficient correlations to MD membrane modules.

Photocatalytic degradation of Reactive Black 5: A comparison between TiO2-Tytanpol A11 and TiO2-Degussa P25 photocatalysts

The present studies provide the results from a comparison of two photocatalysts in form of titanium dioxide: TiO2-Tytanpol A11 commercially produced on Polish market by Police Company and the most popular titanium dioxide used in investigations — P25 produced by Degussa Company. Photocatalytic oxidation of azo-dye Reactive Black 5 (RB5) was chosen as the test reaction. The titania materials have been characterised by several analytical methods, like XRD, FT-IR/DRS and DR UV–VIS. The effect of operational parameters such as quantity of photocatalyst and pH of reaction medium on the photocatalytic degradation of RB5 in water has been investigated. The degrees of RB5 decomposition were lower by about 30% for A11 than for P25 in all cases. It can be stated that this lower activity of A11 results from different physical properties of two titania materials.

Photocatalytic decomposition of oil in water

Abstract Various titanates prepared by calcination of a mixture of KOH [Ba(OH)2 or Ca(OH)2] and titanium dioxide slurry with a slightly crystallized structure were used as photocatalyst in the reaction of oil decomposition in water. The influence of both the calcination temperature and the kind of metal used on the photocatalytic activity of resulted titanates in the oil decomposition reaction in water have been studied. The phase composition of photocatalysts was determined by XRD technique. The correlation between the photocatalyst content, time of UV-illumination and the rate of oil decomposition were presented. The most active material was prepared from a slightly crystallized titania precursor and potassium hydroxide calcinated at 550°C. The complete oil decomposition was achieved after 2xa0h of UV illumination with the photocatalyst content of 0.5xa0gxa0dm−3. The photocatalyst forms a complex mixture of various titanium oxides and titanates that are probably responsible for the increase of activity. For the most active TiO2/KOH photocatalyst the optimal preparation conditions were established.