Browsing by Author "Mordarski, Grzegorz"
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- Simultaneous removal of dyes and metal cations using an acid, acid-base and base modified vermiculite as a sustainable and recyclable adsorbentPublication . Stawiński, Wojciech; Węgrzyn, Agnieszka; Freitas, Olga; Chmielarz, Lucjan; Mordarski, Grzegorz; Figueiredo, SóniaThe aimof thiswork was the modification of vermiculite in order to produce a lowcost, efficient and sustainable adsorbent for dyes and metals. Three activation methods consisting of acid, base and combined acid/base treatment were applied to improve the of vermiculite's adsorption properties. Adsorbents were tested in single, biand tricomponent solutions containing cationic dyes and Cu2+ cations. The rawmaterial showed lowadsorption capacity for dyes and metal. The acid/base treated vermiculite had very good adsorption capacity toward dyes while the maximumadsorption capacity for Cu2+ did not change comparing to the startingmaterial. The alkaline treated vermiculite was a good adsorbent for metals,while still being able to remove dyes on the level of the not treated material. Moreover, it was shown that the materials may be regenerated and used in several adsorptiondesorption cycles. Furthermore, itwas possible to separate adsorbed dyes from metals thatwere desorbed, using as eluents ethanol/NaCl and 0.05MHNO3, respectively. This opens a possibility for sustainable disposal and neutralization of both of the pollutants or for their further applications in other processes.
- Study of adsorptive materials obtained by wet fine milling and acid activation of vermiculitePublication . Węgrzyn, Agnieszka; Stawiński, Wojciech; Freitas, Olga; Komędera, Kamila; Błachowski, Artur; Jęczmionek, Łukasz; Dańko, Tomasz; Mordarski, Grzegorz; Figueiredo, SóniaWet fine milling, as a pretreatment step to acid activation of vermiculite, was applied in order to decrease the environmental impact of the procedure commonly used to increase the mineral's adsorption capacity. Milling caused fragmentation of the material and several changes in its structure: edges of the flocks became frayed, the surface cracked, cation exchange capacity (CEC) increased, and most of the iron in oligonuclear and bulk form was removed. At the same time the specific surface area, crystallinity, chemical composition and adsorption capacity did not change significantly. Fine ground material was more susceptible to acid activation, which caused a decrease in the crystallinity and CEC, development of meso- and microporosity, an increase in the total volume of pores, in the specific surface and external surface areas. Micropores were developed faster in lower acid concentrations in the rough ground material, while the external surface area and total pores volume increased faster in the fine ground vermiculite. The latter material also had a higher CEC. Application of 0.5 mol L− 1 HNO3 to rough ground vermiculite did not change its adsorption capacity, however it changed from 55 ± 7 to 110 ± 8 mg g− 1 when the material was fine ground. The optimal treatment conditions for both materials were obtained for 1.0 mol L− 1 HNO3, however the adsorption capacity for the fine ground vermiculite increased more (i.e., from 55 ± 7 to 136 ± 7 mg g− 1) than for its rough ground counterpart (i.e., 52 ± 7 to 93 ± 7 mg g− 1). Concentrations higher than 1.0 mol L− 1 resulted in deterioration of the adsorption capacities in both cases. Considering all the experimental outcomes, it can be concluded that the environmental impact of acid activation of vermiculite may be diminished by application of fine grinding of the material before the chemical activation process. Such treatment resulted in higher adsorption capacity at a given acid concentration compared to the rough ground material.
- Sustainable adsorbents formed from by-product of acid activation of vermiculite and leached-vermiculite-LDH hybrids for removal of industrial dyes and metal cationsPublication . Stawiński, Wojciech; Węgrzyn, Agnieszka; Mordarski, Grzegorz; Skiba, Michał; Freitas, Olga; Figueiredo, SóniaHydrotalcite-like layered double hydroxide (LDH) materials were synthesized from liquid waste by-product produced during acid activation of vermiculite (raw (W) and expanded (Ve)), and by combining the waste with the activated mineral, novel hybrid vermiculite-hydrotalcite-like materials were obtained in one-pot synthesis. Batch system adsorption experiments were performed on fresh and calcined (at 450 °C) materials using two anionic dyes (Congo Red - CR, and Reactive Red 184 - R), a cationic dye (Astrazon Red - AR), and Cu2+. Calcination significantly increased the materials' adsorption capacities for all the pollutants. The highest adsorption capacities of the LDH derived from W were 289 ± 2, 137 ± 2, 38.2 ± 0.6 and 64 ± 2 mg g−1, while for the ones derived from Ve were 214 ± 2, 119.5 ± 0.3, 35.9 ± 0.7 and 66 ± 3 mg g−1 for CR, R, AR and Cu2+, respectively. The hybrids obtained from W attained removal levels of 238 ± 3, 111 ± 2, 44 ± 1 and 70 ± 1 mg g−1 and their counterparts derived from Ve reached 84 ± 1, 34.1 ± 0.5, 43 ± 2 and 75 ± 1 mg g−1 for CR, R, AR and Cu2+, respectively. Strong synergic effect on adsorption was observed in the hybrid materials, especially in these derived from Ve. These adsorbents had higher (up to 400%) adsorption capacities than theoretical ones prepared by mixing ex-situ appropriate amounts of activated vermiculite and LDH. All the materials were characterized by XRD, SEM-EDS, and ATR techniques. The proposed procedure is a sustainable approach to clay minerals valorization and my open new possibilities in fields such as wastewater treatment or catalysis.