Sorpcja fenolu z roztworów wodnych na konwencjonalnych i niekonwencjonalnych sorbentach

Badania własne przedstawione w niniejszej pracy dotyczą procesu sorpcji fenolu z wody na wysuszonych osadach ściekowych i na stałych produktach ubocznych powstających podczas procesu ich zgazowania (popiół). Zgazowanie jest obiecującą metodą termicznego zagospodarowania palnych substancji organicznych, niemniej jednak wciąż nierozwiązanym problemem jest sposób zagospodarowania powstających stałych produktów odpadowych. W ramach badań statyki procesu określono zarówno zdolność sorpcyjną, jak i czas osiągnięcia stanu równowagi fenolu na badanych materiałach sorpcyjnych. Badano także wpływ początkowego stężenia fenolu na jego pojemność sorpcyjną. Do matematycznego opisu sorpcji wykorzystano równania Langmuira oraz Freundlicha. Zakres pracy obejmował również ocenę zjawiska uwalniania z materiałów adsorpcyjnych pierwotnych substancji nieorganicznych i organicznych wraz z wyznaczeniem efektu toksycznego roztworu, stosując metody pośrednie. W podsumowaniu pracy, bazując na rezultatach wyników badań eksperymentalnych oraz różnych źródłach literaturowych, porównano pojemność sorpcyjną fenolu na konwencjonalnych i niekonwencjonalnych sorbentach.

The use of adsorption methods in wastewater treatment allows achieving high quality levels of the streams discharged into the environment. This is particularly taking into account the presence of different toxic and hazardous organic and inorganic substances in the wastewater. This problem applies to both municipal wastewater after mechanical-biological treatment as well as to industrial wastewater. Active carbon is the most commonly used for this purpose. However, novel opportunities are sought, including, for example, the use of waste (with appropriate physicochemical characteristics) as sorbents. The studies presented in this paper are related to the process of sorption of phenol from water on the dried sewage sludge and solid by-products generated during the gasification process (ash). Gasification is a promising method of thermal management of combustible organic substances. Nevertheless, there is still an unresolved problem connected with management of solid waste by-products generated during the process. In the frame of the study of the process statics susceptibility to sorption and the time to reach steady state of the phenol on sorption materials studied were determined. The effect of the initial concentration of the phenol on his sorption was also examined. For the mathematical description of adsorption Langmuir and Freundlich equations were used. The scope of the work also included an assessment of the phenomenon of release from adsorbent materials the primary inorganic and organic substances. Simultaneously, a solution toxic effect based on the indirect methods was determined. Additionally, based on the literature results, efficiency of the phenol sorption using conventional and non-conventional sorbents was determined. Phenol sorption proceeded to a greater extent on the ash produced during the gasification process than on the dried sludge subjected to heat treatment. The adsorption equilibration depended also on the absorbent material. Moreover, the increase of initial phenol concentration corresponded to the increase of phenol sorption. The goodness of fit of the theoretical adsorption isotherm (according to the Langmuir or Freundlich equations) to experimental data in the tested range of phenol concentrations (from 60 to 90 mg/dm3) depended on the tested sorbent material. In the case of phenol sorption on the ash the determination coefficients for both isotherms were similar, and in the case of the dried sludge better determination coefficient was obtained for the Freundlich isotherm. The analysis of the isotherm coefficients confirmed high sorption of phenol on the ashes as in the previous studies. Phenol sorption capacity on the sorbents tested in this study was greater than for the other unconventional adsorbents (bagasse fly ash, neutralized red mud, olive pomace) only in the case of ash. The tested sorbent materials released primary organic and inorganic substances on the contact with deionized water. The intensity of this phenomenon was greater for the dried sludge than for the ash. The increase of the toxic effect of the solution of this material was also observed. These studies, however, require continuation for better understanding of this phenomenon.