The paper presents the results of a pilot-scale study investigating the efficiency of an ion exchange resin system in the removal of Ni, Hg, and Cr from flue gas desulphurisation wastewater, in the presence of competitive metals such as Ca, Mg, Al, Fe, and Mn. The core part of the ion exchange installation consisted of two columns that were filled with ion exchange resin with iminodiacetic functional groups (Purolite S930) and one column filled with resin with isothiouronium functional groups (Purolite S920). The results showed that Ni, Hg, and Cr were almost completely removed from the wastewater with nearly 100% efficiency. Purolite S930 almost totally removed Ni, reducing its content from 89.3 ± 35 μg dm⁻³ to below 0.1 μg dm⁻³, while Purolite S920 reduced the remaining Cr content from 2.2 ± 0.6 μg dm⁻³ and most of the Hg content, from 23.5 ± 6.6 μg dm⁻³ to below 0.1 μg dm⁻³. The competitive metals Ca, Mg, Mn, and Al showed low affinity to the studied ion exchange resins. The study also assessed speciation of ion forms and sorption mechanisms. Breakthrough curve analysis was also carried out, which revealed that the selectivity sequence of iminodiacetic resin was Ni > Cr > Hg > Fe > Al > Mn > Ca, Mg. Elution studies were performed on S930 resins that allowed the separation of two streams: one containing mostly Ni and Fe which can be subjected to Ni recovery and the other containing mostly Cr and Hg which can be separated.

The adsorption process of cadmium ions (Cd), manganese ions (Mn) and lead ions (Pb) onto the spent coffee grounds (SCG) and activated spent coffee grounds (biochar, A-SCG) was investigated. The SCG activation was carried out in the pyrolysis process in a fluidized bed reactor. scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) measurements and CHN analysis were used in order to define the differences between biomaterials. In the study the different mass of materials (0.2–0.5 g) and constant heavy metal volume and concentration (20 cm3/100 ppm) were investigated on the adsorption process. In order to describe the sorption parameters the Langmuir, Freundlich and Temkin isotherms were used. The maximum adsorption for biochar reached 22.3 mg/g for Pb ions, 19.6 mg/g for Mn ions and 19.4 mg/g for Cd ions which were noticeably higher than the results obtained for spent coffee grounds which reached 13.6 mg/g for Pb ions, 13.0 mg/g for Mn ions and 11.0 mg/g for Cd ions. Metal ion adsorption on both SCG and A-SCG was best described by the Langmuir model, thus chemisorption was a dominant type of adsorption. Studying the kinetics of the sorption process, one can see that the process is of a chemical nature according to the best fit of the pseudo-second rate order model. The obtained results show that the chosen sorbents can be used for the removal of cadmium, manganese and lead compounds from aqueous solutions with high efficiency.

This article presents flame retardant compounds for silicone rubber (SR) in the form of polyhedral oligomeric silsequioxanes (POSS), containing both isobutyl groups and amino-propyl (AM-POSS) or chloro-propyl group (HA-POSS) or vinyl groups (OL-POSS). Silsequioxanes were incorporated into the silicone rubber matrix in a quantity of 3 and 6 parts by wt by the method of reactive stirring with the use of a laboratory mixing mill. Based on the analyses performed by TG (Thermogravimetry) FTIR (Fourier Transform Infrared Spectroscopy), conical calorimeter, and SEM-EDX (Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy) methods, the thermal degradation mechanism of non-cross-linked and cross-linked silicone rubber has been elucidated. The effects of POSS, and POSS in a synergic system with melamine polyphosphate (MPP), on the thermal properties and flammability of silicone rubber composites were presented. Based on the test results obtained, a mechanism of flame retardant action POSS and POSS-MPP has been proposed. It has been shown that POSS, especially with MPP, considerably increases the thermal stability and decreases the flammability of the SR rubber composites under investigation.