Reuse potential of functionalized thermoplastic waste as reinforcement for thermoset polymers: Mechanical properties and erosion resistance

Two types of polymer waste materials, poly(ethylene terephthalate) (PET) and polycarbonate based Colombian Resin (CR-39), were used for the designing of fully recycled composite materials. Waste PET was employed for the synthesis of thermoset unsaturated polyester resin (UPR), while CR-39 was used as reinforcement in the UPR matrix. Prior to mixing, CR-39 particles were subjected to oxidation and chemical activation using acids/base and ethanol amine, respectively. The effect of the modifier type and variable loading of the activated CR-39 particles on mechanical and dynamic-mechanical properties of the corresponding composites was investigated. The greatest improvement in the tensile and flexural strength of UPR resin was achieved with the composite containing 0.5 wt% of amine activated filler particles, 96.0% and 62.2%, respectively. The Arrhenius equation was used to calculate the activation energy for glass transition from dynamic mechanical properties measured at various frequencies. The activation energy of the main transition for UPR resin and composites were calculated to be 173 and 350 kJ center dot mol(-1) indicating that reinforcement results in an increase in the energy barrier to macromolecules viscoelastic relaxation. In addition, erosion resistance was studied during exposure of samples to cavitation tests. According to the obtained results, these materials can be applied in construction and mining industry

Vermiculite enriched by Fe(III) oxides as a novel adsorbent for toxic metals removal

Expanded vermiculite (EV) was modified by deposition of different spinel ferrite composites on the outer surface of EV 2:1 layers in order to improve its adsorptive properties. Modifications were made by deposition of: magnetite, manganese ferrite, cobalt ferrite and chromium oxide/hematite. The characterization of modified materials was performed by: scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) methodology, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), magnetization measurements, as well as determination of cation exchange capacity (CEC) and pH point of zero charge (pHPZC). Obtained samples were used as adsorbents for Pb2+, Ni(2+)and Cd2+ ions from an aqueous solution in a batch system. Results showed that adsorption capacity was strongly dependent on physical and chemical changes induced by specific chemical modification. Hydrothermally produced manganese and cobalt ferrites caused significant surface changes and altered the interlayer cation balance. Among the others, EV-Mn/Co-ferrite(s) samples possessed the highest adsorption capacity towards Ni2+ (33.06 mg g(-1)), along with an increase of the CEC. Freundlich's adsorption isotherm model provided the best fit of obtained experimental data, while kinetic studies showed that the adsorption rate follows the pseudo second-order model, implying heterogeneous adsorbents surface. Thermodynamic and kinetic parameters indicated that the mechanism of cations removal efficacy was dominantly followed by the ion exchange. This study confirmed that doped ferrites, produced by solvothermal method, improve surface properties of EV and increase adsorption potentials towards heavy metals

Kinetics and column adsorption study of diclofenac and heavy-metal ions removal by amino-functionalized lignin microspheres

In-depth kinetic and column adsorption study for diclofenac, DCF, heavy-metal and oxyanions adsorption on highly effective amino-functionalized lignin-based microsphere adsorbent (A-LMS) is examined. The A-LMS was synthesized via inverse suspension copolymerization of industrial kraft lignin with the amino containing grafting-agent (polyethylene imine), and an epoxy chloropropane cross-linker. The batch adsorption results indicated process spontaneity and feasibility of a high removal capacity: DCF(151.13) >>Cd2+(74.84)>Cr(VI)(54.20)>As(V)(53.12)>Ni2+(49.42 mg g(-1)). The quantum chemical calculated interaction energies reveal stabilization of the A-LMS/DCF complex through the electrostatics and van der Waals interactions. The results from the pseudo-second order and Weber-Morris fitting indicate a fast removal rate; thus, column tests were undertaken. The single resistance mass transfer model, i.e. the mass transfer (kfa) and diffusion coefficient (Deff), shows pore diffusional transport as a rate limiting step. The fitting of the fixed bed column data with empirical models demonstrates the influences of flow rate and adsorbate inlet concentration on the breakthrough behavior. Pore surface diffusion modeling (PSDM) expresses mass transport under applied hydraulic loading rates, calculated breakthrough point adsorption capacities: Cd2+(58.1)>Cr(VI)(54.1)>As(V)(50.9)>>Ni2+(42.9 mg g(-1))), without performing the experimentation on a full pilot-scale level, further confirms the high applicability of the A-LMS biobased adsorbent