Optimization of Parameters and Methodology for the Synthesis of LTA-Type Zeolite Using Light Coal Ash

Opportunities for Recycling PV Glass and Coal Fly Ash into Zeolite Materials Used for Removal of Heavy Metals (Cd, Cu, Pb) from Wastewater

This work shows the development and characterization of two zeolite structures by recycling PV glass and coal fly ash for the removal of cadmium, copper, and lead from synthetic solutions containing one or three cations. The materials were characterized in terms of crystalline structure (XRD), morphology (SEM, AFM), and specific surface. For increasing the heavy-metals removal efficiency, the adsorption conditions, such as substrate dosage, preliminary concentration, and contact time, were optimized. The pseudo-second-order kinetic model adsorption kinetics fit well to describe the activity of the zeolites ZFAGPV-A and ZFAGPV-S. The zeolite adsorption equilibrium data were expressed using Langmuir and Freundlich models. The highest adsorption capacities of the ZFAGPV-A zeolite are q_maxCd = 55.56 mg/g, q_maxCu = 60.11 mg/g, q_maxPb = 175.44 mg/g, and of ZFAGPV-S, are q_maxCd = 33.45 mg/g, q_maxCu = 54.95 mg/g, q_maxPb = 158.73 mg/g, respectively. This study demonstrated a new opportunity for waste recycling for applications in removing toxic heavy metals from wastewater.

Interzeolitic Transformation of Clinoptilolite into GIS and LTA Zeolite

A natural clinoptilolite zeolite was transformed into other zeolites of greater industrial interest, such as zeolites with GIS and LTA structures. The synthesis conditions were studied, and the interzeolitic transformation was characterized by X-ray diffraction (XRD), X-ray fluorescence (FRX), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). From the results, it was possible to observe that the GIS and LTA zeolites were successfully synthesized. Furthermore, the results revealed that a synthesis time of 4 days was enough to obtain the GIS structure, and 4 h was sufficient to obtain LTA. The interzeolitic transformation can be explained by the RBU (Ring Building Unit) approach using C4 units from the HEU topology. The use of clinoptilolite in the synthesis of other zeolites is an innovative, economically viable, and environmentally sustainable process that exploits a material that exists in large quantities and is still little explored by industry.

Renewable Diesel Production from Palm Fatty Acids Distillate (PFAD) via Deoxygenation Reactions

The reactions to produce liquid biofuels from a palm fatty acid distillate (PFAD) under hydrogen absence were carried out using 10 wt% NiO/zeolite (Ni/Zeo), 10 wt% Co3O4/zeolite (Co/Zeo), and 10 wt% (NiO + Co3O4)/zeolite (NiCo/Zeo) as catalysts. The zeolite was synthesized by a thermal and chemical treatment from natural clay, obtaining a zeolite A and sodalite mixture. Catalytic activity was evaluated as a function of reaction temperature (250, 300, and 350 °C) during 0.5 h and using 5 wt% of catalyst. The reaction products were classified as organic liquid products (OLPs), gaseous products, and solid waste. The OLPs fractions were separated by fractional distillation, and the products were identified and quantified using gas chromatography coupled to a mass spectrometer detector (GC-MS). The results showed yields to OLPs above 50% for all catalysts and temperatures. However, the highest yield to OLPs of 67.9% was reached with a NiCoZeo catalyst at 300 °C. In this reaction, a higher yield to hydrocarbons was obtained (84.8%), indicating a cooperative effect between Ni and Co in the catalyst. Hydrocarbons such as heptadecane (C17H36), pentadecane (C15H26), and other alkanes-alkenes with lower carbon chains were the main products. Therefore, deoxygenation of PFAD using a low-cost Ni-Co catalyst was shown to be an economic and viable way to produce diesel-type biofuels.