Environmental-Friendly Modifications of Zeolite to Increase Its Sorption and Anion Exchange Properties, Physicochemical Studies of the Modified Materials

Taddesse A, Kibret K, Wogi L. Effects of natural and modified zeolite based composite fertilizers on slow release and nutrient use efficiency

Excessive use of chemical fertilizers causes serious environmental hazards, as only a fraction is really adsorbed by the soil. As part of the solution, the feasibility of using unmodified (UNZC) and surfactant-modified natural zeolite-based composite (SMNZC) fertilizers as support materials for the provision of nutrients to soil on a slow release basis was assessed using column and pot experiments. The characterization of the zeolite materials was done using powder XRD, XRF, SEM, BET, and TGA instruments. The percentage of cationic nutrients released from soil columns containing UNZC increased over time. Their release from SMNZC initially slowed down and became stable as the number of days increased. The percentage of N-NO3- and available P released from UNZC has constantly decreased with time. Their release from SMNZC increased as the number of days increased. The maximum P uptake by maize was observed for the soil treated with SMNZC, and there was no significant difference at all rates. The maximum uptake of Ca (3663.40 ppm), Mg (2617.34 ppm), and Fe (222.83 ppm) was observed at 250 kg/ha of UNZC. The highest uptake of K, Zn, and Cu was also observed for the soil amended with UNZC, irrespective of its application rate. Application of UNZC and SMNZC at the same rate equally affected total nitrogen uptake. Thus, this finding showed that UZNC is a better carrier of cationic nutrients, while SMNZC is preferable for the slow release of NO3- and available P. In conclusion, both the modified and unmodified support forms showed better performance than conventional fertilizer in delivering nutrients slowly and sustainably.

The potential of zeolite nanocomposites in removing microplastics, ammonia, and trace metals from wastewater and their role in phytoremediation

Nanocomposites are emerging as a new generation of materials that can be used to combat water pollution. Zeolite-based nanocomposites consisting of combinations of metals, metal oxides, carbon materials, and polymers are particularly effective for separating and adsorbing multiple contaminants from water. This review presents the potential of zeolite-based nanocomposites for eliminating a range of toxic organic and inorganic substances, dyes, heavy metals, microplastics, and ammonia from water. The review emphasizes that nanocomposites offer enhanced mechanical, catalytic, adsorptive, and porosity properties necessary for sustainable water purification techniques compared to individual composite materials. The adsorption potential of several zeolite-metal/metal oxide/polymer-based composites for heavy metals, anionic/cationic dyes, microplastics, ammonia, and other organic contaminants ranges between approximately 81 and over 99%. However, zeolite substrates or zeolite-amended soil have limited benefits for hyperaccumulators, which have been utilized for phytoremediation. Further research is needed to evaluate the potential of zeolite-based composites for phytoremediation. Additionally, the development of nanocomposites with enhanced adsorption capacity would be necessary for more effective removal of pollutants.

Thermal Properties of Illite-Zeolite Mixtures up to 1100 °C

Illitic clays are the commonly used material in building ceramics. Zeolites are microporous, hydrated crystalline aluminosilicates, they are widely used due to their structure and absorption properties. In this study, illitic clay (Füzérradvány, Hungary) was mixed with natural zeolite (Nižný Hrabovec, Slovakia) with up to 50 wt.% of zeolite content. The samples were submitted to thermal analyses, such as differential thermal analysis, differential scanning calorimetry, thermogravimetry, and dilatometry. In addition, the evolution of thermal diffusivity, thermal conductivity, and specific heat capacity in the heating stage of firing were measured and discussed. The amount of the physically bound water in the samples increased along with the amount of zeolite. The temperature of the illite dehydroxylation (peak temperature) was slightly shifted to lower temperatures, from 609 °C to 575 °C (for sample IZ50). On the other hand, the mass loss and the shrinkage of the samples significantly increased with the zeolite content in the samples. Sample IZ50 reached 10.8% shrinkage, while the sample prepared only from the illitic clay contracted by 5.8%. Nevertheless, the temperature of the beginning of the sintering (taken from the dilatometric curves) decreased from 1021 °C (for illitic clay) to 1005 °C (for IZ50). The thermal diffusivity and thermal conductivity values decreased as the amount of zeolite increased in the samples, thus showing promising thermal insulating properties.