Possibility of Using Natural Zeolite Waste Granules Obtained by Pressure Agglomeration as a Sorbent for Petroleum...

Increasing incidents of oil spills and dynamic development of civilization are driving the demand for sorbents. The production of the overwhelming majority of mineral sorbents involves the highly energy-consuming calcination process with CO₂ emissions impacting the environment. Taking into account the environmental issues related to greenhouse gas emissions, we are in urgent need of green products and green technologies. The aim of this study was to investigate the possibility of using natural zeolite dust waste to produce oil sorbents in non-calcination technology. The main advantage of the proposed solution is reduction of greenhouse gas emissions and transformation of the waste material into green, useful product. The scope of the research covered the experimental tests for compaction of the zeolite material from Ukraine and Slovakia in a roller press with different type of binding agent and the performance tests for assessing the suitability of the produced agglomerates as a petroleum sorbent. In order to evaluate the agglomerates' properties, textural-structural analysis (optical microscopy, SEM microscopy, and low-temperature N₂ sorption), petroleum sorption (Westinghouse method), and physical-mechanical tests (resistance to gravitational drop, abrasion resistance) were carried out. Properties of the manufactured agglomerates were studied in comparison to commercial sorbent DAMSORB, commonly used in Poland. The test results showed that it is doable to produce the effective surface oil-spill sorbent from zeolite waste dust in a roller press by applying the relevant binding agent. The main finding of this study was that optimum feed composition for dry granulation that provides the granular sorbent with the best properties was established: 6% of C binder and moisture content within a narrow range of 20-20.6%. The C-1 sorbent achieved the highest and closely comparable to commercial sorbent parameters of petroleum sorption and drop strength, which are key points of this study. The absorption efficiency of petroleum substances for C-1 sorbent is 8% lower than that of a commercial sorbent, and resistance to gravitational drop is lower by only 3%. However, commercial sorbent exhibited better abrasion resistance compared to produced agglomerates, which is a compelling reason to continue the research in order to enhance the abrasion performance of the manufactured granules. The effectiveness of the dust consolidation method carried out was proved by textural parameters of the obtained zeolite-based sorbents. Specific surface area (S_BET) of B-2 (S_BET = 28.1 m²/g) and C-2 (S_BET = 28.3 m²/g) sorbents was very similar to the commercial sorbent (S_BET = 28.1 m²/g). Interestingly, all granules produced from clinoptilolite dust from Slovakia (A-2, B-2, C-2) achieved an increase of 19%, 33%, and 35%, respectively, in volume of mesopores, compared to the commercial sorbent. Moreover, the presented granulation technology favorably affected the size of the specific surface area as well as volume and surface area of mesopores in the case of obtained zeolite-based sorbent A-1 and B-1, compared with the starting raw material. Zeolite-based sorbent A-1 and B-1 achieved an increase of 17% and 18%, respectively, in specific area surface and an increase of 35% and 12%, respectively, in mesopores volume, compared with the raw material. Finally, the results of this investigation proved that it is possible to produce the efficient oil sorbent in a much more eco-friendly and green way, compared with that of the commercial sorbent.