Indonesia’s growing leather industry relies heavily on chrome tanning, a process that yields high-quality products but leaves 30\u201340% of the applied chromium as hazardous wastewater. Although trivalent chromium (Cr(III)) is relatively stable, environmental factors and oxidizing agents can convert it into hexavalent chromium (Cr(VI)). Unlike its trivalent counterpart, Cr(VI) is highly soluble, mobile, and extremely toxic, posing severe carcinogenic and mutagenic risks to both human health and the environment, making effective wastewater treatment crucial.<\/p>\n\n\n\n
To combat this pollution, adsorption<\/strong> has emerged as a highly effective and cost-efficient treatment method. Synthetic Zeolite Y<\/strong> is a promising adsorbent due to its thermal stability and high ion-exchange capacity; however, it struggles to attract Cr(VI) because the pollutant primarily exists as anions (such as HCrO4<\/sub>, Cr2<\/sub>O7<\/sub>, and CrO4<\/sub>). To overcome this poor affinity, researchers modify the zeolite by immobilizing zero-valent iron nanoparticles (nZVI) on its surface. The nZVI actively reduces the toxic Cr(VI) into safer Cr(III) which then precipitates as Cr(OH)3<\/sub> while the zeolite structure prevents the nanoparticles from clumping together.<\/p>\n\n\n\n Traditionally, nZVI is synthesized using hazardous and expensive chemicals like NaBH4<\/sub>, but recent advancements favor a sustainable green synthesis approach. By using green tea extract, which is rich in biodegradable polyphenols, researchers can safely reduce and stabilize the nanoparticles without generating toxic byproducts or requiring harsh reaction conditions. Applying these eco-friendly principles, Zeolite Y\/nZVI composites were successfully synthesized to enhance Cr(VI) adsorption, and their performance, along with their structural properties, was thoroughly evaluated through advanced characterization techniques like XRD, FTIR, and SEM-EDX.<\/p>\n\n\n\n The preparation of the composite material began with the green extraction of polyphenols by heating 20 g of dried tea in 200 mL of deionized water at 80\u00b0C for 60 minutes, followed by filtration. To synthesize the Zeolite Y\/nZVI composite, 4 g of Zeolite Y was mixed with 50 mL of 0.1 M FeCl3.<\/sub>6H2<\/sub>O and stirred for 30 minutes. Subsequently, 50 mL of the green tea extract was added dropwise as a natural reducing agent to form a black suspension, which was then centrifuged, washed with deionized water and ethanol, and finally dried in a vacuum desiccator at 34\u00b0C to prevent oxidation.<\/p>\n\n\n\n To confirm the successful synthesis and understand the properties of the material, various characterization techniques were employed before and after adsorption. X-ray diffraction (XRD) verified the crystal structure within a $2\\theta$ range of 5\u201350\u00b0, while Fourier-transform infrared (FTIR) spectroscopy analyzed the functional groups. Furthermore, SEM-EDX provided insights into the surface morphology and elemental composition, a particle size analyzer (PSA) measured the nanoparticle dimensions, and the point of zero charge (pHpzc) was determined to identify the specific pH at which the adsorbent’s surface is neutrally charged.<\/p>\n\n\n\n Batch adsorption experiments were systematically conducted to evaluate the efficacy of the Zeolite Y\/nZVI composite in removing Cr(VI) from aqueous solutions. A standard dosage of 0.05 g of the adsorbent was tested against several optimized parameters to find the ideal adsorption conditions. These parameters included varying the solution pH (1 to 9), operating temperatures (303 K to 343 K), initial Cr(VI) concentrations (10 ppm to 50 ppm), and contact times (5 to 90 minutes), with the residual Cr(VI) measured using a UV-vis spectrophotometer at a wavelength of 540 nm.<\/p>\n\n\n\n Finally, the experimental data were extensively analyzed using mathematical models to determine the underlying adsorption mechanisms. Thermodynamic parameters including changes in Gibbs free energy, enthalpy, and entropy were calculated to assess the spontaneity of the process. Additionally, the adsorption capacity data and equilibrium concentrations were fitted into Langmuir and Freundlich isotherm models to understand surface interactions, while pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were used to evaluate the adsorption kinetics.<\/p>\n\n\n\n The modification of Zeolite Y with nZVI enhanced its performance in reducing Cr(VI) concentration. The adsorption capacity of Zeolite Y increased from 0.9 mg\/g to 7.1 mg\/g. The temperature and pH strongly influenced the adsorption of Cr(VI) by Zeolite Y\/nZVI. A temperature increase improved the adsorption capacity, with the highest value of 10.22 mg\/g observed at 343 K. Cr(VI) adsorption by Zeolite Y\/nZVI was optimal under acidic conditions, particularly at pH 1. Based on the results obtained, Zeolite Y\/nZVI has the potential to be applied on a larger scale for the reduction of Cr(VI) levels.<\/p>\n\n\n\n Author: Yanuardi Raharjo, Ph.D.<\/p>\n\n\n\n Detailed information from this research can be seen in our article at: Nur Fariha Mahmuda, Yanuardi Raharjo, Tokok Adiarto, Handoko Darmokoesoemo, Heru Pramono and Ahmad Fauzi Ismail<\/p>\n\n\n\n Green-synthesized zeolite Y-supported zero-valent iron nanocomposite for enhanced adsorptive reduction of hexavalent chromium from aqueous solutions, RSC Advances, 2026, 16, 26155-26164.<\/p>\n\n\n\n https:\/\/ DOI: 10.1039\/d5ra09655c<\/p>\n\n\n\n <\/p>\n","protected":false},"excerpt":{"rendered":" Indonesia’s growing leather industry relies heavily on chrome tanning, a process that yields high-quality products but leaves 30\u201340% of the applied chromium as hazardous wastewater. Although trivalent chromium (Cr(III)) is relatively stable, environmental factors and oxidizing agents can convert it into hexavalent chromium (Cr(VI)). Unlike its trivalent counterpart, Cr(VI) is highly soluble, mobile, and extremely […]<\/p>\n","protected":false},"author":79,"featured_media":382658,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[49,14616],"tags":[15014,14538,168],"class_list":["post-402595","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scientific-article","category-scientific-article-en","tag-publication","tag-research","tag-universitas-airlangga-en"],"yoast_head":"\n
https:\/\/pubs.rsc.org\/en\/content\/articlelanding\/2026\/ra\/d5ra09655c<\/p>\n\n\n\n