Hexavalent chromium is associated mainly with industrial activities and can enter water through wastewater from metal processing, mining, smelting, electroplating and related operations. Unlike many organic pollutants, heavy metals do not biodegrade and can persist in water, sediments and soils for long periods. Cr(VI) is particularly concerning because of its mobility and toxicity; prolonged or substantial exposure can contribute to inflammation, cancer and severe biological damage. Adsorption is widely investigated as a treatment strategy because it can be efficient and comparatively simple: contaminants attach to the surface of a solid material and are then removed with it. Biochar, a carbon-rich product made from biomass, is attractive because its feedstocks are renewable and inexpensive. Its performance, however, depends strongly on surface chemistry, pore structure and preparation conditions. The tea-waste study sought to improve those characteristics while also making the material easier to recover after treatment.

The researchers collected a mixture of spent green and black tea leaves after extraction and filtration at a tea-beverage factory in Xinyang, Henan Province, China. The wet material was washed, air-dried for 48 hours and ground into a fine powder. To produce the magnetic biochar, they combined five grams of tea powder with ferric chloride, zinc chloride and a five-percent urea solution in water. Zinc chloride acted as a pore-forming agent, urea supplied nitrogen, and ferric chloride provided iron for magnetization and additional reactive sites. The mixture was treated in a hydrothermal reactor, where biomass is carbonized in hot, pressurized water rather than in the oxygen-limited, higher-temperature conditions commonly associated with pyrolysis. This route is useful for wet biomass because it can reduce the energy needed for extensive pre-drying. The resulting solid was filtered, washed until neutral and dried before testing.

To identify the most effective processing window, the team varied the hydrothermal temperature between 180 and 220 degrees Celsius and the treatment time between four and 18 hours. Response surface methodology, a statistical optimization technique, was used to evaluate how those variables affected surface area and chromium removal. The models were statistically strong, with coefficients of determination of 0.9743 for surface area and 0.9705 for removal efficiency. Temperature had a greater effect than reaction time on both outcomes. The best overall preparation condition was 200 degrees Celsius for four hours, producing the material designated NMTB-200. This result illustrates why processing conditions matter for biochar: raising the temperature can open pores and release volatile components, but excessive heating can also damage or collapse parts of the carbon structure. At 220 degrees Celsius, the material’s performance declined rather than continuing to improve.

Microscopic and spectroscopic tests showed how the chemical treatment altered the tea-derived carbon. Untreated tea biochar had a relatively dense and smooth surface, whereas nitrogen-modified and nitrogen-iron-modified samples developed rougher, more visibly porous structures. The specific surface area of NMTB-200 reached 25.177 square meters per gram, compared with 7.185 square meters per gram for the pristine tea biochar. X-ray diffraction identified iron oxide phases, including magnetite, Fe3O4, and hematite, in the modified material. Fourier-transform infrared spectroscopy detected carbon-nitrogen and iron-oxygen groups, while X-ray photoelectron spectroscopy confirmed nitrogen and iron on the surface. NMTB contained 6.33 atomic percent nitrogen and 3.4 atomic percent iron in the reported surface analysis. Magnetic measurements showed that saturation magnetization increased with preparation temperature, reaching 5.95 electromagnetic units per gram for NMTB-220. Although NMTB-200 was not the most strongly magnetic sample, its balance of porosity and surface chemistry produced the best chromium uptake.

In controlled adsorption tests, the material’s performance depended on dosage, chromium concentration, contact time and pH. At a dose of 0.1 gram in 50 milliliters of a 50-milligram-per-liter Cr(VI) solution, NMTB-200 achieved 96.90 percent removal. Increasing the amount of biochar beyond the optimum raised the total number of available sites but reduced the adsorption capacity calculated per gram, partly because particles became less effectively dispersed and individual sites were not used as efficiently. As the starting chromium concentration increased, the amount captured per gram rose because more chromium was available to occupy active sites, but the percentage removed fell as those sites approached saturation. Uptake increased rapidly during the early stages of contact and began to level off after roughly six hours. The material performed best under strongly acidic conditions, with its capacity decreasing as pH rose from two to seven. At low pH, protonated surface groups carry positive charge and attract negatively charged chromate species such as HCrO4− and Cr2O7²−.

Equilibrium and rate analyses pointed to a chemically active surface rather than simple physical trapping. The Langmuir model described the data better than the Freundlich model, suggesting that adsorption was dominated by a relatively uniform layer of chromium-bearing species on available sites. The pseudo-second-order model provided the better kinetic fit, although the researchers noted that such a fit alone cannot conclusively prove chemisorption. Additional evidence came from spectroscopy, surface-charge measurements, chromium speciation and computational modeling. After treatment, the biochar surface contained both Cr(VI) and Cr(III), but Cr(III) was the dominant form detected by X-ray photoelectron spectroscopy. In the NMTB-200 experiment, the concentration of Cr(VI) in solution fell from 50 to 5.04 milligrams per liter, while approximately 7.72 milligrams per liter of Cr(III) remained in solution and the rest of the removed chromium was associated with the solid phase. These results indicate that the material does more than attract chromium: it helps reduce the more hazardous hexavalent form to trivalent chromium and then immobilizes the product.

The proposed mechanism unfolds in three connected stages. First, under acidic conditions, positively charged sites on the protonated biochar draw anionic Cr(VI) species toward the surface through electrostatic attraction. Next, electron transfer at iron-, nitrogen- and oxygen-containing sites reduces part of the Cr(VI) to Cr(III). Finally, the reduced chromium forms surface complexes with functional groups in the carbon matrix, including sites associated with nitrogen and iron-oxygen bonds. Density functional theory calculations supported this interpretation: the calculated adsorption energy for chromium at iron and nitrogen sites in NMTB was −3.409 electron volts, compared with −3.201 electron volts for corresponding sites in unmodified tea biochar. The stronger interaction and more pronounced charge transfer predicted for the modified material help explain why it performed well despite having a moderate surface area compared with some engineered adsorbents. In practical terms, the iron particles also offer a route to recover the spent material from water using a magnetic field.

Repeated-use tests provided an early indication of the material’s durability. NMTB-200 was regenerated with sodium hydroxide and reused five times; removal efficiency declined from 99.95 percent in the first cycle to 84.49 percent after the fifth. Iron release remained low, with dissolved iron concentrations below 1.32 milligrams per gram across the cycles, suggesting that much of the iron was retained within or strongly attached to the carbon structure. The researchers also tested a farmland surface-water sample containing 0.0454 milligrams per liter of Cr(VI). After 24 hours, the concentration fell to 0.0016 milligrams per liter, corresponding to 96.55 percent removal. The findings remain laboratory and small-scale demonstrations rather than proof of immediate treatment-plant readiness. Future work will need to assess higher chromium loads, competing ions, larger flow systems, regeneration chemistry, residual zinc and long-term stability. Even so, the one-step process demonstrates a compelling circular-economy concept: a wet, abundant beverage waste can be converted into a recoverable adsorbent that both captures Cr(VI) and promotes its chemical transformation into a less toxic form.

An important scientific feature of the work is that chromium removal was evaluated as both a separation and a chemical-transformation problem. Measuring total chromium alone could make adsorption appear successful even if the contaminant remained in a mobile or hazardous form. By combining solution measurements with surface-sensitive spectroscopy and chromium speciation, the study could distinguish chromium retained on the biochar from chromium that remained dissolved after reduction. That distinction is especially relevant for assessing treatment safety, because a material that transfers contaminants between phases without stabilizing them would provide limited environmental benefit.

The optimization results also illustrate a broader challenge in designing biomass-derived adsorbents. A preparation condition that increases magnetic content or produces more severe carbonization is not necessarily the one that delivers the best overall treatment. Adsorption performance reflects a balance among accessible pores, surface functional groups, iron-containing phases, charge behavior and the stability of those features in water. The researchers’ combined use of response-surface modeling and material characterization therefore connects manufacturing variables with chemical function rather than treating the biochar as an interchangeable carbon powder. Before such a material could be considered for continuous treatment, further testing would be needed in waters containing competing ions and fluctuating acidity, as well as studies of spent-adsorbent handling. The retained chromium and any dissolved iron or other residual process chemicals would need to be managed alongside the treated water itself.

Subject of Research: Tea waste-derived magnetic biochar for hexavalent chromium removal from water

Article Title: One-step synthesis of magnetic tea waste biochar for efficient hexavalent chromium adsorption: process optimization, characterization, and adsorption mechanism

Article References: Guo, S., Wang, P., Zhu, Y., Zhou, Y., Li, M., Lin, X., Xu, P., & Sun, M. (2026). One-step synthesis of magnetic tea waste biochar for efficient hexavalent chromium adsorption: process optimization, characterization, and adsorption mechanism. Journal of Saudi Chemical Society, 30(5), Article 63. https://doi.org/10.1007/s44442-026-00114-5

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00114-5

Keywords: tea waste, magnetic biochar, hexavalent chromium, water treatment, hydrothermal carbonization, adsorption, nitrogen doping, iron oxide, circular economy, One-step, synthesis, magnetic

The work addresses a persistent challenge in drug discovery: finding molecules that combine biological activity with practical, efficient and comparatively sustainable synthesis. Spiro compounds contain two ring systems joined through a single shared atom, creating a three-dimensional structure that can help molecules occupy biological binding sites in ways that flatter, more flexible compounds may not. Benzothiazoles, which contain fused benzene and thiazole rings, are also widely studied because their nitrogen and sulfur atoms can participate in interactions with proteins and other biomolecules. Combining these features creates a rigid, information-rich scaffold, but assembling such molecules can require multiple steps, long heating periods and substantial solvent use. The researchers therefore designed a multicomponent reaction that brings three starting materials together in a single vessel: 11H-indeno[1,2-b]quinoxalin-11-one, a substituted 2-aminobenzothiazole and isatoic anhydride. Potash alum was added as the catalyst, ethanol served as the solvent, and the mixture was irradiated at 600 watts in a microwave reactor while being stirred.

Optimization experiments showed why the final protocol performed better than the initial conditions. Without a catalyst, ethanol gave a 56% yield after 10 hours of conventional heating and a 59% yield after 40 minutes of microwave irradiation. Adding 20 mol% potash alum under conventional heating raised the yield to 67% and shortened the reaction time to six hours. Under microwave conditions, increasing the catalyst loading from 5 to 20 mol% progressively improved the yield, reaching 77% during the optimization sequence. At the selected catalyst loading, increasing microwave power from 400 to 600 watts improved conversion, while raising it further to 800 watts produced no meaningful gain. Extending irradiation from 10 to 20 minutes increased the model reaction yield from 80% to 95%. The researchers attributed the performance of ethanol partly to its polarity, microwave absorption and ability to solvate the reactants. Potash alum is proposed to activate the ketone and assist the sequence of bond-forming events that links the three components into the spirocyclic products. The resulting process uses a readily available catalyst and avoids the prolonged heating associated with the comparison method.

The chemical identity of the products was checked using several complementary analytical techniques rather than relying on yield alone. Fourier-transform infrared spectroscopy detected characteristic nitrogen–hydrogen, carbonyl, carbon–nitrogen and aromatic signals. Proton and carbon nuclear magnetic resonance spectroscopy provided evidence for the expected hydrogen and carbon environments, including resonances associated with the spiro carbon. Electrospray ionization mass spectrometry produced molecular-ion signals consistent with the proposed formulas. High-performance liquid chromatography was used to assess purity, which ranged from 92% to 99% across the reported compounds. The library incorporated a range of substituents on the benzothiazole ring, including nitro, methoxy, methyl, fluoro, bromo and chloro groups, as well as combinations of halogens. This systematic variation allowed the researchers to compare how changes in electronic character, size and lipophilicity affected the biological assays. The products were isolated as powders after cooling the reaction mixture, precipitation into ice-cold water and extraction with diethyl ether, followed by washing and drying.

The most striking biological result came from the MTT assay of cytotoxicity against MCF-7 breast cancer cells. The unsubstituted compound 3a provided a moderate baseline response, with an IC50 of 43.66 micromolar. Several substitutions performed poorly, including the methoxy derivative 3e and the methyl derivative 3f, both of which had IC50 values above 100 micromolar. A nitro group produced sharply different outcomes depending on its position: compound 3c showed an IC50 of 2.07 micromolar, whereas related compounds 3b and 3d were much weaker, with reported values of 92.15 and 24.66 micromolar, respectively. The standout was 3k, bearing both fluorine and bromine substituents, which reached 0.58 micromolar. For comparison, doxorubicin and cisplatin produced IC50 values of 1.03 and 4.61 micromolar, respectively, under the study’s conditions. The authors suggest that the paired electron-withdrawing halogens may improve activity partly by increasing lipophilicity. However, the test used a single cancer cell line and did not determine selectivity for cancer cells over healthy cells, mechanism of action or activity in animals. Those limitations mean that 3k should be viewed as a lead for investigation, not as a validated anticancer drug.

The antioxidant results revealed a contrasting structure–activity pattern. In the DPPH radical-scavenging assay, the unsubstituted compound 3a was the strongest performer, with a reported IC50 of 0.52 micromolar. The result suggests that preserving the parent aromatic and electronic arrangement favored the reaction with the stable radical used in the test. Most substitutions reduced activity substantially: compounds carrying nitro, methoxy, methyl or halogen groups generally had IC50 values above 100 micromolar. Compound 3d retained measurable activity at 35.47 micromolar, while the fluoro derivative 3g showed an IC50 of 83.45 micromolar. Ascorbic acid was included as the reference compound and had a reported IC50 of 17.56 micrograms per milliliter. Because the assay measures a chemical radical-scavenging reaction rather than antioxidant effects in a living organism, the result cannot by itself demonstrate therapeutic benefit. Still, the sharp difference between 3a and its substituted analogues gives the researchers a useful structure–activity clue: the modifications that enhanced the anticancer profile of 3k did not enhance its antioxidant performance.

The compounds also displayed activity against two Gram-positive bacteria in a Kirby–Bauer disk-diffusion assay. Compound 3d, containing a nitro group at the reported R4 position, produced the largest inhibition zone, measuring 18 millimeters against both S. aureus and B. subtilis. Compound 3e generated an 18-millimeter zone against B. subtilis, while 3f produced an 11.66-millimeter zone against the same organism. The dichloro derivative 3j showed a notable 11-millimeter zone against S. aureus, and several fluoro-, bromo- and chloro-substituted compounds showed moderate effects. The reference antibiotic ciprofloxacin produced inhibition zones of 21 to 24 millimeters in the reported comparisons. These results suggest that antibacterial activity depended on a different balance of electronic effects and lipophilicity from the one associated with cytotoxicity. In particular, a nitro group at one position was more favorable for bacterial inhibition than the same functional group at other positions. Since disk diffusion depends on both antimicrobial action and a compound’s ability to move through the assay medium, further tests would be needed to determine minimum inhibitory concentrations, activity against additional organisms and the underlying molecular targets.

Computational analysis provided a molecular explanation for why 3k, 3c and 3d emerged as leading candidates. The researchers docked the compounds into the breast cancer-associated protein structure identified by PDB code 3EQM using the Glide XP protocol. Compound 3k produced the most favorable reported docking score, −8.41957, together with a Glide energy of −53.911 kilocalories per mole. Compounds 3c and 3d also scored strongly, at −8.36215 and −8.21235, respectively, compared with −6.88115 for the protein’s co-crystallized ligand in the redocking comparison. The predicted interactions for 3k included a hydrogen bond involving a nitrogen atom in its quinoxalinone region, pi–pi stacking with tryptophan 224, hydrophobic contacts with valine, methionine and isoleucine residues, and a halogen bond involving bromine and arginine 375. A 100-nanosecond molecular-dynamics simulation suggested that the 3k–3EQM complex remained stable, with limited ligand fluctuation and persistent contacts, including a pi–pi interaction with tryptophan 224. QikProp calculations further indicated that the compounds met Lipinski’s rule of five, while 3k and 3j showed high predicted permeability and potential central nervous system exposure. These computational findings are useful for prioritizing experiments, but docking scores and in silico pharmacokinetics do not substitute for biochemical, cellular, toxicological or animal studies. The study’s central advance is therefore a practical synthesis and a set of testable leads whose activities can now be examined with more demanding models.

The study also illustrates why multifunctional screening can reveal trade-offs within one chemical series. The derivatives were not uniformly active across assays: structural changes that favored interaction with the breast cancer-associated protein did not necessarily improve radical scavenging or bacterial inhibition. This divergence is scientifically useful because it indicates that the scaffold can be tuned toward different biological objectives rather than treated as a single-purpose template. The reported antioxidant mechanism should nevertheless be interpreted cautiously. DPPH measures reaction with a stable laboratory radical and does not establish how a compound behaves in cells, where uptake, metabolism, redox cycling and toxicity can alter the outcome.

Further validation would need to connect the computational predictions with direct experiments. The proposed contacts between 3k and 3EQM could be tested through biochemical binding or inhibition studies, while broader cell panels could assess whether its effect is selective for MCF-7 cells. Additional antibacterial measurements, including minimum inhibitory concentrations, would distinguish growth inhibition from differences in diffusion through agar. The favorable ADME-Tox predictions are similarly prioritization tools rather than evidence of safe exposure in an organism. Even so, combining rapid synthesis, analytical confirmation, phenotypic assays and modeling gives the series a rational starting point for refining potency, selectivity and pharmacological behavior.

Subject of Research: Microwave-assisted synthesis and biological evaluation of spiro-benzothiazole derivatives

Article Title: Boosting microwave-assisted synthesis via potash alum for bioactive spiro-benzothiazoles with its computational profile

Article References: Gamit, A. S., Humal, T. R., Desai, P. S., Shaikh, F. M., Patel, N. B., Shah, A. B., Limbachiya, N. G., Prajapati, A., Patel, H. D., & Patel, V. M. (2026). Boosting microwave-assisted synthesis via potash alum for bioactive spiro-benzothiazoles with its computational profile. Discover Green Chemistry, 1(1), Article 25. https://doi.org/10.1007/s44509-026-00027-x

Image Credits: AI Generated

DOI: 10.1007/s44509-026-00027-x

Keywords: spiro-benzothiazoles, microwave chemistry, potash alum, green synthesis, anticancer compounds, antioxidant activity, antibacterial activity, molecular docking, Boosting, microwave-assisted, synthesis, potash

Cadmium is a toxic heavy metal released through activities including metal processing, electroplating, battery production, paint manufacturing, ceramics, printing, tanning, and textile and paper production. Once it enters waterways, it can persist and move through aquatic systems. Human exposure is particularly concerning because the kidneys are a major target of cadmium toxicity, and long-term exposure can impair renal function. The source study notes drinking-water limits of 5 micrograms per liter from the U.S. Environmental Protection Agency and 3 micrograms per liter from the World Health Organization, while the EPA limit for dissolved cadmium in freshwater is 1.8 micrograms per liter. Measuring concentrations near such thresholds requires more than simply placing a water sample into an instrument. Natural waters and industrial effluents contain dissolved salts, organic compounds, suspended matter, and other metals that can interfere with analysis. At the same time, the target ions may be below the direct detection capability of relatively accessible instruments such as FAAS. Separating and concentrating cadmium before measurement can address both problems by removing much of the sample matrix and increasing the analyte concentration.

The researchers chose SBA-15 as the foundation because its structure consists of an ordered network of mesopores and a large internal surface area. The silica surface is rich in silanol groups, written chemically as –OH, which can be used as attachment points for functional molecules. Unmodified SBA-15 provides space for adsorption, but its interactions with cadmium are not sufficiently selective or efficient for the intended application. CBIMMT adds nitrogen- and sulfur-containing sites capable of interacting with cadmium ions through coordination. In this design, the silica acts as a high-area scaffold while the ligand supplies much of the chemical recognition. The team synthesized SBA-15 using a block-copolymer template, tetraethyl orthosilicate as the silica source, hydrochloric acid, potassium chloride, and water. After formation, the template was removed with ethanol. The researchers then refluxed 2 grams of SBA-15 with 1 gram of CBIMMT in ethanol at 80 degrees Celsius for 24 hours. The modified solid was filtered and dried, producing the SBA-15/CBIMMT nano-sorbent examined in the study.

A suite of material-characterization techniques was used to determine whether the modification changed the structure and to verify that the ligand was present. Transmission electron microscopy showed that the synthesized SBA-15 had a consistent hexagonal mesoporous arrangement, with pore sizes below approximately 20 nanometers. Brunauer–Emmett–Teller, or BET, analysis measured a specific surface area of 397.4 square meters per gram for the original silica. After CBIMMT was added, the surface area fell to 351.6 square meters per gram, a change the researchers attributed to ligand coverage of the pore surfaces. The reduction is consistent with molecules occupying some of the available surface while leaving a substantial porous framework intact. Field-emission scanning electron microscopy indicated that CBIMMT covered the SBA-15 surface, while carbon, nitrogen, and sulfur detected by CHNS elemental analysis further supported the presence of the organic ligand. Energy-dispersive X-ray spectroscopy also identified the ligand-associated elements and, after adsorption, showed cadmium on the material. Thermogravimetric analysis revealed a 27.4 percent mass loss between about 272 and 394 degrees Celsius, attributed principally to removal of CBIMMT, with smaller losses associated with water and remaining organic components.

The analytical procedure was based on solid-phase extraction. In the optimized protocol, 100 milliliters of water containing cadmium was adjusted to pH 5 with an acetate buffer and mixed with 60 milligrams of the nano-sorbent. Shaking at room temperature for 20 minutes allowed cadmium ions to contact and bind to the ligand-functionalized surface. The solid was then separated by centrifugation at 8,000 revolutions per minute for five minutes. The captured ions were released with just 1 milliliter of 0.3-molar nitric acid, which disrupts the cadmium–ligand interactions and transfers the metal into a concentrated solution for FAAS measurement. The ratio between the original 100-milliliter sample and the final 1-milliliter eluent gives a preconcentration factor of 100. That concentration step is central to the method: a dilute signal distributed through a relatively large sample becomes a stronger signal in a small volume, while the extraction stage helps reduce matrix effects. The researchers investigated pH, sorbent quantity, contact time, eluent composition and concentration, sample volume, and salinity to establish these operating conditions.

pH controlled how effectively the material captured cadmium. Extraction increased as pH rose from 2 to approximately 5. Under strongly acidic conditions, the amine and sulfide groups of CBIMMT become protonated, making them less available to bind positively charged cadmium ions. Protons also compete with cadmium for the ligand’s active sites. At higher pH values, however, cadmium can begin forming hydroxide species or precipitates, making it harder to distinguish adsorption from other removal processes. The researchers therefore selected pH 5 as the practical optimum. Testing different sorbent masses showed that 60 milligrams captured the cadmium under the study conditions; adding more produced little additional improvement. The modified material’s extraction efficiency was more than twice that of unmodified SBA-15, highlighting the contribution of CBIMMT rather than surface area alone. Cadmium uptake changed little after 20 minutes of contact, so longer extraction was unnecessary. Among the acids tested for release, 0.3-molar nitric acid in a 1-milliliter volume provided quantitative elution. Extraction remained stable when sodium nitrate concentrations reached 0.5 molar, suggesting that the method can tolerate highly saline samples.

The material’s reported maximum adsorption capacity was 411 milligrams of cadmium per gram of nano-sorbent, calculated from equilibrium experiments using different initial cadmium concentrations. The researchers also assessed selectivity by adding potentially interfering ions to cadmium solutions. Most tested cations and anions caused no significant effect even when present at concentrations ten times higher than cadmium, with tolerance defined as a relative error within plus or minus 5 percent. In repeat measurements of a 100-nanogram-per-milliliter standard, the relative standard deviation was 1.6 percent. The reported limit of quantification was 12.3 nanograms per milliliter, calculated using the standard relationship between blank variability and calibration-curve slope. The sorbent could be reused three times after washing with the recovery solution, although adsorption declined from 98.6 percent initially to 95.1 percent after the third cycle. Possible reasons include particle loss during elution, leaching of attached ligand, or formation of strong complexes that are not completely reversed. These results indicate promising repeat use, while also identifying durability as an issue for future optimization.

To test performance beyond prepared solutions, the researchers applied the procedure to well water, seawater, tap water, river water, hospital wastewater, wastewater from an electrical power plant, and wastewater from an MDF factory. Samples were passed through 0.45-micrometer membrane filters to remove suspended particles before extraction. Cadmium in the examined well-water and tap-water samples was below the method’s detection limit. Because a certified reference material was unavailable, the team evaluated accuracy by adding known cadmium concentrations to the different sample types. Relative recoveries ranged from 95.2 to 97.9 percent, indicating that the varied chemical matrices had limited influence under the tested conditions. The findings do not establish that the material removes cadmium from contaminated water at treatment scale, nor do they demonstrate long-term performance in continuous systems. Instead, they show that a relatively simple nano-sorbent can prepare environmental samples for trace analysis using widely available FAAS equipment. The study reports the first experimental investigation of SBA-15 modified with CBIMMT for cadmium extraction and preconcentration, positioning the material as a candidate for routine monitoring where expensive plasma-based instruments may not be accessible.

The reported adsorption capacity should be interpreted as a laboratory equilibrium value rather than a direct prediction of how much cadmium the sorbent would remove from an untreated water stream. In an analytical extraction, the practical objective is quantitative and reproducible transfer of cadmium into the eluent. That makes selectivity, recovery, and consistency across different matrices as important as the capacity measurement itself. The study’s recovery tests, conducted by spiking several environmental and industrial water types, address this analytical requirement, although they do not substitute for testing against certified reference materials.

The material characterization also illustrates why several independent measurements are useful for a functionalized porous sorbent. Electron microscopy provides information about morphology and pore organization, surface-area analysis tracks changes in accessible porosity, elemental measurements indicate incorporation of the carbon-, nitrogen-, and sulfur-containing ligand, and thermogravimetry estimates the organic fraction and its thermal behavior. Together, these observations support the interpretation that CBIMMT was attached to, or associated with, the silica framework rather than the observed cadmium response arising solely from unmodified SBA-15. Further work could clarify attachment stability, regeneration over more cycles, and performance with more complex or continuously flowing samples.

Subject of Research: CBIMMT-functionalized SBA-15 for cadmium preconcentration and detection in water

Article Title: Synthesis of CBIMMT-modified SBA-15 as a novel nano-sorbent to preconcentrate, extraction and determination of trace amounts of Cd (II) ions in wastewater and natural water samples

Article References: Kazemi, F., Khodabakhshi-Omran, A., & Mirabi, A. (2026). Synthesis of CBIMMT-modified SBA-15 as a novel nano-sorbent to preconcentrate, extraction and determination of trace amounts of Cd (II) ions in wastewater and natural water samples. Journal of Saudi Chemical Society, 30(5), Article 64. https://doi.org/10.1007/s44442-026-00117-2

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00117-2

Keywords: cadmium detection, SBA-15, nanochemistry, solid-phase extraction, water pollution, wastewater analysis, mesoporous silica, flame atomic absorption, Synthesis, CBIMMT-modified, novel, nano-sorbent