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    Development of a molecularly imprinted polymer on silanized graphene oxide for the detection of 17-estradiol in wastewater
    (Wiley, 2024) Mughal, Zaib un Nisa; Aylaz, Gulgun; Shaikh, Huma; Memon, Shahabuddin; Andac, Muge
    This research article demonstrates the synthesis, characterization, and electrochemical evaluation of a molecularly imprinted polymer (MIP) on the surface of silanized graphene oxide (silanized GO), which is nanostructured and used to quantify 17-estradiol (E2) in wastewater. As characterization methods, X-ray diffraction (XRD), Raman spectroscopy, dynamic scattering light (DSL), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) were utilized to examine the synthesized GO, silanized GO, MIP-GO composite, and non-imprinted polymer (NIP)-GO (NIP-GO) composite. FTIR results confirmed the successful synthesis of GO composites. Raman study confirmed the synthesis of monolayer silanized GO, MIP-GO composite, and NIP-GO composite. Surface morphology revealed that after polymerization, the surface of silanized GO sheet-like morphology is covered with nanoparticles. Adsorption kinetics studies revealed that adsorption follows the pseudo-second-order kinetics. Further, we studied the performance of a MIP-GO-based sensor by optimizing the effects of pH, scan rate, and incubation period. The linear calibration was achieved between the oxidation peak current and E2 concentration from 0.1 to 0.81 ppm, with a detection limit of 0.037 ppm. The selectivity of the MIP-GO composite was also checked by using other estrogens, and it was found that E2 is 3.3, 0.5, and 1.4 times more selective than equilin, estriol, and estrone, respectively. The composite was successfully applied to the wastewater samples for the detection of E2, and a good percentage of recoveries were achieved. It suggests that the reported composite can be applied to real samples.Practitioner Points An innovative electrochemical sensor was developed for selective detection of 17-estradiol through molecularly imprinted polymer fabricated on the surface of silanized GO (MIP-GO composite). The developed method was comprehensively validated and found to be linear in the range of 0.1 to 0.8 ppm of 17-estradiol, with 0.037 ppm of limit of detection and 0.1 ppm of limit of quantification, respectively. The developed MIP-GO-composite-based electrochemical sensor was found 3.3, 0.5, and 1.4 times more selective for 17-estradiol than equiline, estriol, and estrone, respectively. The applicability of a developed sensor was also checked on wastewater samples, and a good percent recovery was obtained. A glassy carbon electrode (GCE) is modified with MIP-GO composite, and it binds E2 due to specific binding sites and is detected by voltammetric detection. Furthermore, by increasing the concentration of E2, the peak current intensity increases simultaneously. image
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    Effective Removal of the Direct Black-38 Dye from Wastewater Using a New Silica-Modified Resin: Equilibrium and Thermodynamics Modeling Studies
    (Amer Chemical Soc, 2020) Junejo, Ranjhan; Memon, Shahabuddin; Kaya, Savas
    In this study, the synthesis of p-diethanolaminomethylcalix[4]arene and its immobilization on a silica surface have been performed for the removal of the direct black (DB-38) dye from wastewater samples. The newly synthesized p-diethanolaminomethylcalix[4]arene-immobilized silica (DIS) resin has been analyzed and characterized by FTIR spectroscopy and SEM techniques. To check the efficiency of the DIS resin, batch and column adsorption procedures have been applied under the optimized parameters, i.e., resin dosage, pH, and temperature. To validate the experimental data, Langmuir, Freundlich, and D-R models have been applied. The results show that adsorption follows the Freundlich model well with a good correlation coefficient (R-2 = 0.999). Moreover, the energy E (kJ/mol) was calculated with the help of the D-R model, which suggested that the adsorption has an ion exchange nature. The DIS resin was also applied to real industrial samples of DB-38 dye wastewater. The results show that the DIS resin removes 99% of the dye successfully. Thermodynamics studies were conducted to know the feasibility and the mechanism of the adsorption reaction. The thermodynamic parameters show that the adsorption is spontaneous and exothermic. The theoretical calculation was performed at the B3LYP/DZP calculation level of the ADF program, and the power of the interaction between adsorbent and dye molecules can be determined in the light of chemical reactivity analysis.
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    Equilibrium, thermodynamic, and kinetic modeling studies for the adsorptive removal of oxyanions from water
    (TAYLOR & FRANCIS INC, DEC 2021) Elik, Mustafa; Junejo, Ranjhan; Jalbani, Nida Shams; Kaya, Savas; Serdaroglu, Goncagul; Memon, Shahabuddin
    Water is being contaminated by different oxyanions which have many negative effects on the human body. This study deals with the adsorptive removal of Cr2O7-2, AsO4-3, and ClO4-1 oxyanions from water using diethanolaminomethylcalix[4]arene bonded silica (DBS) resin. The capacity of DBS resin for the removal of oxyanions was checked through batch method under the optimized parameters such as pH, adsorbent dosage, concentration of oxyanions, and effect of temperature. The experimental data were analyzed through Langmuir, Freundlich, and Dubinin-Radushkevitch (D-R) adsorption isotherm models and the Langmuir model was the best fit model with a good correlation coefficient (R-2 0.998). The thermodynamic and kinetic studies were performed to check the mechanism and adsorption pathway of oxyanions onto DBS resin. The thermodynamic parameters such as (Delta H degrees, Delta S degrees, and Delta G degrees) describes that the adsorption of oxyanions was spontaneous and endothermic and followed by pseudo second order kinetic models very well. The reusability of resin was also checked and it has been observed that after 27 cycles only 2% loss in adsorption capacity. Moreover, the oxyanions were optimized at the B3LYP/LANL2DZ/6-311++G (d,p) level using G09W software to analyze the oxyanions-DBS interactions phenomenon.
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    Graphene oxide decorated with melamine-imprinted nanobeads for SERS detection of melamine in milk
    (Elsevier B.V., 2025) Nisa Mughal, Zaib un; Liman, Gorkem; Aylaz, Gulgun; Shaikh, Huma; Memon, Shahabuddin; Andac, Muge
    We present a novel, cost-effective SERS substrate for melamine detection in milk. Melamine is a nitrogen-rich compound illegally used to indicate high protein content. We developed a hybrid substrate based on molecularly imprinted polymer nanobeads functionalized with graphene oxide (MIP nanobeads@fGO). MIPs act as a door for selective detection and provide chemical enhancement. fGO achieves further chemical enhancement of the Raman signal by bond-making through functionalized moieties and electrostatic interaction with the ring moiety of fGO with melamine in SERS. Prior to polymerization, the molecular interaction between vinyl imidazole (VIM) as a functional monomer and melamine as a target molecule was modeled using AutoDockTools GUI (Graphical User Interface) and AutoGrid for molecular modelling simulations and grid calculations. From the clustering histogram, melamine and VIM molecules had the lowest binding energy of −0.77 kcal/mol. Also, the free energy of Melamine-VIM interaction at 298.15 K was −2729.21 kcal/mol, which is evidence that the interaction was energetically favorable. The fGO and MIP nanobeads@fGO were characterized by various techniques including FTIR and RAMAN spectroscopy, DSL and SEM. The SERS performance of MIP nanobeads@fGO was analyzed and showed excellent performance towards melamine with an EF of 1.3 × 106 and good reproducibility with an RSD of 8.3 %. A good correlation was observed between the –log concentration of melamine (μM) and the Raman intensity (a.u.) in a broad linear range from 7.9 E-5 μM to 7.9 E2 μM, with LOD and LOQ of 1.2 μM (0.15 ppm) and 3.6 μM (0.45 ppm), respectively. The USFDA and WHO introduced the tolerable level of melamine in milk and dairy products at no >2.5 ppm. Our LOD is below the tolerable limit, indicating that the MIP nanobeads@fGO substrate can be effectively used for food safety analysis in milk samples. © 2025