Neodymium-doped polyaniline supported Zn-Al layered double hydroxide (PANI@Nd-LDH) nanocomposite has been prepared via an ex-situ oxidative polymerization process. The as-prepared nanocomposite shows ...selective fluorescence detection and adsorption of hexavalent chromium Cr(VI) within a short period. The fluorescence intensity of PANI@Nd-LDH decreases linearly with Cr(VI) concentrations ranging from 200 ppb to 1000 ppb with a limit of detection (LOD) of 1.5 nM and a limit of quantification (LOQ) of 96 nM. The sensing mechanism can be ascribed by the inner filter effect of Cr(VI), the intercalation of Cr(VI) within the intergallery region of LDH, and the synergistic affinity of metal ions along with the polymer chain for Cr(VI). The adsorption performance of PANI@Nd-LDH nanocomposite is evaluated for Cr(VI) from wastewaters, which displayed high removal capacity towards Cr(VI) (219 mg/g) as compared on bare Nd-LDH (123 mg/g) and LDH (88 mg/g) respectively. The adsorption of Cr(VI) on PANI@Nd-LDH depends on the pH of the aqueous solution. The adsorption isotherm and kinetics are supported by the Langmuir model and pseudo-second-order model, respectively. Owing to the highly sensitive detection and adsorption of Cr(VI) from aqueous water samples demonstrated the potential application of PANI@Nd-LDH as an excellent environmental probe can be exploited.
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•PANI@Nd-LDH was synthesized and employed for selective detection and removal of Cr(VI) in water.•PANI@Nd-LDH shows excellent sensitivity for the detection of Cr(VI) at ppb level.•The high adsorption capacity for Cr(VI) (219 mg/g) is attributed to complexation and ionic interactions.•The detection of Cr(VI) is based on inner filter effect and ionic interactions.•PANI@Nd-LDH could possibly emerge as an excellent adsorbent as well as sensor for the removal of Cr(VI) from wastewater.
Transition metal–doped carbon-coated layered double hydroxides for the removal of lead (II) and hazardous organic dyes have attracted increasing attention for wastewater treatment in recent years. In ...this work, nanostructured CoBi-LDH/Cr@CNT composites were successfully synthesized by hydrothermal route. The CoBi-LDH/Cr@CNT was characterized by instrumental techniques such as XRD, FTIR, TEM, SEM, XPS and TGA/DTA. Adsorption of Pb2+ and organic dyes, i.e.,Rose Bengal (RB) and Congo red (CR) by CoBi-LDH/Cr@CNT was performed by batch experiment.The effect of several parameters including contact time, adsorbent dose, pH, temperature, and concentration was also investigated. Under optimum conditions, the adsorption capacity of CoBi-LDH/Cr@CNT for RB, CR and Pb2+ pollutants were (278.4 mg g−1), (164.6 mg g−1) and (503.2 mg g−1) and the removal efficiency achieved is 98.2%, 95.0% and 100% respectively. The selectivity of CoBi-LDH/Cr@CNT nanocomposite towards Pb2+ has been studied using ICP-AES.The isothermal results were analyzed using Freundlich and Langmuir models. Adsorption isotherm for Pb2+(R2 = 0.975), RB (R2 = 0.997) and CR (R2 = 0.992) agrees with the Langmuir model indicating monolayer adsorption. The sorption kinetics data well fitted pseudo-first-order model for Pb2+ (R2 = 0.975), RB (R2 = 0.996), and CR (R2 = 0.995).The results demonstrated that the synthesized CoBi-LDH/Cr@CNT nanocomposite can be used as an effective sorbent for the removal of pollutants from wastewater.
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•CoBi-LDH/Cr@CNT was employed for selective adsorption of Pb(II) and hazardous dyes.•The high adsorption capacity for Pb(II) (503.2 mg g−1) is attributed to electrostatic interactions.•The maximum adsorption capacity for RB and CR dyes are (278.4 mg g−1) & (164.6 mg g−1).•CoBi-LDH/Cr@CNT could possibly emerge as an excellent adsorbent for the wastewater treatment.
Here, the hybrid material of polyaniline/layered double hydroxide@carbonnanotubes (PANI/LDH@CNT) is considered a multifunctional material. Instrumental methods, including FTIR, XRD, TEM, SEM, and ...TGA/DTA were utilized to characterize PANI/LDH@CNT. The polymerization method created PANI/LDH@CNT as an adsorbent to remove toxic iodine in hexane solution with a capture capacity of 303.20 mg g−1 during 9 h. It is 900 mg g−1 in the vapor phase within 24 h. After three cycles, the PANI/LDH@CNT could be regenerated while maintaining 91.90 % iodine adsorption efficiency. Due to the presence of free amine (-N) groups, OH−, CO2H, and π-π conjugated structures in the PANI/LDH@CNT, it is also explored for efficient iodine uptake. It was demonstrated that the pseudo-first-order (PFO) and Langmuir model had the optimum correlation with the kinetic and isotherm data, respectively. Moreover, the use of PANI/LDH@CNT is not only limited to iodine capture; it can also be utilized as a sensitive sensor that displays a fluorescence “turn-off” response for Mn7+ and Cr6+ ions and a fluorescence “turn-on” response in the case of Al3+ ions. The fluorescence intensity of the PANI/LDH@CNT was turned off in the presence of Mn7+ and Cr6+ because of the fluorescence inner filter effect (IFE) mechanism. In contrast, the fluorescence intensity was turned on in the case of Al3+, relying on the chelation-enhanced fluorescence (CHEF) effect mechanism. Under optimal conditions, the limit of detection (LOD) of 51, 59, and 81 nM for Mn7+, Cr6+, and Al3+, respectively. According to the literature, this is probably the first example based on PANI/LDH@CNT as a multifunctional hybrid material employed as an adsorbent for capturing radioactive iodine and as a chemosensor for detecting heavy metal ions in aqueous solutions.
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•Ex-situ oxidative polymerization was used to synthesize PANI/LDH@CNT.•The adsorption capacity for I2(aq) was 303.20 mg g−1 and 900 mg g−1 in I2(vap).•PANI/LDH@CNT showed a high sensitivity for heavy metal ions detection at ppb levels.
The toxicity of clean fresh water has become a major concern in the 21st century. The pollution of fresh and marine water bodies via anthropogenic activities introduces fatal chemicals like heavy ...metal ions into the environment causing disastrous impacts on human life as well as floral-faunal biota. Hence, it is crucial to develop a nanomaterial that can probe on these lethal heavy metal ions feasibly as well as with low detection limits. Metal-Organic Frameworks are frequently employed in optics as fluorescence sensors for detecting heavy metal ions. Therefore, in this study, Ni(II) was doped into the UiO-66 network, and the fluorescent characteristics of the obtained MOF structure were observed. The morphological characterizations were conducted via PXRD and SEM while the optical tests based on fluorescent spectroscopy were given more attention. The as synthesized MOF i.e., Ni@UiO-66 gave excellent fluorescent detection exhibiting “Turn-Off” for Hg(II) and Fe(III), while “Turn On” for Cr(VI), and Al(III) analytes. In aqueous phase, the lowest detection limit values of 7.98 x 10−7 M for Hg(II) ions is observed. The former's sensing mechanism was attributed to the inner filter effect (IFE), while the latter's mechanism could potentially be linked to the chelation-enhanced fluorescent (CHEF) effect. These findings imply that the Ni@UiO-66 metal-organic framework has the potential to be used for the detection for minute quantities of Hg(II), Al(III), Cr(VI), and Fe(III) ions.
•Ni@UiO-66 was synthesized via a solvothermal process by economical methods.•Ni@UiO-66 shows excellent sensitivity for the detection of heavy metal ions.•Hg(II) and Fe(III) are detected based on the inner filter effect (IFE).•The Ni@UiO-66 shows a chelation-enhanced fluorescence effect (CHEF) in the presence of Cr(VI), and Al(III).
Neodymium-doped Zn–Al layered double hydroxide (Nd/Zn-Al LDH) with excellent photocatalytic activity was prepared by a one-step hydrothermal method. The morphology and physicochemical properties of ...as-synthesized photocatalysts were well analyzed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL), UV-diffuse reflectance spectroscopy (UV-DRS), and Brunauer-Emmett-Teller (BET) surface analysis. Doping Nd3+ into Zn–Al LDH enhances the overall catalytic activity of the nanocomposite, like better electron–hole pair separation, increase in interplanar distance, fast electron transfer, and large surface area. The as-prepared nanocomposite shows excellent degradation of three different dyes under visible light irradiation. The degradation efficiency of these dyes follows the order of Congo red > rose Bengal > fast green. Furthermore, liquid chromatography-mass spectrometry (LC-MS) was employed to propose a possible photocatalytic degradation pathway for Congo Red and Rose Bengal dyes by Nd/Zn–Al LDH. With the help of radical trapping experiments, it is revealed that during the photoexcitation process, the primary reactive intermediates are hydroxyl radicals.
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Herein, Nd(NO3)3(H2pzdca) n (MA-1) was synthesized from a reaction of 2,3-pyrazinedicarboxylic acid H2Pzdca as an organic linker with salt of Nd(III) under solvothermal conditions. The detailed ...structural analysis for crystals was performed utilizing single-crystal X-ray diffraction (SCXRD). After that, the neodymium-based coordination polymer (MA-1) crystal was directly generated upon the surface of functionalized carbon nanotubes (F-CNTs) through bonds or affinity between F-CNTs and MA-1 via the solvothermal approach. Meanwhile, the existence of F-CNTs does not affect the production of MA-1 crystals. FT-IR, PXRD, SEM, TEM, and SCXRD studies were used to characterize the crystalline material, MA-1 and MA-1@CNT. To investigate the MA-1@CNT sensing properties, Pb(II), As(III), Cr(VI), and nitrobenzene (NB) were utilized as analytes. It is worth mentioning that MA-1@CNT developed as a susceptible sensor exhibits a fluorescence “turn-on” response for Pb(II) and As(III) ions, while a fluorescence “turn-off” response in the case of Cr(VI) and NB with significantly low limit of detection (LOD) values of 15.9 for Pb(II), 16.0 for As(III), 76.9 for Cr(VI), and 21.1 nM for NB, which are comparable with the lowest LOD available in the literature. Furthermore, MA-1@CNT could be conveniently regenerated and reused for at least three cycles by simply filtering and washing with water several times. The sensing mechanism is ascribed to the inner filter effect owing to the overlap between the emission and/or excitation bands of MA-1@CNT with the absorption bands of Cr(VI) and NB. In contrast, the fluorescence enhancement in the case of Pb(II) and As(III) could be correlated to the chelation-enhanced fluorescence phenomenon. These results indicate that MA-1@CNT is an ideal sensor for Pb(II), As(III), Cr(VI), and NB recognition.
A nano-hybrid metallic carbon-based architecture with fascinating new properties has been developed. MOs@CNT hybrid is designed using carbon nanotubes (CNTs) and metal oxides (MOs) by hydrothermal ...synthesis. FTIR, SEM, TEM, PXRD and TGA analysis were used to characterize MOs@CNT nanomaterial. MOs@CNT is employed for the adsorption of rose bengal (RB) showing excellent removal capacity (245.6 mg g−1) as compared to pristine MOs (48.8 mg g−1) at 298 K. Further the mechanism of dye adsorption is also proposed. Interestingly, this nanomaterial has a high sensing activity for nitroaromatic compounds (NACs) and chromium Cr(VI), where MOs@CNT 0.02g indicate a sensitive and selective luminescence quenching response to Cr(VI), nitrobenzene (NB), m-nitroaniline (m-NA) and p-nitroaniline (p-NA) in an aqueous medium with the average high quenching Ksv rate of 3.3 × 105 M−1 for NB and low detection limits up to 2.02 × 10−9 M also for NB. Therefore the new-fangled MOs@CNT emerges as a long-term multifunctional material for the detection of harmful NACs and Cr(VI) in an aqueous environment, moreover a great adsorbent for dyes.
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We have designed and synthesized new metal oxides loaded carbon nanotube with promising multifunctional importance. The MOs@CNT contains sensing properties of some nitroaromatic compounds and Cr(VI) with ultra-low detection limits along with selective adsorption ability for rose bengal. Such properties were observed in this type of compound for the first time therefore MOs@CNT being potential sustainable material for the desired functional applications in future attempts.
•Metal oxide/multi-walled carbon nanotubes (MOs@CNT) were synthesized through hydrothermal treatment with pyridine.•MOs@CNT shows excellent sensitivity for the detection of nitroaromatic compounds (NACs) and Cr(VI) ions at ppb levels.•The maximum adsorption capacity for Rose Bengal (RB) dye was found to be 245.6 mg/g.•The adsorption mechanism of MOs@CNT toward Rose Bengal (RB) dye is explored.
Herein, metal–organic framework (MOF)-based adsorbents are designed with distinct hard and soft metal building units, namely, Co2 ICoII(PD)2(BP) (Co_PD-BP) and Cu2 ICuII(PD)2(BP) (Cu_PD-BP), where ...H2PD = pyrazine-1,4-diide-2,3-dicarboxylic acid and BP = 4,4′-bipyridine. The designed MOFs were characterized via spectral and SCXRD techniques, which confirm the mixed-valent states (+1 and +2) of the metal ions. Topological analysis revealed the rare ths and gwg topologies for Co MOF, while Cu-MOF exhibits a unique 8T21 topology in the 8-c net (point symbol for net: {424·64}). Moreover, severe environmental issues can be resolved by effectively removing heterocyclic organosulfur compounds from fuels via adsorptive desulfurization. Further, the developed MOFs were investigated for sulfur removal via adsorptive desulfurization from a model fuel consisting of dibenzothiophene (DBT), benzothiophene (BT), and thiophene (T) in the liquid phase using n-octane as a solvent. The findings revealed that Cu_PD-BP effectively removes the DBT with a removal efficiency of 86% at 300 ppm and an operating temperature of 25 °C, with a recyclability of up to four cycles. The adsorption kinetic analysis showed that the pseudo-first-order model could fit better with the experimental data indicating the physisorption process. Further, the studies revealed that adsorption capacity increased with the increasing initial DBT concentration with a remarkable capacity of 70.5 mg/g, and the adsorption process was well described by the Langmuir isotherm. The plausible reason behind the enhanced removal efficiency shown by Cu_PD-BP as compared to Co_PD-BP could be the soft–soft interactions between soft sulfur and soft Cu metal centers. Interestingly, density functional theory (DFT) studies were done in order to predict the mechanism of binding of thiophenic compounds with Cu_PD-BP, which further ascertained that along with other interactions, the S···π and S···Cu interactions predominate, resulting in a high uptake of DBT as compared to others. In essence, Cu_PD-BP turns out to be a promising adsorbent in the field of fuel desulfurization for the benefit of mankind.
Herein, metal-organic framework (MOF)-based adsorbents are designed with distinct hard and soft metal building units, namely, Co
Co
(PD)
(BP) (
) and Cu
Cu
(PD)
(BP) (
), where H
PD = ...pyrazine-1,4-diide-2,3-dicarboxylic acid and BP = 4,4'-bipyridine. The designed MOFs were characterized via spectral and SCXRD techniques, which confirm the mixed-valent states (+1 and +2) of the metal ions. Topological analysis revealed the rare
and
topologies for Co MOF, while Cu-MOF exhibits a unique
topology in the 8-c net (point symbol for net: {4
·6
}). Moreover, severe environmental issues can be resolved by effectively removing heterocyclic organosulfur compounds from fuels via adsorptive desulfurization. Further, the developed MOFs were investigated for sulfur removal via adsorptive desulfurization from a model fuel consisting of dibenzothiophene (DBT), benzothiophene (BT), and thiophene (T) in the liquid phase using
-octane as a solvent. The findings revealed that
effectively removes the DBT with a removal efficiency of 86% at 300 ppm and an operating temperature of 25 °C, with a recyclability of up to four cycles. The adsorption kinetic analysis showed that the pseudo-first-order model could fit better with the experimental data indicating the physisorption process. Further, the studies revealed that adsorption capacity increased with the increasing initial DBT concentration with a remarkable capacity of 70.5 mg/g, and the adsorption process was well described by the Langmuir isotherm. The plausible reason behind the enhanced removal efficiency shown by
as compared to
could be the soft-soft interactions between soft sulfur and soft Cu metal centers. Interestingly, density functional theory (DFT) studies were done in order to predict the mechanism of binding of thiophenic compounds with
, which further ascertained that along with other interactions, the S···π and S···Cu interactions predominate, resulting in a high uptake of DBT as compared to others. In essence,
turns out to be a promising adsorbent in the field of fuel desulfurization for the benefit of mankind.
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•Tin silicomolybedate and chitosan-based hydrogel nanocomposite (CS-g-PA@TSM) for wastewater treatment.•CS-g-PA@TSM exhibited high selectivity for the removal of lead from synthetic ...and wastewaters.•The CS-g-PA@TSM shows enhanced efficiency for degradation of CIP and sensing of ammonia gas.•CS-g-PA@TSM nanocomposite can be effectively used as photocatalyst, sensor and adsorbent.
Tin-based ternary inorganic semiconductors enable new opportunities for the development of functional hydrogel nanocomposites to cope with environmental pollution. In this regard, we have synthesized highly functionalize CS-g-PA@TSM nanocomposites by the impregnation of Tin- Si/Mo (TSM) semiconductor in the matrix of chitosan/polyacrylamide (CS-g-PA) using the hydrothermal route. Multifunction platform showed ammonia vapor sensing, fluorescent detection as well as removal and exchange recovery of lead ions from wastewater and its photocatalytic behavior towards antibiotic degradation. The CS-g-PA@TSM nanocomposite achieved almost 96% photodegradation towards Ciprofloxacin (CIP) after 130 min of irradiation which was further monitored and confirmed by 3-D excitation-emission matrix fluorescence and GC–MS techniques, respectively. The photocatalytic mechanism of the CS-g-PA@TSM under visible light irradiation was clarified, which established the generation of O2− / OH species in the form of dominant radicals. The experimental results indicated that the improved photocatalytic performance of CS-g-PA@TSM could be attributed to enhance the optical absorption and efficient separation along with the migration of photoinduced charge carriers. The nanomaterial also exhibits significant Pb2+ recovery (95.6%) from wastewater with a limit of detection (LOD) and limit of quantification (LOQ) as 3.38 μg L−1 and 9.34 μg L−1, respectively. The CS-g-PA@TSM nanocomposite was successfully employed up to five regeneration cycles with 98% regeneration capacity. Thus, the finding of the present study establishes that the multifunctional CS-g-PA@TSM nanocomposite platform could be used for the treatment of antibiotics (CIP), ammonia, and Pb2+ from wastewater.
