Preparation of the porphyrin-functionalized cotton fiber for the chromogenic detection and efficient adsorption of Cd 2+ ions

Synergistically active Fe3O4 magnetic and EDTA modified cellulose cotton fabric using chemical method and their effective pollutants removal ability from wastewater

A unique combination of cotton fabric (CF) with a mixture of EDTA and APTES Fe3O4 magnetic particles was developed and utilized for the first time as an adsorbent for removing pollutants from wastewater. Initially, Fe3O4 was synthesized using the co-precipitation method. Further, the surface of Fe3O4 was modified by introducing amino functional groups through a reaction with APTES, resulting in Fe3O4-NH2. Following this, the surface of carbon fiber (CF) was altered using ethylenediaminetetraacetic acid (EDTA) to create CF@EDTA. Through the use of EDC-HCl and NHS, Fe3O4-NH2 was attached to the surface of CF@EDTA, resulting in the final product CF@EDTA/Fe3O4. Subsequently, the prepared CF@EDTA/Fe3O4 was utilized to adsorb metal pollutants from wastewater, with a thorough analysis conducted using various characterization techniques including FTIR, SEM, EDX, XRD, VSM, and XPS to study the materials. The study specifically aimed to assess the adsorption performance of our cotton-based material towards As(III) and Cr3+ metal ions. The pH study was also performed. Results indicated that the material exhibited an adsorption capacity of approximately 714 mg/g for As(III) ions and 708 mg/g for Cr3+ ions. The Langmuir and Freundlich models, as well as pseudo-first and second-order models were also analyzed. The Langmuir and pseudo-second-order models were found to best fit the data. In terms of regeneration and reusability, the materials showed straightforward regeneration and recyclability for up to 15 cycles. The remarkable adsorption capacity, combined with the unique blend of cotton and Fe3O4 magnet, along with its recyclability, positions our material CF@EDTA/Fe3O4 as a promising contender for wastewater treatment and other significant areas in water research.

Synthesis of cellulose cotton-based UiO-66 MOFs for the removal of rhodamine B and Pb(II) metal ions from contaminated wastewater

The presence of pollutants in drinking water has become a significant concern recently. Various substances, including activated carbon, membranes, biochar, etc., are used to remove these pollutants. In the present study, a new composite comprising cotton fabric and a mixture of Metal-Organic Frameworks (MOFs) was synthesized and used as an adsorbent for eliminating pollutants from wastewater. At first, the UiO-66 MOFs were prepared by a simple method of reacting Zirconium (IV) chloride (ZrCl4) and p-Phthalic acid (PTA) after successful preparation of UiO-66 then modified its surface with amino functional groups by reacting with APTES to obtain UiO-66-NH2. Moreover, the cellulose cotton fabric (CF) surface was modified with Polydopamine (PDA) and obtained CF@PDA. Further, with the help of EDC-HCl and NHS, the UiO-66-NH2 grafted on the surface of the CF@PDA and finally obtained CF@PDA/UiO-66-NH2. In addition, the adsorption study was performed toward RhB dye and Pb(II) metal ion pollutants. The maximum adsorption toward RhB dye was 68.5 mg/g, while toward Pb(II) metal ions was 65 mg/g. In addition, the kinetic study was also conducted and the result favoured the Pseudo-second order kinetic study. The adsorption isotherm was also studied and the Langmuir model was more fitted as compared with the Freundlich model. Moreover, the material has excellent regeneration and recycling ability after ten cycles. The significant adsorption ability, the novel combination of cotton and MOFs, and the recycling feature make our material CF@PDA/UiO-66-NH2 a promising potential absorbent material for wastewater treatment and even in other important areas of water research.

Fabrication of reusable probe impregnated polymer monolithic sensor for the visual detection of Cd2+ in natural waters and cigarette samples

This work demonstrates the fabrication of a simple, low-cost naked-eye colorimetric solid-state sensor model for selective sensing of Cd2+. The sensor was developed using a polymer monolithic architect; namely, poly(n-allylthiourea-co-ethyleneglycol dimethacrylate) (poly(ATU-co-EGD) imbued with the chromophoric probe, 3-(quinoline-8-yldiazenyl)quinoline-2,4-diol (QYQD). The concocted indigenous perforated structural assemblies were studied through various microscopic, spectroscopic, and diffraction techniques. The template possessed a uniform arrangement of interconnected macro/mesoporous networks available for the maximum hooking of the QYQD probe moieties for the rapid and enhanced Cd2+ sensing process. The developed sensor offered an enhanced solid-state color transition response from yellow to dark meron for a proportional concentration increase of Cd2+ exhibiting precise absorption spectra with λmax at 475 nm. The relative stoichiometric binding ratio of the QYQD probe with Cd2+ was observed to be 2:1. The enhanced working conditions of the developed poly(ATU-co-EGD)QYQD sensor were tuned by validating various analytical conditions. The sensor exhibited a linear response signal from 2 to 150 ppb of Cd2+, and the corresponding LOD and LOQ values were 0.31 and 1.03 ppb, respectively. The efficacious performance drive of the sensor was validated in real water and cigarette samples that showed excellent data accuracy with a recovery value of ≥ 99.72% (n = 3).

A Comparison of a Conventional Chemical Coagulant and a Natural Coagulant Derived from Cassia fistula Seeds for the Removal of Heavy Metal Ions

Cassia fistula seed-derived coagulant has been reported to exhibit high coagulating-flocculating activity, environmental friendliness, and cost-effectiveness for the wastewater treatment, especially of textile wastewater. For heavy metal removal, however, research focusing on evaluating the feasibility of this material is still limited. Therefore, this study reports jar-test experiments in which the Zn2+ and Ni2+ removal efficiency of C. fistula coagulant was assessed. Moreover, a comparison of coagulation performance using a conventional chemical coagulant and the natural coagulant was performed. Characterization of the C. fistula seed-derived coagulant revealed the presence of important functional groups and fibrous networks with rough surfaces. A bench-scale study indicated that the coagulation performance of the two coagulants depends strongly on the initial concentration of metal ions, pH level, and coagulant dosage. The C. fistula seed-derived coagulant was found to possess higher removal efficiency than polyaluminum chloride. This natural coagulant removed over 80% of metal ions at the optimal conditions of pH 5.0, a metal ion concentration of 25 ppm, and a dosage of 0.8 and 1.6 g/L for Zn2+ and Ni2+, respectively. This study shows that C. fistula seed-derived coagulant is a potential alternative to chemical coagulants and could be developed to provide an environmentally friendly, economical, and efficient wastewater treatment.

Monitoring Cd2+ in oily wastewater using an aptamer-graphene field-effect transistor with a selective wetting surface

The discharge of oily industrial wastewater containing heavy metal ions with the development of industry severely threatens the environment and human health. Therefore, it is of great significance to monitor the concentration of heavy metal ions in oily wastewater quickly and effectively. Here, an integrated Cd²⁺ monitoring system consisting of an aptamer-graphene field-effect transistor (A-GFET), oleophobic/hydrophilic surface and monitoring-alarm circuits was presented for monitoring the Cd²⁺ concentration in oily wastewater. In the system, oil and other impurities in wastewater are isolated by an oleophobic/hydrophilic membrane before detection. The concentration of Cd²⁺ is then detected by a graphene field-effect transistor with a Cd²⁺ aptamer modifying the graphene channel. Finally, the detected signal is collected and processed by signal processing circuits to judge whether the Cd²⁺ concentration exceeds the standard. Experimental results demonstrated that the separation efficiency of the oleophobic/hydrophilic membrane to an oil/water mixture was up to 99.9%, exhibiting a high oil/water separation ability. The A-GFET detecting platform could respond to changes in the Cd²⁺ concentration within 10 min with a limit of detection (LOD) of 0.125 pM. The sensitivity of this detection platform to Cd²⁺ near 1 nM was 7.643 × 10^-2 nM^-1. Compared with control ions (Cr³⁺, Pb²⁺, Mg²⁺, Fe³⁺), this detection platform exhibited a high specificity to Cd²⁺. Moreover, the system could send out a photoacoustic alarm signal when the Cd²⁺ concentration in the monitoring solution exceeds the preset value. Therefore, the system is practical for monitoring the concentration of heavy metal ions in oily wastewater.

Synthesis of a New Co Metal-Organic Framework Assembled from 5,10,15,20-Tetrakis((pyridin-4-yl) phenyl)porphyrin "Co-MTPhPyP" and Its Application to the Removal of Heavy Metal Ions

The synthesis of a Co metal-organic framework assembled from 5,10,15,20-tetrakis((pyridin-4-yl)phenyl)porphyrin; TPhPyP) "Co-MTPhPyP" is reported. The TPhPyP ligand was synthesized via aldehyde condensation in 28% yield and characterized by ¹H nuclear magnetic resonance (¹H NMR), Fourier-transform infrared (FTIR), high-resolution mass spectrometry (HRMS), and UV-visible spectroscopy (UV-vis). Co-MTPhPyP was prepared by the solvothermal method from TPhPyP and CoCl₂·H₂O in 55% yield and characterized by X-ray powder diffraction (XRD), FTIR, thermogravimetric analysis (TGA), field-emission scanning electron microscopy with energy-dispersive X-ray (FESEM-EDS), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS), showing a particle size distribution of 418 ± 58 nm. The sorption properties of the Co-MTPhPyP for the effective removal of Pb(II) and Cu(II) were evaluated in an aqueous medium and Cthe results showed uptake capacities of 383.4 and 168 mg of the metal g^-1 after 2 h, respectively. Kinetic studies of Pb(II) adsorption by Co-MTPhPyP were adjusted to the pseudo-second-order model with a maximum adsorption capacity of 458.8 mg g^-1 at 30 min of exposition.

FeOOH nanosheet assisted metal ion coordination with porphyrins for rapid detection and removal of cadmium ions in water

Excessive cadmium ions in water bodies pose a severe challenge to ecology and human health, and the development of cadmium metal ion sensors is imperative. Here, we showed a dual-signal sensor based on colorimetry and fluorescence that was self-assembled from FeOOH nanosheets and TMPyP4. This nanocomposite enabled quick, selective cadmium ion detection. The Soret band at 442 nm in the UV absorption spectrum represented the coordination of cadmium ions with FeOOH@TMPyP4, and the absorbance increased linearly with increasing cadmium ion concentration (R² = 0.989 and linear range: 0.5-10 μM). In the presence of FeOOH nanosheets, the coordination of cadmium ions with FeOOH@TMPyP4 took only 70 min, and the detection limit of cadmium ions was as low as 0.24 μM. In addition, Cd²⁺ could be effectively removed from the nanocomposite due to its easy separation from water. This research developed a simple and efficient approach for detecting and removing heavy metal ions from water bodies.

Polymer brush-grafted cotton fiber for the efficient removal of aromatic halogenated disinfection by-products in drinking water

Apart from the activated carbon, other functional adsorbents are usually not frequently reported for the removal of disinfection by-products (DBPs) in drinking water. In this study, a novel polymer brush-grafted cotton fiber was prepared and for the first time used as adsorbents for the efficient removal of aromatic halogenated DBPs in drinking water in the column adsorption mode. Poly (glycidyl methacrylate) (PGMA) was grafted onto the surface of cotton fibers via UV irradiation, and then diethylenetriamine was immobilized on the PGMA polymer brush through amination reaction to obtain the aminated cotton fibers (ACFs). The adsorption performance of the prepared ACF was investigated with eight aromatic halogenated DBPs via dynamic adsorption experiments. The results revealed that ACF showed significantly longer breakthrough point (38,500-225,500 BV) for aromatic halogenated DBPs compared with the granular activated carbon (150-500 BV). Thomas model was used to fit the breakthrough curves, and the theoretical value of the maximum adsorption capacity ranged from 14.76 to 89.47 mg/g. The enhanced adsorption performance of the ACF for aromatic halogenated DBPs was mainly due to the formation of hydrogen bonds. Additionally, the partially protonated amine groups also improved the adsorption performance. Furthermore, the ACF also showed remarkable stability and reusability.

Highly efficient capture of uranium from seawater by layered double hydroxide composite with benzamidoxime

Through swelling/restoration reaction, benzamidoxime (BAO) is introduced into MgAl-LDH interlayers to assemble a new composite of MgAl-BAO-LDH (abbr. BAO-LDH). Wet samples of the BAO-LDH obtained by washing with diverse solvents are present in colloidal state, which facilitates the fabrication of thin film adsorbents convenient for actual application. After drying, the assembled sample exhibits floral morphology composed of thin nanosheets, much different from hexagonal morphology of NO₃^- intercalated MgAl-LDH precursor (NO₃-LDH), demonstrating a phenomenon rarely found in swelling/restoration. The BAO-LDH depicts an extremely large maximum sorption capacity (q_m^U) of 327 mg·g^-1 and ultra-high selectivity for U. At low U concentrations (5-10 ppm), nearly complete capture (~100%) is achieved in a wide pH range of 3-11, while at high U concentrations (110 ppm), quite high U removals (≥93.0%) are obtained at pH = 6-8, meaning perfect suitability for trapping U from seawater. For natural seawater containing trace amounts of U (3.93 ppb) coexisting with high concentration of competitive ions, the BAO-LDH displays significantly high U removal (87%). Complexation between interlayer BAO (N and O as ligands) with UO₂²⁺ and synergistic interactions of LDH layer hydroxyls with UO₂²⁺ contribute to the highly effective uranium capture. All results demonstrate the BAO-LDH is a promising adsorbent applied in seawater uranium extraction and nuclear wastewater disposal.

Bioimmobilization of lead by Bacillus subtilis X3 biomass isolated from lead mine soil under promotion of multiple adsorption mechanisms

In this study, a lead-resistant bacterium, Bacillus subtilis X3, was used to prepare a lead bioadsorbent for immobilization and removal of lead in lead solution. The lead shot precipitate was analysed by scanning electron microscopy combined with energy dispersive X-ray fluorescence microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The adsorbed lead was mainly mineralized to form Pb₅(PO₄)₃OH, Pb₁₀(PO₄)₆(OH)₂ and Pb₅(PO₄)₃Cl; however, other mechanisms that can also promote the mineralization of lead should not be ignored. For example, Na⁺ and Ca²⁺ on the cell wall surface were exchanged with Pb²⁺ in solution, which confirmed that the ion-exchange process occurred before mineralization. Moreover, adsorption bridging caused by extracellular polymeric substances also accelerated the further aggregation of lead, and the biomass was encapsulated by lead gradually. Hydroxyl, carbonyl, carboxyl and amine groups were not observed in lead mineral crystals, but the complexation between lead and these groups still benefited the mineralization of lead. The valence of Pb(II) was not changed after mineralization, which indicated that the biosorption process was not a redox reaction. Finally, biosorption occurred on the outer surface of the cell, but its specific surface area was relatively small, limiting the amount and efficiency of biosorption.

Efficient removal of Cd2+ and Pb2+ from aqueous solution with amino- and thiol-functionalized activated carbon: Isotherm and kinetics modeling

In order to address the increasingly severe pollution issue caused by heavy metals, activated carbon-based absorbents have gained considerable attention. Herein, two novel adsorbents, amino-functionalized activated carbon (N-AC) and thiol-functionalized activated carbon (S-AC), were successfully synthesized by stepwise modification with tetraethylenepentamine (TEPA), cyanuric chloride (CC) and sodium sulfide. The pristine and synthesized materials were characterized by BET analysis, SEM, FTIR spectroscopy, elemental analysis and zeta-potential analyzer. Meanwhile, their adsorption properties for Cd²⁺ and Pb²⁺ and the effects of various variables on the adsorption processes were systematically investigated. The findings confirmed that amino-groups and thiol-groups endowed the AC with a strong affinity for metal ions and that the pH of solution affected the uptake efficiencies of the adsorbents by influencing their surface charges. Furthermore, six isotherm models (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Sips and Redlich-Peterson) and four kinetic models (pseudo-first-order, pseudo-second-order, Intra-particle diffusion and Elovich) were applied to interpret the adsorption process at three different temperatures (288 K, 298 K and 308 K). The results indicated that temperature played an important role and that the rate-limiting step was chemosorption. A better fit for all adsorption systems was obtained with Langmuir model, with the maximum adsorption capacities at 298 K of 79.20 mg Cd²⁺/g and 142.03 mg Pb²⁺/g for N-AC, 130.05 mg Cd²⁺/g and 232.02 mg Pb²⁺/g for S-AC, respectively. Subsequently, the thermodynamic parameters revealed the nature of the adsorption was endothermic and spontaneous under the experimental condition. The possible adsorption procedures and the underlying mechanisms comprising physical and chemical interactions were proposed. Moreover, the as-synthesized adsorbents exhibited excellent regeneration performance after five adsorption/desorption cycles. The overall results demonstrated that both N-AC and S-AC could be the promising efficient candidates for removing Cd²⁺ and Pb²⁺ from contaminated water.

Sandwich-like Nanosystem for Simultaneous Removal of Cr(VI) and Cd(II) from Water and Soil

In this work, a novel nanosystem with a sandwich-like structure was synthesized via face-to-face combination of two pieces of waste cotton fabrics (CFs) carrying ferrous sulfide (FeS) and carboxyl-functionalized ferroferric oxide microsphere (CFFM), respectively, and the obtained nanosystem was named as FeS/CFFM/CF. Therein, FeS has high reduction and adsorption capabilities for hexavalent chromium (Cr(VI)), CFFM possesses a high adsorption ability on cadmium ion (Cd(II)) through electrostatic attraction and chelation, and CF displays high immobilization ability for FeS and CFFM and adsorption performance on Cd(II). FeS/CFFM/CF could simultaneously remove Cr(VI) and Cd(II) from water and inhibit the uptake of Cr and Cd by fish and water spinach, ensuring the food safety. Besides, this technology could efficiently control the migration of Cr(VI) and Cd(II) in the sand-soil mixture, which was favorable to prevent their wide diffusion. Importantly, FeS/CFFM/CF possessed a high flexibility and could be conveniently produced with needed scale and shape and easily separated from water and soil, displaying a promising approach to remediate Cr(VI)-/Cd(II)-contaminated water and soil and a huge application potential.

Sulfonylcalix[4]arene functionalized nanofiber membranes for effective removal and selective fluorescence recognition of terbium(iii) ions

A novel sulfonylcalix[4]arene functionalized aminated polyacrylonitrile (APAN) nanofiber membrane was fabricated, exhibiting good Tb³⁺ adsorption capacity and photoluminescence performance.

Kinetic, isotherm and thermodynamic studies with linear and non-linear fitting for cadmium(II) removal by black carbon of pine cone

In this study, black carbon from pine cone (BCPC) and acidic-modified BCPC (MBCPC) powder as a popular agricultural waste in the southeast of Iran were used for cadmium removal from aqueous solutions. The effect of various factors, such as surface chemistry and dosage of adsorbent, contact time, size of particles, initial concentration of cadmium, temperature, and pH of aqueous solutions, was investigated. The results show cadmium removal with usage of the mentioned adsorbents increased after acidic modification. It was noteworthy in this work that the removal percentage of pollutant was above 90% for suggested biosorbents. The obtained experimental data for optimum conditions were selected to model the adsorption behavior of the materials with usage of six isotherm equations via non-linear fitting method and the residual root mean square error estimation for each model. The adsorption of cadmium preferably fitted Khan and Langmuir-Freundlich isotherms for BCPC and MBCPC adsorbents, respectively. The kinetic studies via linear fitting method proved the second-order kinetic was the applicable model for the adsorption process. Thermodynamic studies show the adsorption process of cadmium onto BCPC and MBCPC was spontaneous and endothermic.

Analysis on the Composition/structure and Lacquering Techniques of the Coffin of Emperor Qianlong Excavated from the Eastern Imperial Tombs

This article presents the results of an investigation on the coffin of Emperor Qianlong excavated from the Eastern Imperial Tombs of the Qing Dynasty in Zunhua, China. The composition, structure and lacquering techniques used in the manufacturing process were analyzed in this project. Stereoscopic Microscopy, SEM-EDS, XRD, FTIR, Raman, Double-shot Py-GC/MS were used as scientific analytical methods. The results show that the structure of the coffin body consists of a wooden body layer, a lacquer ash layer and a lacquer film pigment layer. The lacquer ash layer consists of nine stucco layers and ten fiber layers on top of each other in an alternating order. The lacquer film pigment layer consists of mineral pigments, lacquer sap, animal gelatin, drying oil, quartz sand and proteinaceous materials. Pigments used in the lacquer film include calcite white, carbon black, cinnabar red and gold. The presence of three distinctive catechols along with the other catechols’ and phenols’ profiles in the lacquer film matrix clearly indicate the species of the lacquer tree was Rhus. Vernicifera. Several distinctive lacquering techniques that improved the coffin body’s stability and mechanical strength were identified in the investigation, including the “wan lacquering”, “painting lacquer above the gold” and “Jin Jiao”.

A selective distance-based paper analytical device for copper(II) determination using a porphyrin derivative

Meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin sulfonate (TDMPzP), a water-soluble porphyrin derivative, was synthesized and used as a colorimetric reagent for Cu²⁺ detection on a microfluidic paper-based analytical device (µPAD) using distance-based quantification. TDMPzP showed a high selectivity for Cu²⁺ detection in aqueous solutions. When Cu²⁺ was added to the TDMPzP under acidic conditions, a color change from green to a pink was observed by the naked eye. Under optimized conditions, the application of this system to a distance-based μPAD exhibited good analytical response. The presence of common metal ions (Al³⁺, Fe³⁺, Mg²⁺, Co²⁺, Mn²⁺, Zn²⁺, Pb²⁺, Cd²⁺, Sn²⁺, and Ni²⁺) did not interfere with Cu²⁺ detection within reasonable tolerance ratios. The lowest concentration of copper that could be measured was 1mgL^-1 (1ppm) which meets the requirements for drinking water contamination regulations from the US Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines for drinking water. Real drinking water samples were analyzed to confirm the practical application of this system and the results showed good agreement with ICP-MS data. This distance-based µPAD based on TDMPzP for Cu²⁺ detection is convenient and effective for real-time drinking water analysis.

Hg selective adsorption on polypropylene-based hollow fiber grafted with polyacrylamide

A novel polypropylene hollow fiber membrane with a new function of selective adsorption of mercury ions in aqueous solutions was successfully prepared. The surface of the polypropylene hollow fiber membrane was initially modified with polydopamine by surface polymerization, and subsequently grafted with polyacrylamide (PAM) polymer brush via the surface initiated atom transfer radical polymerization (SI-ATRP) technique (thereafter named as PP-PAM). This study investigated the adsorption performance of Hg(II) ions by PP-PAM and the effect of various influencing factors on Hg(II) ion adsorption. The experiment indicated that the Hg(II) adsorption capacity of the PP-PAM increased with the increase of the pH, and the Hg(II) adsorption kinetics was consistent with the pseudo-second-order kinetic model. The adsorption isotherm followed the Langmuir model, with the maximum adsorption capacity calculated to be 0.854 mmol/g for Hg(II) ions. The adsorption study in multi-component system indicated that PP-PAM preferentially adsorbs Hg(II) over Pb(II) ions, with significant adsorption capacity difference of the two heavy metal ions. This study provided an efficient method for the preparation of the adsorptive polypropylene hollow fiber membrane, which expands its application for the selective removal of heavy metal ions.

Scientific investigation of the lacquered wooden coffin of Xiang Fei excavated from Eastern Royal Tombs of the Qing Dynasty

The composition, structure, and lacquering craft used to manufacture the coffin of Xiang Fei were analyzed using multiple analytical methods.

Visible sequestration of Cu2+ions using amino-functionalized cotton fiber

In this study, an amino functionalized cotton fiber, which was used to adsorb Cu²⁺ionsviavisible sequestration, was prepared and investigated.