Poly(vinyl alcohol) Embedded with Montmorillonite Clay and Nano Titania: A Scale-Up for Sustainable Environmental Remediation

Liu H., Chen Z., Lin X., Zhang X., Cai Y., Zhang Y., Sun B., Mei X., Lyu W., Kaner R.B., Zhu M., Liao Y.

Dehghani M.T., Delnavaz M.

AbstractThe rapid growth of industrialization has led to the uncontrolled pollution of the environment, and rapid action is needed. This study synthesized Ag/TiO2/polyvinyl alcohol (PVA) nano photocatalyst for promising light-derived photocatalytic removal of heavy metal ions. The design of experiment (DOE) was used to study the effect of important factors (pH, reaction time, and photocatalyst dosage) to maximize the final performance of the photocatalyst. In the optimized condition, the Ag/TiO2/PVA nano-photocatalyst removed more than 94% of Cr6+ in 180 min, and the efficiency was more than 70% for Cu2+, Zn2+, and Ni2+ metal ions. The adsorption of the heavy metal ions on the photocatalyst was described well with the Langmuir isotherm, while the pseudo-second-order linear kinetic model fitted with the experimental data. The nano-photocatalyst's stability was confirmed after maintaining its performance for five successive runs. The enhanced photocatalytic activity for the heavy metal ions removal can be attributed to the presence of metallic silver nanoparticles (electron transfer and plasmonic fields mechanisms) and PVA, which delayed the recombination of electron–hole. The synthesized ternary Ag/TiO2/PVA nano-photocatalyst showed promising performance for the elimination of heavy metal ions and can be used for environmental remediation purposes.

Yaseen M., Khan A., Humayun M., Bibi S., Farooq S., Bououdina M., Ahmad S.

El Jery A., Alawamleh H.S., Sami M.H., Abbas H.A., Sammen S.S., Ahsan A., Imteaz M.A., Shanableh A., Shafiquzzaman M., Osman H., Al-Ansari N.

AbstractThe treatment of methylene blue (MB) dye wastewater through the adsorption process has been a subject of extensive research. However, a comprehensive understanding of the thermodynamic aspects of dye solution adsorption is lacking. Previous studies have primarily focused on enhancing the adsorption capacity of methylene blue dye. This study aimed to develop an environmentally friendly and cost-effective method for treating methylene blue dye wastewater and to gain insights into the thermodynamics and kinetics of the adsorption process for optimization. An adsorbent with selective methylene blue dye adsorption capabilities was synthesized using rice straw as the precursor. Experimental studies were conducted to investigate the adsorption isotherms and models under various process conditions, aiming to bridge gaps in previous research and enhance the understanding of adsorption mechanisms. Several adsorption isotherm models, including Langmuir, Temkin, Freundlich, and Langmuir–Freundlich, were applied to theoretically describe the adsorption mechanism. Equilibrium thermodynamic results demonstrated that the calculated equilibrium adsorption capacity (qe) aligned well with the experimentally obtained data. These findings of the study provide valuable insights into the thermodynamics and kinetics of methylene blue dye adsorption, with potential applications beyond this specific dye type. The utilization of rice straw as an adsorbent material presents a novel and cost-effective approach for MB dye removal from wastewater.

Satheeshkumar K.V., Bindu M., Suresh S., Anil A., Sujoy S., Mohanan A., Periyat P.

Polymeric nanocomposite hydrogels were developed from a hydrophilic natural polymer, sodium alginate (SA) with black nano crystalline titania (black TiO2) by using ionic cross linker CaCl2, in view of the possible enhancement in properties of SA towards water treatment application. The optimum conditions for the preparation of films were done by varying the amount of cross-linking agent, cross-linking time and the amount of black nano crystalline TiO2. The nanocomposite hydrogels were then characterized by X-ray diffraction studies (XRD), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The surface morphologies of the nanocomposite have been examined by using scanning electron microscopy (SEM). The swelling studies and its kinetics have been investigated under diverse PH conditions. Permeability of the gels were assessed in terms of film characteristics and PH. The results proved that the gels exhibit PH sensitivity. Based on the results, we have proposed a possible mechanism of water transport through the gels. The developed SA/black TiO2 nanocomposite hydrogels have been successfully employed for the efficient degradation organic dyes such as methylene blue and malachite green. The experimental results of dye degradation studies have been compared with theoretical models and it has been observed that the dye degradation follows pseudo second order kinetics for both methylene blue and malachite green. By altering the PH, the nanocomposite hydrogels can be broken and spent TiO2 can be recovered.

Wawrzkiewicz M., Frynas S., Podkościelna B.

A new phosphorus-containing sorbent was prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) and trimethylvinyl silane (TMVS) with diphenylvinylphoshine oxide (DPVO). It was characterized and applied in the removal of cationic dyes such as C.I. Basic Yellow 2 (BY2), C.I. Basic Blue 3 (BB3) and C.I. Basic Red 46 (BR46) using the batch method. Spectroscopic analysis indicated that the phosphinoyl group was introduced into the sorbent structure. Equilibrium adsorption data were fitted to the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The Freundlich model is the most suitable to describe the adsorption of BB3 (the Freundlich constant kF = 32.3 mg1−1/nL1/n/g) and BY2 on the sorbent (13.8 mg1−1/nL1/n/g), while the Langmuir model is the most adequate to describe the adsorption of BR46 (the monolayer capacity Q0 = 2.7 mg/g). The kinetics of the dye adsorption follows the assumptions of the pseudo-second-order (the rate constants k2 = 0.087 ÷ 0.738 g/mg min) model rather than pseudo-first-order or intraparticle diffusion. The presence of Na2SO4 and cationic surfactant in the aqueous solutions inhibited dye retention by the DPVO–EGDMA–TMVS. Adsorbent regeneration efficiency does not exceed 60% using 1 M NaCl and 1 M HCl solutions in the presence of 50% v/v methanol.

Aradhya R., Sundara Rajan J.

AbstractThe effect of incorporation of micron sized aluminum trihydrate, multi‐walled carbon nanotubes, and graphene nano platelets into glass fiber reinforced epoxy matrix is investigated using dynamic mechanical analysis. The objective of the investigation was to develop polymer central core of high temperature low sag transmission conductor. The effect of individual and hybrid carbon fillers on the viscoelastic properties of the epoxy composites is investigated and discussed. The storage modulus of the glass reinforced epoxy increases by 20% at room temperature due to incorporation of carbon nanofillers. In glass transition region, the increase is higher between 40% and 60% and it varies up to 90% in the rubbery region. Key attributes of carbon filler addition are limited enhancement of storage modulus at room temperature, higher enhancement over glassy, glass transition, and rubbery regions. The carbon fillers extend the temperature range of the glassy region. The cross‐link density, filler efficiency, and degree of entanglement of fibers are estimated to understand the implications of the carbon fillers on the viscoelastic properties. The loss modulus peak of glass epoxy composite increases from 2800 to 3900 MPa with carbon fillers and the increase in glass transition temperature is 47°C. Incorporation of carbon fillers leads to increase of damping factor peak from 0.2 to 0.28. Cole–Cole plots have established the inherent heterogeneity of epoxy systems due to the presence of carbon fillers. Prediction models for storage modulus and damping factor have been proposed to highlight the influence of geometry and size of carbon filler.

Rafique M., Hajra S., Irshad M., Usman M., Imran M., Assiri M.A., Ashraf W.M.

Chen Z., Liu H., Lin X., Mei X., Lyu W., Liao Y.

A competitive proton-trapping strategy is proposed to endow anti-freezing organohydrogel fibers with unevenly distributed ion carriers and breakable proton-migration pathways for high-strain-sensitivity wearable sensors.

Pavel M., Anastasescu C., State R., Vasile A., Papa F., Balint I.

It is well-documented that large-scale pollution generated by human activity has a dramatic impact on ecosystems. In this context, removing harmful chemicals via photocatalysis has tremendous potential as a depollution method, utilizing freely available solar light and catalytic materials with low or negligible ecotoxicity. The main drawbacks, which aren’t often addressed in the available literature, are the formation of harmful intermediate products, low reaction rates, limited catalyst stability, and difficult catalyst recovery. In most cases, published works assess the efficiency of tested photocatalysts from pollutant degradation studies, whereas identifying and quantifying by-products is not often conducted. This review summarizes the recent advances reported for the photocatalytic removal of some organic (e.g., alcohols, carboxylic acids, volatile organic compounds, phenol) and inorganic (e.g., NO3−) contaminants. The efficiency of various UV- and visible-light active photocatalysts and the reaction degradation pathways were explained, emphasizing the main factors contributing to their mineralization. The reaction mechanisms, the identification and quantification of degradation intermediates, and the implication of reactive active species (ROS) were discussed and analyzed for each category of model target pollutant. Additionally, the actual challenges and future photocatalytic approaches to improve environmental remediation were presented.

malik B., kaur sandhu K.

Heavy metals are introduced into the environment by naturally occurring phenomenon like volcanic eruption, rock weathering and many more. As well as by human activities are also equally engaged in the contamination of the environment such as industrial discharge, excessive automotive use, resource extraction, metallurgy, anthropogenic activities, metallurgy, and so on. Because of the dramatic increase in health hazards that is directly associated with vital heavy metal exposure. Though many heavy metals are vital for survival on Earth, they can also have a negative and significant impact on all living bodies (such as plants, animals, and microorganisms). They can damage tissues and even lead to severe organ damage/impairment, the functioning of some organs can also be severely affected, neurological disorders can eventuate, and even lead to death. Heavy metal even adds adverse effect on the function of reproduction like drastic change in sperm, count in males, imbalance of hormones, motility etc. Efficiency of reproduction is get affected by hazardous heavy metals. Toxicity factor depend on various subfactors like the amount of consumption (dose), route, age group, and other genetics parameters. These toxicants can induce efficiency of multiple organs, though at low dosage or exposure.

Althomali R.H., Alamry K.A., Hussein M.A., Guedes R.M.

The adsorption and removal performance of CMC-based 4-aminophenazone and doped MWCNTs NC was investigated CV and BG dyes. The results demonstrate the excellent potential of A-PH-CMC/MWCNTs nanocomposites as a material for CV and BG dye removal.

Rahman S., Rahman Khan M.M., Deb B., Dana S.I., Ahmed M.K.

Pyrrole (Py) and thiophene (Th) based copolymers of poly(Py-co-Th) and its composites poly(Py-co-Th)/ZnO were fabricated by varying the addition of ZnO ranging from 1-15 wt% by chemical oxidative polymerization approach. The photocatalytic performance of prepared poly(Py-co-Th)/ZnO composites was assessed together with the interaction study of ZnO with poly(Py-co-Th). The formation of poly(Py-co-Th) copolymer and poly(Py-co-Th)/ZnO composites were confirmed by FTIR, UV−Vis, and photoluminescence (PL) spectroscopy. The prepared poly(Py-co-Th)/ZnO composites showed excellent photocatalytic representation towards methylene blue (MB) degradation in comparison to the poly(Py-co-Th) copolymer. All the composites showed 90.2–95.3% dye removal after the time span of 420 min which is far better compared to the poly(Th-co-Py) copolymer (84.3%). Thus, the poly(Py-co-Th)/ZnO composites showed promising prospects for the removal of organic dye for water purifications. These results may provide a unique insight to fabricate copolymer-based poly(Py-co-Th)/ZnO photocatalysts for organic pollutants management.

Zango Z.U., Garba A., Garba Z.N., Zango M.U., Usman F., Lim J.

Clay minerals have been recognized as one of the cheap and effective materials for wastewater remediation. Among the various clay minerals, montmorillonite (MMT) has received much attention due to its wide availability, low-cost and promising properties such as high porosity, mechanical strength, and cation exchange capacity. Additionally, MMT has high swelling properties. These features make it an ideal material for wastewater remediation applications. In addition, it possessed good cationic exchange capacity, making it easier to interact with various molecules. MMT and its composites exhibited good selectivity and catalytic activity for contaminants elimination from wastewater. Surface modification and functionalization have been identified as a way to improve the MMT’s adsorptive performance and endow it with light and light-harnessing properties. Thus, MMT composites, especially metal and metal-oxide nanoparticles, have shown good adsorption and photocatalytic activity toward the elimination/mineralization of various contaminants such as dyes, pharmaceuticals, heavy metals, and other organic and inorganic species. As such, MMT and its composites can be adopted as potential materials for wastewater remediation.

Lin D., Li Y., Huang Y., Qin W., Loy D.A., Chen H., Zhang Q., Wu Z.

In this study, citric acid modified cellulose nanocrystals (MCNC) and silica aerogel (SA) were used as reinforcing agents and added to polyvinyl alcohol (PVA) in different proportions to prepare composite films with excellent mechanical and barrier properties. After modification with citric acid, MCNC successfully contained ester bonds. SEM and FTIR results showed that MCNC and SA were uniformly dispersed in the PVA matrix and formed a compact structure. XRD results showed that there were physical interactions between the reinforcing agents and PVA, which improved the thermal stability of the film. Meanwhile, the composite film obtained good barrier properties after adding 0.5 % MCNC and 1.5 % SA. The carbon dioxide permeability decreased by 66.01 % and the oxygen permeability decreased by 69.46 % (23 °C, 50 % RH) and 40.14 % (38 °C, 90 % RH). The tensile strength increased to 43.79 MPa. Therefore, the composite film can be widely used in the packaging of food, medicine, etc.