Search

The availability of toxic pollutants in the water is a primary obstacle to utilizing the water for drinking purposes. So, scientists are making efforts to develop cutting-edge, affordable, renewable, and environmentally friendly methods for wastewater treatment to address the water shortage challenges and protect human health from serious diseases. Many wastewater treatment techniques have been developed for water treatment, including adsorption, ion exchange, membrane separation, co-precipitation oxidation, and biochemical processes. In all these water treatment techniques, adsorption is one of the strong candidates to eliminate the Cd2+ from water because of its economic feasibility and short route. The pristine nanomaterials possessed poorer adsorption capacity than their composites. The Cd2+ adsorption capacity is in the decreasing order of the graphene oxides (GO), MXenes, multi-walled carbon nanotubes (MWCNTs), and layered double hydroxides (LDHs). This indicates that the GO is the most suitable choice for Cd2+ adsorption. In the current review, the authors discussed the performance of the MXene, graphene, GO, LDHs, and carbon nanotube (CNT)-based adsorbents. This study provides with a comparative analysis of the properties of all mentioned nanomaterials. A brief introduction of the synthesizing routes and the impact of various factors on the performance of nanomaterials have been discussed. Finally, the prospects and future challenges associated with the nanomaterials have been highlighted. In a nutshell, the porous nature, high inter-layer space, and significant specific surface area (SSA) of GO makes them an ideal candidate for the adsorption of Cd2+. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) and MXene are innovative materials of 2D heterostructured nanomaterials that evolved and found many applications. Because of the outstanding porosity, high specific surface area (SSA), environmental friendliness, structural properties, and chemical, mechanical, and thermal stability of GO and MXene are extensively utilized to manufacture Li-batteries, hydrogen storage semiconductors and water desalination membranes. The GO-based composites are superior to MXene-based composites in desalinating the water because of their excellent SSA (2391 m2/g), high mechanical strength (470 GPa), and Electrical conductivity (4.12 × 10−5 S.cm−1) and thermal conductivity (2–1000 W/mk). Compared to GO, MXene has more inferiority regarding stability and recyclability. The highest salt rejection capacity of GO-CD-PA and MXene slit membranes are 99.9 % and > 90 %, respectively. Adding polymer-based nanomaterial can enhance the salt rejection performance chemical, thermal and mechanical stability of GO and MXene. Adding polymers also positively impacts the unit-fouling characteristics of GO and MXene. The current review paper compares the physical and chemical properties of GO and MXene that have a viable impact on the desalination of the GO and MXene-based membranes. The synthesizing route is another factor that significantly impacts the structure and desalination performance of GO and MXene. Both 2D materials synthesized via traditional techniques have poor desalination capability compared to those synthesized via advanced or modified synthesizing techniques. Membrane fouling is a critical issue to limit the applications of membranes, and ways to handle these issues are addressed. This paper briefly introduces the various synthesizing techniques of GO and MXene. The basic objective of the paper is to compare the desalination performance of GO and MXene. The challenges and prospects of GO and Mxene were discussed. The authors believe this contribution addresses important and recent problems related to the desalination industry. • Comparison mechanisms of the Graphene and MXene-based membranes are highlighted. • Holistic characteristics of Graphene and MXene were narrated. • Graphene has superb desalination capability, recyclability and stability compared to MXene-based membranes. • Challenges and prospects associated with Graphene and MXene-based nanomaterial have been discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Lipase enzyme extracted from Porcine Pancreas was immobilized onto the GO. • Comparison of the immobilized enzymes performance and free enzymes. • Adsorption isotherm and kinetic studies. • The enzyme activity, and reusability of the immobilized Lipase. Immobilization of enzymes improves their stability, performance, reusability, and recovery. This study investigated the removal of Azo dyes from industrial wastewater effluent using immobilized Lipase enzyme on Graphene Oxide (GO) in batch mode. The Lipase enzyme extracted from Porcine Pancreas was immobilized onto the GO via adsorption, where the enzymes are attached to the support by intermolecular forces. This study aims to investigate the immobilization efficiency of Lipase on the GO and determine the effect of parameters such as Lipase concentration, pH, and temperature on the enzyme activity. The results showed that the enzyme activity increased with the Lipase concentration, pH and temperature until an optimum point was achieved. The saturation of support surface pores causes the loss of enzyme activity due to the excessive Lipase enzyme, structural deformation of the support surface and enzyme denaturation due to extreme pH and temperature. The immobilized Lipase activity and free Lipase activity were compared. The optimum Lipase concentration is 6 mg/mL, with the greatest immobilization efficiency and highest enzyme activity. Besides, the optimum pH for the highest immobilized Lipase activity is 8.0, and the optimum temperature is 40 °C. The characterization results confirmed the immobilization of the Lipase enzyme. Adsorption isotherm and kinetic studies are also carried out to investigate the dye removal performances. The highest Azo dye removal efficiency obtained is 89.47% at 240 min of contact time and 5 mg/L of initial dye concentration. Further, the reusability of the immobilized Lipase was also investigated and found that the immobilized Lipase can be reused up to four cycles. Thus, the adsorption of dyes through immobilized lipase on GO can significantly impact various industrial sectors. [ABSTRACT FROM AUTHOR]

Aerogel based on reduced graphene oxide was synthesized using supercritical methods of drying the hydrogel in isopropanol. The synthesis technique involves the deposition of iron hydroxides on graphene layers, then their reduction in supercritical isopropyl alcohol to iron oxides (Fe 3 O 4 and γ-Fe 2 O 3). Results revealed that synthesized adsorbents Graphene aerogel (GA) and GA/Fe show excellent high gravimetric methane adsorption with an achievable capacity of 2.5 g/g and 3.6 g/g, respectively, in the pressure range of 0.5–10 MPa and 298 K, which is more than seven times higher than the requirements established by the US Department of Energy for the gravimetric capacity of a porous material for methane storage. However, at high gravimetric absorption, the volume absorption was 104 m3 (STP)/m3 and 102 m3 (STP)/m3 for (GA) and (GA/Fe), respectively. It should be noted that the performance characteristics of aerogels, in general, are comparable to adsorbents of other classes. A generalized flow-chart for obtaining the graphene aerogel. [Display omitted] [ABSTRACT FROM AUTHOR]