Search

Addressing the critical issue of water pollution, this review article emphasizes the need to remove hazardous dyes and phenolic compounds from wastewater. These pollutants pose severe risks due to their toxic, mutagenic, and carcinogenic properties. The study explores various techniques for the remediation of organic contaminants from wastewater, including an enzymatic approach. A significant challenge in enzymatic wastewater treatment is the loss of enzyme activity and difficulty in recovery post-treatment. To mitigate these issues, this review examines the strategy of immobilizing enzymes on newly developed nanostructured materials like graphene, carbon nanotubes (CNTs), and metal–organic frameworks (MOFs). These materials offer high surface areas, excellent porosity, and ample anchoring sites for effective enzyme immobilization. The review evaluates recent research on enzyme immobilization on these supports and their applications in biocatalytic nanoparticles. It also analyzes the impact of operational factors (e.g., time, pH, and temperature) on dye and phenolic compound removal from wastewater using these enzymes. Despite promising outcomes, this review acknowledges the challenges for large-scale implementation and offers recommendations for future research to tackle these obstacles. This review concludes by suggesting that enzyme immobilization on these emerging materials could present a sustainable, environmentally friendly solution to the escalating water pollution crisis. [ABSTRACT FROM AUTHOR]

Inorganically crosslinked polymers have been intensively implemented for conformance control treatments in oil and gas wells at low temperatures (<90°C) because of their faster gelation time compared to organically crosslinked gels. Crosslinkers such as chromium acetate are known to be toxic, and aluminium‐based alternatives have been introduced. This study aims to investigate the impact of aluminium acetate (AlAc) particle size on the gelation kinetics of polyacrylamide (PAM)‐based gels at a pH of 5 and temperature of 75°C. Moreover, bentonite is used as an additive to delay the crosslinking of PAM/AlAc gels. Reducing the particle size increases the specific surface area of the particles and provides more crosslinking sites. Therefore, lower PAM concentrations (up to 5 wt.%) could be used without AlAc settling. Using 7 wt.% PAM/1 wt.% AlAc with sizes of 25 and 48 μm revealed a crosslinking time of 17 and 115 min, respectively. The addition of bentonite at low crosslinker concentrations (0.5–1 wt.%) did not decrease the gel strength of 7 wt.% PAM/1 wt.% AlAc significantly. The gelation time was extended after adding 1 wt.% bentonite to the formulation where the delay was attributed to the adsorption of AlAc on the bentonite surface that was illustrated by molecular simulation. [ABSTRACT FROM AUTHOR]

The potential crosslinking of three types of nitrogen‐containing functionalized silica (TAAcONa, guanidine, and triamine) with polyacrylamide (PAM) has been investigated. Only triamine silica was able to crosslink with PAM, producing barely flowing gel with storage modulus of around 700 Pa. Micro differential scanning calorimeter (μDSC) analysis illustrated exothermic peaks indicating crosslinking of PAM with triamine and polyethyleneimine (PEI), with crosslinking onset temperatures of 80°C and 84°C. TGA analysis showed the thermal stability of the functionalized silica up to temperatures of more than 200°C. In the domain of study (up to 130°C), TAAcONa silica exhibited the highest weight loss of 5%. Different kinetic models were used to identify the degree of crosslinking and PAM/PEI has shown diffusion‐controlled reaction unlike PAM/triamine‐functionalized silica. The crosslinking mechanism of the new crosslinker is proposed to be similar to that of the PAM/PEI system. Yet, functionalized silica‐based gels are more stable and possess higher strength. [ABSTRACT FROM AUTHOR]