Application of waste tyre-based powdered activated carbon for the adsorptive removal of cylindrospermopsin toxins from environmental matrices: Optimization using response surface methodology and desirability function

Application of Activated Carbon Banana Peel Coated with Al2O3-Chitosan for the Adsorptive Removal of Lead and Cadmium from Wastewater

This study was aimed at evaluating the adsorption capacity of novel banana peel activated carbon (BPAC) modified with Al₃O₂@chitosan for the removal of cadmium (Cd²⁺) and lead (Pb²⁺) from wastewater. Characterization techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transformed infrared (FTIR) spectroscopy, and Brunauer-Emmett-Teller analysis confirmed the synthesized BPAC@Al₃O₂@chitosan composite material. The univariate approach was used to study the influence of different experimental parameters (such as adsorbent mass, sample pH, and contact time) that affects simultaneous removal of Cd²⁺ and Pb²⁺ ions. Kinetic results showed that adsorption favored the pseudo-second-order kinetic model, whereas the adsorption of Cd²⁺ and Pb²⁺ was best described by the Langmuir model and the adsorption capacity for Cd²⁺ and Pb²⁺ was 46.9 mg g^-1 and 57.1 mg g^-1, respectively, for monolayer adsorption. It was shown the BPAC composite can be re-used until the third cycle of adsorption-desorption (% Re > 80). Based on the obtained results, it can be concluded that the prepared BPAC@Al₃O₂@chitosan composite material is cost effective, as it is generated from waste banana peels and can be re-used. In addition, the prepared material was able to remove Cd²⁺ and Pb²⁺ up to 99.9%.

Fabrication of High Yield Photoluminescent Quantized Graphene Nanodiscs for Supercapacitor Devices

In this work, we produced high yield quantized nitrogen-doped graphene nanodiscs from waste tires via a one-step process under high pressure and temperature using a homemade stainless steel reactor without using any chemical additives. Reaction temperature played a vital role in the preparation process. By increasing the temperature to a level between 600 and 1100 °C, the carbon atoms rearranged themselves to build a mixed graphene structure of nanodiscs and quantum dots. The obtained graphene exhibits excellent capacitance and long life cycle stability as an electrode in supercapacitor devices. The specific capacitance rose to 161.24 F/g with a high power density of 733.3 W/kg, and the energy density reached 27.1 Wh/kg. The finding of this work is not only to provide a solution to get rid of hazardous materials but also to give awareness of turning these hazardous materials into a cost-effective and economical nanomaterial; in another, this approach sheds light on the promising power uses of waste.

Recent Advancements in the Removal of Cyanotoxins from Water Using Conventional and Modified Adsorbents—A Contemporary Review

The prevalence of cyanobacteria is increasing in freshwaters due to climate change, eutrophication, and their ability to adapt and thrive in changing environmental conditions. In response to various environmental pressures, they produce toxins known as cyanotoxins, which impair water quality significantly. Prolonged human exposure to cyanotoxins, such as microcystins, cylindrospermopsin, saxitoxins, and anatoxin through drinking water can cause severe health effects. Conventional water treatment processes are not effective in removing these cyanotoxins in water and advanced water treatment processes are often used instead. Among the advanced water treatment methods, adsorption is advantageous compared to other methods because of its affordability and design simplicity for cyanotoxins removal. This article provides a current review of recent developments in cyanotoxin removal using both conventional and modified adsorbents. Given the different cyanotoxins removal capacities and cost of conventional and modified adsorbents, a future outlook, as well as suggestions are provided to achieve optimal cyanotoxin removal through adsorption.