A simple approach for synthesizing a highly adsorbent composite was described for the uptake of heavy metal ions from wastewater. A simple approach for synthesizing a highly adsorbent composite was also described for the elimination of heavy metal ions from contaminated water. The nanocomposite was synthesized via a polymer grafting of chitosan on the activated carbon surface, followed by a stacking process with the layers of montmorillonite clay. The spectroscopic analyses were exploited to confirm the composite structure of the prepared materials. Various adsorption parameters, such as pH, initial concentration, and adsorption time, were assessed. The results showed that the adsorption capacity of the composite for Pb²⁺ ions increased as the pH increased until it reached pH 5.5. The maximum adsorption capacity was observed at an initial Pb²⁺ level of 20 mg/L and a contact time of 150 min. Kinetic models were evaluated, and the pseudo second-order model showed the best match. The adsorption isotherm data were processed by fitting the model with different isotherm behaviors, and the Langmuir isotherm was found to be the most suitable for the system. The maximum adsorption capacity for Pb²⁺ ion on the MMT/CS/AC composite was found to be 50 mg/g at pH 5.5. Furthermore, the composite maintained a high adsorption capability of 85% for five adsorption–desorption cycles. Overall, this composite is envisioned as an addition to the market of wastewater remediation technology due to its chemical structure, which provides influential functional groups for wastewater treatment.

In this study, aminoterephthalic acid (ATPA) modified oxidized activated carbon (AC) was prepared (AC@ATPA). The (AC@ATPA) composite was applied for removal of malachite green (MG) from aqueous medium. The obtained AC@ATPA composite was characterized by varying techniques such as TGA, FTIR, SEM, EDX, XRD and zeta potential. The results reveal that the optimum parameter conditions for the maximum MG dye ions adsorption were found to be pH- 6, adsorbents amount-30 mg, equilibrium time reached within 240 min at initial concentration 20 mg/L and room temperature. The adsorption process fitted well with Langmuir isotherm and pseudo-first-order kinetic model with the maximum adsorption capacities for MG of 188.7 mg/g.

This review critically discussed recent developments in hydrothermal carbonization (HTC) of food waste and its valorization to solid fuel. Food waste properties and fundamentals of the HTC reactor were also covered. The review further discussed the effect of temperature, contact time, pressure, water–biomass ratio, and heating rate on the HTC of food waste on the physiochemical properties of hydrochar. Literature review of the properties of the hydrochar produced from food waste in different studies shows that it possesses elemental, proximate, and energy properties that are comparable to sub-bituminous coal and may be used directly as fuel or co-combusted with coal. This work conclusively identified the existing research gaps and provided recommendation for future investigations.