Activated carbon/titanium dioxide (AC/TiO₂) nanohybrids were synthesized by a hydrothermal technique using various weight percent of commercial AC and were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA). The synthesized nanohybrids were applied to photodegradation of Reactive Red-35 (RR-35) dye in aqueous solution using sunlight. Due to the synergistic effect of adsorption and photodegradation activity, AC/TiO₂ nanohybrids were more efficient in treating the aqueous dye solution than that of AC and TiO₂. The maximum (95%) RR-35 dye removal from the water was obtained with 20 wt% AC/TiO₂ within 30 min at natural pH of 5.6. The possible photodegradation mechanism of RR-35 dye with AC/TiO₂ was discussed from the scavenger test. Moreover, AC/TiO₂ was found to be suitable for long-term repeated applications through recyclability experiments. Therefore, AC/TiO₂ nanohybrid is a promising photocatalyst for treating azo dyes especially RR-35 from water.

An unprecedented flood of end-of-life cells is being produced by the exponential expansion of lithium-ion battery (LIB) deployment across electric mobility, portable electronics, and stationary storage. Within the next ten years, this wave is expected to reach millions of tons yearly. Recovering the anode and cathode active materials from this spent-battery stream is central to closing the loop on critical raw materials such as lithium, cobalt, nickel, manganese, and graphite, and to decoupling battery manufacturing from primary mining. This review provides an integrated assessment of the technological, economic, environmental, and regulatory landscape of anode and cathode recovery from spent LIBs. We first summarize the current industrial status of LIB recycling and the structural limitations of conventional pyrometallurgical smelting, motivating the shift toward hydrometallurgical, direct-regeneration, and cathode-upcycling routes that preserve rather than destroy the crystalline architecture of active materials. We then examine how artificial intelligence is beginning to reshape battery sorting, disassembly, and circular manufacturing, and how digital twins are enabling intelligent, self-optimizing recycling plants. Techno-economic and life-cycle assessments are synthesized to compare the cost structures, profitability, and greenhouse-gas footprints of pyrometallurgical, hydrometallurgical, and direct-recycling pathways, and the evolving policy landscape anchored by the EU Battery Regulation (EU) 2023/1542 is reviewed as a driver of circularity. Finally, persistent research gaps spanning graphite anode regeneration, black-mass heterogeneity, solid-state and sodium-ion battery recyclability, and standardization are identified, and a future outlook is offered for a resilient, low-carbon, circular battery materials economy.