1：Experimental Design and Method Selection:

The study used solution combustion synthesis to prepare ZnO nanoparticles with different fuels (coffee husk extract and sugar). Adsorption experiments were conducted in batch mode to evaluate the removal of Congo red dye, with parameters like pH, temperature, initial dye concentration, adsorbent dose, and contact time varied. Isotherm and kinetic models were applied to analyze the data.

2：Sample Selection and Data Sources:

Coffee husk was collected from a specific location in India, and chemicals like zinc nitrate hexahydrate and Congo red were procured from S D Fine-Chem Limited. Double distilled water was used throughout.

3：List of Experimental Equipment and Materials:

Equipment included a muffle furnace for synthesis, XRD (Rigaku Smartlabs), SEM (JEOL JSM-840A), TEM (JEOL JEM-301), BET surface area analyzer (MicrotracBEL), FTIR spectrometer (Perkin Elmer Spectrum 1000), orbital shaker, centrifuge, and UV-Vis spectrophotometer for dye concentration measurement. Materials included zinc nitrate hexahydrate, Congo red, coffee husk, sugar, NaOH, HCl, and NaCl.

4：Experimental Procedures and Operational Workflow:

ZnO nanoparticles were synthesized by dissolving zinc nitrate in fuel (coffee husk extract or sugar solution), stirring, and combusting in a muffle furnace at 500°C. Adsorption experiments involved agitating dye solutions with adsorbent, adjusting pH, and measuring absorbance at 497 nm after centrifugation. Zero-point charge was determined by solid addition method.

5：Data Analysis Methods:

Data were analyzed using linear regression in Microsoft Excel 2016. Isotherm models (Langmuir, Freundlich, Temkin, Dubinin-Radushkevitch) and kinetic models (pseudo-first order, pseudo-second order, Weber-Morris intraparticle diffusion, Bangham) were fitted. Thermodynamic parameters were calculated from van't Hoff plots.