Studying the adsorption of some organic dyes from their aqueous solutions by hemp surface and its composites

The excess of dye in wastewater polluted the environment, making it difficult to remove the color from the aquatic system properly. The goal of this research was to recycle hemp waste, an environmental husk material, as effective adsorbent surfaces for the removal of cationic (Janus green) and anionic (Congo red) dyes from aqueous solutions. The four surfaces of hemp waste (hemp powder, hemp fiber, hemp-ligand, and hemp complex) have been characterized by FT-IR, XRD, FESEM, EDX, BET, and GC mass analysis. The results established adsorbents' efficient adsorption characteristics for JG and CR dyes. The results of the adsorption process revealed that JG and CR dyes were efficiently eliminated, removal rate of more than 87% under optimal conditions, which included a contact time of 60 minutes, a dose of 1 g/L of (hemp powder and hemp fiber) and 2 g/L of (hemp-ligand and hemp complex), and an initial JG dye concentration of 75 mg/L and 40 mg/L for CR dye. By utilizing Langmuir, Freundlich, and Temkin isotherm models were found to be effective in defining the equilibrium of the adsorption process. In this study, the equilibrium adsorption data follows the Langmuir isotherm model. The linear Langmuir model has the highest adsorption at ambient temperature. On the other hand, the kinetic model's data revealed a stronger correlation coefficient (R2) value for the pseudo-second order (PSO) model than the pseudo-first order (PFO) model in characterizing the two dyes adsorption process onto all four adsorbents. The thermodynamic parameters (∆G°, ∆H°, and ∆S°) indicate that the adsorption process was spontaneous, practicable, and endothermic. Finally, this study proposes a novel approach to creating useful and economical adsorbents from hemp waste to remove contaminants from water. This supports the application of hemp surface residue as a novel adsorbent for various poisonous dyes and hazardous organic