Adsorptive removal of organic load and color from synthetic textile effluent in a fixed-bed column: RSM-based optimization

The treatment of a synthetic textile effluent was investigated using fixed-bed column adsorption, with operational conditions optimized through Response Surface Methodology. Incinerated pine cone (PC), employed as the adsorbent material, was characterized by SEM, EDX, FTIR and BET analyses, revealing the presence of functional groups favorable to adsorption. Experimental optimization showed that the combination of a particle size of 40 µm, a flow rate of 7 mL/min, and a bed height of 10 cm constituted the most effective configuration. Under these experimental conditions, Chemical Oxygen Demand (COD) was reduced by over 98%, decreasing from 1814 mg/L to 21 mg/L, demonstrating highly effective removal of the organic load. Concurrently, substantial effluent clarification was observed, with a reduction of suspended solids (SS) from 872 mg/L to 26 mg/L. Regarding color, the system allowed for near-complete decolorization of the effluent. Removal efficiencies ranged from 96.97% to 99.97%, with an average value of 99.4%, confirming the effectiveness of the material in adsorbing Congo Red as well as other chromophoric molecules present. These performances reflect the strong affinity of the incinerated pine cone for anionic dyes, attributed to the synergy between its developed porous structure and the surface functional groups. Collectively, the results demonstrate that incinerated pine cones constitute a low-cost and efficient natural bioadsorbent for textile effluent treatment. Furthermore, the study underscores the effectiveness of Response Surface Methodology as a reliable tool for optimizing fixed-bed column adsorption processes, thus facilitating potential scale-up for industrial applications. • Fixed-bed adsorption used for textile effluent treatment with incinerated pine cone bioadsorbent. • Pine cone shows porous structure and functional groups favorable to adsorption (SEM, FTIR, BET). • RSM optimization identified optimal conditions: 40 µm, 7 mL/min, 10 cm bed height. • COD and suspended solids removal exceeded 98% with near-complete decolorization. • Low-cost, sustainable bioadsorbent with strong potential for industrial scale-up.