Construction of a cost-effective cetyltrimethylammonium bromide-impregnated fly ash as efficient adsorbent for removal toxic heavy metal ions

The objective of this contribution is to construct cetyltrimethylammonium bromide-impregnated fly ash (CTAB-FA) adsorbent for the removal of heavy metal ions in wastewater. In the present work, cost-effective CTAB-FA adsorbent was successfully fabricated for removal of As 3+ , Cd 2+ , Cr 6+ , and Pb²⁺ ions. The prepared CTAB-FA adsorbent was examined by N2 adsorption-desorption SEM, zeta potential, and XRD. FTIR verified the existence of hydroxyl, carbonyl and amino functional groups with high organic content on the surface of FA. The maximum removal of As 3+ , Cd 2+ , Cr 6+ , and Pb²⁺ ions over CTAB-FA adsorbent was determined in acidic medium due to CTAB-FA adsorbent has about 4.22 the point zero charge. The results indicated that the optimal conditions for all parameters were achieved to obtain highest removal efficiency and adsorption capacity such as CTAB-FA dosage at 0.3 g, 100 mL of volume of solution, pH at 4, and 1000 g/L metal ions concentrations for 5 min contact time at 25 °C. Batch adsorption runs showed that the functionalization of FA by CTAB presented the fastest adsorption kinetics with the highest removal efficiency and adsorption capacity of 100% and 333 mg g -1 towards all metal ions As 3+ , Cd 2+ , Cr 6+ , and Pb²⁺ under the above optimum conditions. The successful impregnation of the CTAB onto FA surface offers an effective approach to design favourable low cost CTAB-FA adsorbent for removal As 3+ , Cd 2+ , Cr 6+ , and Pb²⁺ ions from real wastewater. The optimal operation parameters, isotherm, and kinetic are explored. The general importance of this work lies in its contribution to permanent environmental treatment by destroying industrial waste such as fly ash and converting it into a valuable resource for water purification. The extensive study of adsorbent kinetics, isotherms, and operating parameters provides significant insights for future development of low-cost adsorbent technologies. In addition, the success of CTAB impregnation opens new avenues for surface modification of other industrial by-products, promotes circular economy practices, and reduces environmental impact. • FA was grafted with cetyltrimethylammonium bromide (CTAB-FA) for removal of metal ions. • Removal efficiency of 100% for all the As 3+ , Cd 2+ , Cr 6+ , and Pb 2+ ions within 5 min. • CTAB-FA exhibited adsorption capacity of 330 mg/g, nearly 30 times higher than FA. • CTAB-FA obeyed the pseudo second-order kinetic and Langmuir isotherm modeling. • CTAB-FA revealed enhanced adsorbent ability from tertiary-treated wastewater.