Synthesis of New Composite Adsorbents for Removing Heavy Metals and Dyes from Aqueous Solution

In the current study, a novel composite (Fe3O4 @MnO2@Al2O3) was prepared to remove crystal violet dye and cadmium from aqueous solutions. The coprecipitation method was utilized to synthesize the composite. Batch studies were carried out using a contact period of 0.5–3 hours, an initial crystal violet and cadmium content of 50–200 mg/L, an agitation speed of 50–200 rpm, a pH of 4–12, and a composite dosage of 0.2–1.0 g per 50 mL of contaminated solution. The isotherm and kinetics models were formulated the experimental data. XRD, SEM-EDS, and FTIR analyses were utilized for composite characterization. The results revealed that the removal efficacy of crystal violet dye was 99.311% at 1 g of adsorbent, pH 12, 50 mg/L, 1 hour, and 200 rpm. The removal efficacy for cadmium (Cd) is 99.7296% at 1 g of sorbent mass at pH 6, 50 mg/L, 1 hour, and 200 rpm. The outcomes demonstrated that the Langmuir model could accurately depict the sorption of crystal violet dye onto the composite with R2 (0.9882) and SSE (0.7084). On the basis of Freundlich, the capacity of the composite to reflect cadmium sorption was assessed by its highest R2(0.8947) and lowest SSE (8.5149). The pseudo-second-order model is a more realistic way to explain how cadmium and crystal violet dye sorb onto the composite. The results showed that the composite is effective in eliminating target pollutants, since cadmium has a maximum adsorption capacity of 48.5052 mg/g and crystal violet dye has a capacity of 40.9682 mg/g. Therefore, (Fe3O4 @MnO2@Al2O3) can be used as efficient sorbent for removing Cd and crystal violet dye from synthetic industrial wastewater.