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

In the current study, a novel composite (Fe 3 O 4 @MnO 2 @Al 2 O 3 ) 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 R 2 (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 R 2 (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, (Fe 3 O 4 @MnO 2 @Al 2 O 3 ) can be used as efficient sorbent for removing Cd and crystal violet dye from synthetic industrial wastewater.