The new CO₃²⁻/Cl⁻ layered double hydroxides (LDHs) (Mg_(3−3v)Zn_3v)/(Al_(1−w)Fe_w) were synthesized and calcined at 450 °C (CLDH), where v and w = 0, 0.1, 0.2, and/or 1, as adsorbents to remove anionic hazards such as Isolan Dark Blue 2SGL-01 (IDB) and CrO₄²⁻ from polluted wastewater. The products were characterized by powder X-ray diffractometry, Fourier transform infra-red spectra, thermogravimetric analysis, elemental analysis, scanning electron microscope, magnetic susceptibility and specific surface area measurements. The effect of composition of LDH’s on their uptake capacities (q_e) for IDB and chromate ions were studied. CLDH’s were more effective in removing anionic hazards than LDH, in particular with IDB and for v and w = 0.1 and/or 0.2. High adsorption capacities were obtained up to 438 and 46.3 mg g⁻¹ (30.1 and 15.7% of the theoretical capacities), for IDB and chromate, respectively. Fe-containing LDHs could be magnetically separated either as-synthesized or loaded.