| Summary: | The aim of this research was to explore the removal of Red G and Bordeaux B dyes from water using a packed bed column with conventional carbon (<i>C<sub>-conv</sub></i>) and iron-modified activated carbon <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>C</mi><msub><msub><mrow></mrow><mtext>-</mtext></msub><mrow><mi>F</mi><mi>e</mi><mi>C</mi><msub><mi>l</mi><mn>3</mn></msub></mrow></msub></mrow></semantics></math></inline-formula>). The bands increased in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>C</mi><msub><msub><mrow></mrow><mtext>-</mtext></msub><mrow><mi>F</mi><mi>e</mi><mi>C</mi><msub><mi>l</mi><mn>3</mn></msub></mrow></msub></mrow></semantics></math></inline-formula>, corresponding to groups already existing in <i>C<sub>-conv</sub></i>, such as C = C and C-C, and the appearance of new groups, such as C-O, C-Cl, Fe-Cl and Fe-O. The total ash content (<i>C<sub>T</sub></i>) was <i>C<sub>T</sub></i> = (10.53 ± 0.12 and 8.98 ± 0.21)% for <i>C<sub>-conv</sub></i> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>C</mi><msub><msub><mrow></mrow><mtext>-</mtext></msub><mrow><mi>F</mi><mi>e</mi><mi>C</mi><msub><mi>l</mi><mn>3</mn></msub></mrow></msub></mrow></semantics></math></inline-formula>, respectively. A molecular structure in the shape of a cross was noticed in Bordeaux B, which was less complex and smaller than the one in Red G. For fixed-bed columns, the carbon fraction was (0.43 and 0.85) mm. The pH of the adsorbents was 8.55 for <i>C<sub>-conv</sub></i> and 4.14 for <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>C</mi><msub><msub><mrow></mrow><mtext>-</mtext></msub><mrow><mi>F</mi><mi>e</mi><mi>C</mi><msub><mi>l</mi><mn>3</mn></msub></mrow></msub></mrow></semantics></math></inline-formula>. Breakthrough curves were obtained and the Thomas model (TM) and Yoon–Nelson model (YNM) were applied. The sorption capacity of Bordeaux B on <i>C<sub>-conv</sub></i> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>C</mi><msub><msub><mrow></mrow><mtext>-</mtext></msub><mrow><mi>F</mi><mi>e</mi><mi>C</mi><msub><mi>l</mi><mn>3</mn></msub></mrow></msub></mrow></semantics></math></inline-formula> was <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>q</mi><mrow><mi>T</mi><mi>H</mi></mrow></msub></mrow></semantics></math></inline-formula>: (237.88 and 216.21) mg/g, respectively, but the one of Red G was <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>q</mi><mrow><mi>T</mi><mi>H</mi></mrow></msub></mrow></semantics></math></inline-formula>: (338.46 and 329.42) mg/g. The dye removal (R<sub>T</sub>) was over 55%.
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