The adsorption of direct red 23 as a toxic pollutant in aqueous solution by using surface modified metal-organic framework containing tricarboxylic acid benzene ligand

In this research, Cu-BTC (C-BTC) metal-organic framework (MOF) was prepared and characterized. The synthesized C-BTC was modified with 3-aminopropyltrimethoxysilane to synthesize C-BTC-NH2. The ability to remove the direct red 23 (DR-23) dye by the synthesized materials (C-BTC and C-BTC-NH2) as adsorbents was investigated. The effect of operational parameters on dye removal was investigated. The results showed that the ability of the modified adsorbent (C-BTC-NH2) to adsorbed dye is more than the raw adsorbent (C-BTC). The amount of dye adsorption is high in acidic pH values. Increasing the amount of adsorbent and decreasing the pH of solution causes an increase in the percentage of dye adsorption and enhance in the DR-23 concentration causes a decrease in the percentage of DR-23 removal. The results of dye adsorption were matched with different isotherms and removal process followed the Langmuir isotherm. The experimental data exhibited a good fit with the Langmuir isotherm model (R2 = 0.9637), with the maximum adsorption capacity (Q0) of the calculated as 89.2857 and 2500 mg/g for DR-23 removal by C-BTC and C-BTC-NH2, respectively. Dye adsorption follows pseudo-second-order kinetics and k2 is PSO rate constant 0.0028 and 0.010 for by C-BTC and C-BTC-NH2, respectively. The data presented that C-BTC-NH2 as a modified adsorbent has high removal ability and is appropriate adsorbent for dye adsorption from aqueous solution.