Study On The Treatment Of Anionic And Cationic Dye Wastewater By Multifunctional Aminocarboxyl Silica Adsorbent

For the treatment of dye wastewater,aminopolycarboxylic acid compounds with both ion exchange and metal chelating properties are of great advantage.However,in previous studies,ammonia-carboxylic compounds were applied directly in liquid form,which are not easily recovered and are prone to secondary pollution.In addition,studies have shown that there is a direct relationship between the multifunctional properties of these compounds and the number of functional groups they contain.Considering the above problems,different aminocarboxylates ethylenediaminodisuccinate（EDDS）,iminodisuccinate（IDS）and iminodiacetic acid（IDA）were selected as modified ligands in this study to produce a new multifunctional silica adsorbent,and its superior metal chelating and cation exchange properties were verified.Using its multifunctional properties,the adsorbent was applied to the treatment of anionic dye methyl orange（MO）wastewater and cationic dye crystalline violet（CV）wastewater,respectively.In the treatment of anionic dye MO wastewater,three ammonia-carboxylate adsorbents were not effective in adsorbing MO from monolithic wastewater due to the presence of electrostatic repulsion;while in the MO-Cu²⁺binary system,three adsorbents could adsorb MO-Cu²⁺complexes by metal chelation,among which the pentadentate ligand IDS functionalized silica adsorbent with moderate coordination atoms was the most effective.It proved the correctness of the idea that anionic dyes and metal ions can be removed simultaneously as a whole.In the treatment of cationic dye CV wastewater,EDDS-Silica showed superior treatment effect compared with other ammonia carboxylate adsorbents,and the saturation adsorption capacity of EDDS-Silica on CV could reach 289 mg/g under the optimal adsorption conditions.The thermodynamic study results showed that the adsorption process was consistent with the Langmuir isothermal adsorption model,and the thermodynamic parameters:indicated The adsorption process is a spontaneous reaction with heat absorption and increasing confusion at the solid-liquid interface;the adsorption of CV by EDDS-Silica is mainly through the electrostatic and hydrogen bonding between the two.In addition,the adsorbent has good regenerative properties,indicating that EDDS-Silica is an economically feasible and environmentally friendly adsorbent.In this study,a multifunctional ammonia-carboxylate silica gel adsorbent was produced for the treatment of dye wastewater with complex composition,and it was demonstrated that this type of adsorbent could be used for the treatment of both anionic and cationic pollutants;meanwhile,this study provided a selection law of ammonia-carboxylate ligands for the treatment of different wastewaters.