Sorption of Halogenated Anti-Inflammatory Pharmaceuticals from Polluted Aqueous Streams on Activated Carbon: Lifetime Extension of Sorbent Caused by Benzalkonium Chloride Action

Abstract

The enhancement of the adsorption capacity of activated carbon (AC) using benzalkonium chloride (BAC) within the adsorption of halogenated pharmaceuticals flufenamic acid (flufa) and diclofenac (dcf) was investigated in this study. An adsorption kinetic study was performed to evaluate the adsorption mechanisms. The adsorption mechanism of both drugs on granulated AC as well as saturated AC activated by BAC can be evaluated via pseudo-second kinetic order. The equilibrium adsorption capacity of spent granulated AC in co-action with BAC (qflufa = 195.5 mg g−1 and qdcf = 199.5 mg g−1) reached the adsorption capacity of virgin granulated AC (qflufa = 203.9 mg g−1 and qdcf = 200.7 mg g−1). Finally, batch and column arrangements were compared in an effort to possible practical application of exhausted AC in co-action with BAC. In both column and batch experiments, adsorption capacities of spent granulated AC for flufa increased using BAC by 170.4 mg g−1 and 560.4 mg g−1, respectively. The proposed mechanism of adsorption enhancement is the formation of less polar ion pairs and its better affinity to the non-polar AC surface. The drug concentrations were determined using the voltammetric method on carbon paste electrodes. The formation of ion pairs has been studied by the H1 NMR technique, and solubility in water of drugs and respective ion pairs were investigated using octan-1-ol/water coefficients (POW).

Co-Action of Ionic Liquids with Alternative Sorbents for Removal of Reactive Azo Dyes from Polluted Wastewater Streams

“…The better separation of RB8 using BAC can be caused by the better solubility of BAC in water and thus a better contact of BAC and RB8 dissolved in water. Based on these findings, BAC combines both sufficient aqueous solubility and the removal efficiency of acid halogenated pollutants such as RB8 dye; for more information, see our previous studies [32,44,45].…”

“…Our previous works [32,44,45] reported that the addition of appropriate amounts of quaternary ammonium compounds (R 4 NX, ILs) to the aqueous solutions of acidic halogenated compounds (substituted with -COO − or -SO 3 − groups), including dyes or drugs, results in ion exchange and the formation of respective insoluble ion pairs (see Equation ( 1) above and Scheme 1 below) that can be separated from aqueous solutions by simple filtration. The formation of the mentioned ion pairs has been earlier proven by NMR analysis; see refs.…”

“…The formation of the mentioned ion pairs has been earlier proven by NMR analysis; see refs. [32,44,45]. Therefore, the subsequent experiments were focused on the separation of RB8 dye using two ILs-BAC [52] and A336 [53] (for chemical drawings, see Figure 2 above).…”

“…The authors [27,33,36] reported an improvement in the sorption capacity of these sorbents via impregnation prior to adsorption. However, we have earlier [32,44] discovered the simple and technologically undemanding method of the co-action of carbonaceous sorbents with ILs for the effective separation of halogenated organic acids from aqueous solutions. The RB8 separation cycle layout using the co-action of alternative sorbents with benzalkonium chloride is illustrated and presented in Scheme S1 and Figure S3 in the Supplementary Materials.…”

“…As we previously published, anionic drugs [44] or anionic azo dyes [45] can be effectively separated from aqueous solutions using ILs based on quaternary ammonium salts (R 4 NX). This method consists in the addition of commercially available and inexpensive ILs, which is accompanied by the ion exchange of inorganic anions X − of R 4 NX with anions of acid dyes (according to Equation ( 1)), producing low-polar ion pairs (dye-SO 3 NR 4 ) insoluble in aqueous solution and separable by sedimentation and/or filtration.…”