Abstract
In this study, activated carbon (AC) and magnetic activated carbon (MAC) were prepared from Dalbergia sissoo sawdust for the removal of antibiotic Azithromycin (AZM) from aqueous solution. The effect of initial concentration, contact time, pH, adsorbent dosage, and the temperature were investigated for both the adsorbents. The optimum AZM concentration, contact time, pH and adsorbents dosages were found to be 80 mg/L, 120 min, 6 and 7 (pH, respectively, for AC and MAC), and 0.1 g (for both AC and MAC), respectively. The isothermal data of both sets of experiments correlated well with the Langmuir isotherm model, while the kinetic data with the pseudo-second-order model. The adsorption of AZM on both adsorbents was found to be favorable, which is evident in the values of the thermodynamic parameters (ΔH = −26.506 and −24.149 KJ/mol, ΔS = 91.812 and 81.991 J/mol K, respectively, for AC and MAC). To evaluate the effect of AC and MAC on the membrane parameters, a continuous stirred reactor was connected with ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) membranes. High % retention and improved permeate flux (around 90%) were obtained for AC/UF, AC/NF AC/RO, MAC/UF, MAC/NF, and MAC/RO treatments. The percent retention of AZM observed for AC/UF, AC/NF AC/RO was higher than MAC/UF, MAC/NF, and for MAC/RO hybrid processes due to greater surface area of AC than MAC.
Highlights
Two adsorbents, activated carbon (AC) and magnetic activated carbon (MAC), have been developed from the biomass of Dalbergia sissoo in the form of sawdust in an attempt to use this pretreated material for the removal of AZM from aqueous solution, and to control the fouling of membrane caused by the antibiotic AZM
The initial loss is ascribed to the dehydration, the second surface of MAC that has lowered the carbon contents per unit volume compared to that loss to degradation of cellulose and hemi-cellulose, and the third to the formation of AC
On membrane pores and surface, only 11% retention was seen in case of UF membrane, the lower mass of AZM relative to the molecular weight cut-off (MWCO) of UF membrane was suggestive of greater retention
Summary
The light weight of AC and the prolonged duration required for its settling could reduce membrane productivity In these circumstances, magnetic activated carbon (MAC) could be a more suitable pretreatment alternative as, due to its magnetic force and enhanced coagulation properties, it could effectively convert the soluble compounds to coagulated flocs [18,19]. Two adsorbents, AC and MAC, have been developed from the biomass of Dalbergia sissoo in the form of sawdust in an attempt to use this pretreated material for the removal of AZM from aqueous solution, and to control the fouling of membrane caused by the antibiotic AZM
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