Utilization of Non-Living Microalgae Biomass from Two Different Strains for the Adsorptive Removal of Diclofenac from Water

Abstract

In the present work, the adsorptive removal of diclofenac from water by biosorption onto non-living microalgae biomass was assessed. Kinetic and equilibrium experiments were carried out using biomass of two different microalgae strains, namely Synechocystis sp. and Scenedesmus sp. Also, for comparison purposes, a commercial activated carbon was used under identical experimental conditions. The kinetics of the diclofenac adsorption fitted the pseudo-second order equation, and the corresponding kinetic constants indicating that adsorption was faster onto microalgae biomass than onto the activated carbon. Regarding the equilibrium results, which mostly fitted the Langmuir isotherm model, these pointed to significant differences between the adsorbent materials. The Langmuir maximum capacity (Qmax) of the activated carbon (232 mg∙g−1) was higher than that of Scenedesmus sp. (28 mg∙g−1) and of Synechocystis sp. (20 mg∙g−1). In any case, the Qmax values determined here were within the values published in the recent scientific literature on the utilization of different adsorbents for the removal of diclofenac from water. Still, Synechocystis sp. showed the largest KL fitted values, which points to the affinity of this strain for diclofenac at relative low equilibrium concentrations in solution. Overall, the results obtained point to the possible utilization of microalgae biomass waste in the treatment of water, namely for the adsorption of pharmaceuticals.

Green Microalgae Scenedesmus Obliquus Utilization for the Adsorptive Removal of Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) from Water Samples

“…In any case, the here obtained Q max is larger than that determined for the adsorption of acetaminophen onto Synechocystis sp. (Q max = 52 mg g −1 ) [41] and quite larger than for the adsorption of diclofenac onto Scenedesmus obliquus biomass (Q max = 28 mg g −1 ) [31]. With respect to other materials used for the biosorption of salicylic acid or ibuprofen from water, Table S2 (Supplementary Information) [32,[61][62][63][64] depicts some recently published Q max and shows that the here determined values for Scenedesmus obliquus biomass are within the range of values in the literature.…”

“…Indeed, undertaking studies on pharmaceuticals removal under realistic conditions, assessing the effect of the pH and of the different components of complex matrices, is necessary. Moreover, different microalgae may have different adsorptive performance [31] so the characterization of biomass from different strains and the utilization of biomasses from assorted microalgae strains for the removal of mixed pharmaceuticals are to be explored. In order to select the most convenient species to be applied in wastewater treatments, information about the release of organic compounds during biosorption by microalgae biomass is essential and should be assessed.…”

“…Indeed, most of the published works in this field are on the uptake of pharmaceuticals by living microalgae [23][24][25]30]. Meanwhile, the employment of non-living microalgae biomass for the adsorptive removal of these pollutants has been barely studied [21,31], with just a few authors addressing the adsorption of NSAIDs [31,32]. This contrasts with the case of other contaminants, such as metals [33,34] or dyes [35,36], for which the good adsorptive performance of microalgae biomass is renowned.…”

“…In this context, the aim of this work was the characterization of Scenedesmus obliquus biomass and the study of its utilization as alternative green adsorbent for the removal of two of the most used NSAIDs, namely, salicylic acid and ibuprofen, from water. Biomass of Scenedesmus obliquus has already been shown to display high adsorption capacity as compared with other strains [31] and, furthermore, this strain is among the most used for wastewater treatment, possesses high growth rates, is capable of growing under a wide range of conditions [44], which motivated its choice for this study.…”

Comparative Thermogravimetric Assessment on the Combustion of Coal, Microalgae Biomass and Their Blend

“…On the other hand, microalgae are efficient microorganisms for wastewater treatment, since they are able to remove not only nutrients, but also heavy metals [11] and emerging contaminants [12,13]. Still, during microalgae cultivation, residual biomass is generated and use should be given to this biomass within the actual circular economy context [14]. Therefore, the utilization of microalgae biomass as a third generation biofuel might be an option for closing the loop and increasing the sustainability of microalgae culture [8].…”