Adsorption of oxytetracycline on kaolinite

Impact of seawater temperature and physical-chemical properties on sorption of pharmaceuticals, stimulants, and biocides to marine particles

Pharmaceuticals, stimulants, and biocides enter the environment via wastewater from urban, domestic, and industrial areas, in addition to sewage, aquaculture and agriculture runoff. While some of these compounds are easily degradable in environmental conditions, others are more persistent, meaning they are less easily degraded and can stay in the environment for long periods of time. By exploring the adsorptive properties of a wide range of pharmaceuticals, stimulants, and biocides onto particles relevant for marine conditions, we can better understand their environmental behaviour and transport potential. Here, the sorption of 27 such compounds to inorganic (kaolin) and biotic (the microalgae Cryptomonas baltica) marine particles was investigated. Only two compounds sorbed to microalgae, while 23 sorbed to kaolin. The sorption mechanisms between select pharmaceuticals and stimulants and kaolin was assessed through exploring adsorption kinetics (caffeine, ciprofloxacin, citalopram, fluoxetine, and oxolinic acid) and isotherms (ciprofloxacin, citalopram, and fluoxetine). Temperature was shown to have a significant impact on partitioning, and the impact was more pronounced closer to maximum sorption capacity for the individual compounds.

Adsorptive removal of oxytetracycline hydrochloride using bagasse-based biochar powder and beads

Oxytetracycline Hydrochloride (OTC), a common antibiotic used to treat specific illnesses in humans and animals, is characterized by poor absorption into cells, low volatility, and high hydrophilicity. It is a potent contaminant that poses a serious threat to the ecosystem, particularly the aquatic sources. Adsorption onto natural adsorbents is one of the most successful, economical, and ecologically friendly ways to remove antibiotics from waste water. The present work focuses on the adsorption of OTC utilizing alginate biochar beads (AlBCB) and biochar powder (BC) derived from bagasse. The influence of several factors were studies and optimized through batch studies employing BC and AlBCB. After 50 min BC displayed a removal of 97%, at an initial concentration of 10 ppm. The experimental data was discovered to follow PFO kinetics and fit with the Freundlich isotherm adsorption model. AlBCB, after a contact time of 40 min, indicated a maximum percentage removal of 86% for initial concentration of 10 ppm OTC. Al-biochar beads showed the maximum percentage removal at pH 10. 0.5 g of adsorbent was used to carry out all batch experiments at room temperature. The adsorption fitted Freundlich adsorption isotherm and intraparticle diffusion kinetics.

Self-Assembled Aminated and TEMPO Cellulose Nanofibers (Am/TEMPO-CNF) Aerogel for Adsorptive Removal of Oxytetracycline and Chloramphenicol Antibiotics from Water

Antibiotics are used for the well-being of human beings and other animals. Detectable levels of antibiotics can be found in pharmaceutical, municipal, and animal effluents. Therefore, the treatment of antibiotic contaminated water is of great concern. In this study, we fabricated a sustainable aminated/TEMPO cellulose nanofiber (Am/TEMPO-CNF) aerogel to remove oxytetracycline (OTC) and chloramphenicol (CAP) from synthetic wastewater. The prepared aerogel was characterized using different analytical techniques such as elemental analysis, FTIR, TGA, SEM-EDS, and N2 adsorption-desorption isotherms. The characterization techniques confirmed the presence and interaction of quaternary amine -[NR3]+ and -COOH groups on Am/TEMPO-CNF with OTC and CAP, which validates the successful modification of Am/TEMPO-CNF. The adsorption process of the pollutants was examined as a function of solution pH, concentrations, reaction time, and temperatures. The maximum adsorption capacity was 153.13 and 150.15 mg/g for OTC and CAP, respectively. The pseudo-second order (PSO-2) was well fitted to both OTC and CAP, confirming the removal is via chemisorption. Hydrogen bonding and electrostatic attraction have been postulated as key factors in facilitating OTC and CAP adsorption according to spectroscopic studies. Energetically, the adsorption was spontaneous and endothermic for both pollutants. In conclusion, the efficient removal rate and excellent reusability of Am/TEMPO-CNF indicate the strong potential of the adsorbent for antibiotics' removal.

Appraising efficacy of existing and advanced technologies for the remediation of beta-blockers from wastewater: A review

The discharge of emerging pollutants, such as beta-blockers (BB), has been recognized as one of the major threats to the environment due to the ecotoxicity associated with these emerging pollutants. The BB are prescribed to treat high blood pressure and cardiovascular diseases; however, even at lower concentration, these pollutants can pose eco-toxic impacts towards aquatic organisms. Additionally, owing to their recalcitrant nature, BB are not effectively removed through conventional technologies, such as activated sludge process, trickling filter and moving bed bioreactor; thus, it is essential to understand the degradation mechanism of BB in established as well as embryonic technologies, like adsorption, electro-oxidation, Fenton process, ultraviolet-based advance oxidation process, ozonation, membrane systems, wetlands and algal treatment. In this regard, this review articulates the recalcitrant nature of BB and their associated removal technologies. Moreover, the major advantages and limitations of these BB removal technologies along with the recent advancements with regard to the application of innovative materials and strategies have also been elucidated. Therefore, the present review intends to aid the researchers in improving the BB removal efficiency of these technologies, thus alleviating the problem of the release of BB into the environment.

A study on the adsorption property and mechanism of β-cyclodextrin/polyvinyl alcohol/polyacrylic acid hydrogel for ciprofloxacin

Polyvinyl alcohol (PVA), acrylic acid (AA), and β-cyclodextrin (β-CD) were used as monomers, and ammonium persulfate was used as an initiator. Orthogonal tests were optimized the experimental condition, and aqueous polymerization was used to prepare poly-β-cyclodextrin/polyvinyl alcohol/polyacrylic acid (β-CD/PVA/PAA) hydrogel. The samples were characterized by FT-IR (Fourier transform infrared), SEM (Scanning electron microscopy), and XRD (X-ray diffraction). β-CD/PVA/PAA hydrogel was analyzed, which influenced external environmental factors on the β-CD/PVA/PAA hydrogel adsorption performance, and the kinetic behavior of β-CD/PVA/PAA hydrogel on ciprofloxacin (CIP) adsorption was explored. The results concluded that the prepared β-CD/PVA/PAA hydrogel has a well-defined three-dimensional network structure. The decrease in the pH of the CIP solution and the adsorption temperature reduces the adsorption reaction of β-CD/PVA/PAA hydrogel on CIP. The kinetics of CIP adsorption by β-CD/PVA/PAA hydrogel confirmed the pseudo-second-order kinetic model (R 2 > 0.997), the maximum equilibrium adsorption amounts is 372.12 mg/g, the removal rate reaches 74.42%. The adsorption process was mainly chemisorption, the adsorption isotherm fits the Freundlich adsorption isotherm model (R 2 > 0.946), and the adsorption process was heterogeneous with multi-molecular layer adsorption. The adsorption process inclined more toward the adsorption of inhomogeneous multi-molecular layers. The β-CD/PVA/PAA hydrogel retained 80% adsorption properties after three adsorption-desorption under optimal conditions.

The removal performance and mechanisms of tetracycline over Mn-rich limonite

Naturally occurring Mn-rich limonite mainly composed of goethite and manganese oxides was used to remove tetracycline (TC) from the aqueous solution. The effects of dosage, initial solution pH, temperature, and coexisting anions on TC removal were investigated. Results showed that 95% of TC (30.0 mg·L^-1) was removed in a wide pH range of 3.0-9.0 by limonite with high specific surface area (145.0 m²·g^-1) and mesoporous structure. The presence of Cl^-, NO₃^-, and SO₄^2- in the studied concentration range did not influence TC removal efficiency significantly, while PO₄^3- inhibited the adsorption of TC over limonite due to the competition with TC for active sites. Integrated with the FT-IR analysis, electrostatic interaction and complexation were proved to be the adsorption mechanisms of TC by limonite. The quenching experiments and ESR analysis revealed that singlet oxygen (¹O₂) also was involved in TC degradation. In addition, limonite displayed an efficient recycling performance and stability after four cycles. This study revealed that the Mn-rich limonite was a promising adsorbent for TC removal from aqueous solutions and promoted the application of natural mineral material in the environmental field.

Adsorption and detoxification of pharmaceutical compounds from wastewater using nanomaterials: A review on mechanism, kinetics, valorization and circular economy

Antibiotics overuse, inappropriate conduct, and discharge have led to adverse effects on various ecosystems. The occurrence of antibiotics in surface and drinking water is a matter of global concern. It is responsible for multiple disorders, including disruption of endocrine hormones and high chronic toxicity. The hospitals, pharmaceutical industries, households, cattle farms, and aquaculture are the primary discharging sources of antibiotics into the environment. This review provides complete detail on applying different nanomaterials or nanoparticles for the efficient removal of antibiotics from the diverse ecosystem with a broader perspective. Efforts have been made to focus on the degradation pathways and mechanism of antibiotic degradation using nanomaterials. More light has been shed on applying nanostructures in photocatalysis, which would be an economical and efficient solution. The nanoscale material or nanoparticles have incredible potential for mineralizing pharmaceutical compounds in aqueous solutions at low cost, easy handling characteristics, and high efficacy. Furthermore, nanoparticles can absorb the pharmaceutical by-products and wastes at a minimum cost as they can be easily recycled. With the increasing number of research in this direction, the valorization of pharmaceutical wastes and by-products will continue to expand as we progress from old conventional approaches towards nanotechnology. The utilization of nanomaterials in pharmaceutical wastewater remediation is discussed with a major focus on valorization, energy generation, and minimization and its role in the circular economy creating sustainable development.

Facile Fabrication of Flocculent Magnesium Silicate for the Adsorption of Oxytetracycline

The discharge of antibiotics and the potential threat to organisms posed by this have received increasing attention. In this work, flocculent magnesium silicate (FMS) was fabricated by a facile hydrothermal and freeze-drying process, and its adsorption behavior for antibiotic oxytetracycline (OTC) was investigated. FMS presented a sepiolite-type structure and the alkaline solution promoted its hydroxylation. A hierarchical pore structure ranging from micropores to macropores and a high specific surface area of 660 m2/g were exhibited. FMS exhibited a higher adsorption amount in neutral solution than in acidic or alkaline conditions as the physicochemical properties of FMS and OTC were significantly affected by the pH. Adsorption isotherm could be well-described by the Langmuir model, and the calculated saturated adsorption capacity was as high as 265 mg/g. Adsorption kinetics followed the pseudo-second-order kinetic model, and the adsorption rate-controlling step was intraparticle diffusion. Thermodynamic parameters indicated that the adsorption was a spontaneous physicochemical reaction. After five cycles, around 91% of the adsorption performance was still maintained, demonstrating the excellent reusability of FMS. The sepiolite-type FMS fabricated in this work could be applied to remove OTC from wastewater.

Zn/Fe LDH as a clay-like adsorbent for the removal of oxytetracycline from water: combining experimental results and molecular simulations to understand the removal mechanism

Pharmaceuticals are detected at trace levels in water. Their adverse effects on human health and aquatic ecosystems required novel pharmaceutical remediation methods for treating wastewater effluents. Layer double hydroxide (LDH) is abundantly available by simple preparation methods and with low costs. The extensive use of antibiotics nowadays leads to increasing the appearance of antibiotic resistance between bacteria and decreasing the effectiveness of antibiotics. In this work, the removal of one of these antibiotics named "oxytetracycline hydrochloride (OTC)" by Zn/Fe LDH was investigated. The Zn/Fe LDH before and after adsorption was characterized by X-ray diffraction, FT-IR analysis, zeta potential, particle size, BET surface area, HRTEM, FESEM, and XPS. The effects of different factors on the OTC adsorption performance were investigated. The removal percentage of OTC was 77.23% by Zn/Fe LDH. The isothermal and kinetic study of OTC adsorption was carried out at pH 6 at 25 °C using different models. The adsorption mechanism was investigated by Monte Carlo and molecular dynamic simulations.