In the last few decades, pharmaceuticals, credited with saving millions of lives, have emerged as a new class of environmental contaminant. These compounds can have both chronic and acute harmful effects on natural flora and fauna. The presence of pharmaceutical contaminants in ground waters, surface waters (lakes, rivers, and streams), sea water, wastewater treatment plants (influents and effluents), soils, and sludges has been well doccumented. A range of methods including oxidation, photolysis, UV-degradation, nanofiltration, reverse osmosis, and adsorption has been used for their remediation from aqueous systems. Many methods have been commercially limited by toxic sludge generation, incomplete removal, high capital and operating costs, and the need for skilled operating and maintenance personnel. Adsorption technologies are a low-cost alternative, easily used in developing countries where there is a dearth of advanced technologies, skilled personnel, and available capital, and adsorption appears to be the most broadly feasible pharmaceutical removal method. Adsorption remediation methods are easily integrated with wastewater treatment plants (WWTPs). Herein, we have reviewed the literature (1990-2018) illustrating the rising environmental pharmaceutical contamination concerns as well as remediation efforts emphasizing adsorption.

Pharmaceuticals of Emerging Concern in Aquatic Systems: Chemistry, Occurrence, Effects, and Removal Methods.

Modification of biochar derived from sawdust and its application in removal of tetracycline and copper from aqueous solution: Adsorption mechanism and modelling

Effect of Cu(II) ions on the enhancement of tetracycline adsorption by Fe3O4@SiO2-Chitosan/graphene oxide nanocomposite

Novel insight into adsorption and co-adsorption of heavy metal ions and an organic pollutant by magnetic graphene nanomaterials in water

ZIF-8 nanoparticles were prepared with a convenient method at room temperature. The morphology and components of the ZIF-8 were characterized by scanning electron microscopy (SEM), powder X-ray diffraction spectroscopy (PXRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR) and zeta potential analysis. The ZIF-8 nanoparticles were relatively stable under neutral and alkaline solutions, while their structure easily collapsed partially in the strong acidic aqueous solution. The adsorption kinetics and isotherms of ZIF-8 for tetracycline were evaluated in detail. The effects of key parameters such as pH, contact time, temperature and ionic strength on the adsorption of tetracycline were studied. The data on the adsorption of tetracycline on the ZIF-8 nanoparticles fitted well to the pseudo-second-order kinetics model, while the adsorption isotherm data can be explained respectively by the Langmuir isothermal model and the Freundlich isotherm model to varying degrees. The equilibrium quantity of tetracycline on ZIF-8 obtained in adsorption kinetic studies was 124.6 mg g−1 at 25 °C, while the value calculated by the Langmuir isotherm model was above 1000 mg g−1 at the same temperature. This implied that the adsorption capacity of ZIF-8 to tetracycline can be improved to a large extent. The analysis of the adsorption mechanism showed that electrostatic attraction and π–π stacking interaction both played crucial roles in the adsorption process. Regeneration experiments indicated that the used adsorbent still showed excellent applicability after four rounds of recycling.

Zeolitic imidazolate metal organic framework ZIF-8 with ultra-high adsorption capacity bound tetracycline in aqueous solution

Preparation of amino-Fe(III) functionalized mesoporous silica for synergistic adsorption of tetracycline and copper

Removal of tetracycline antibiotics from aqueous solution by amino-Fe (III) functionalized SBA15

Fe-incorporated SBA15 (Fe-SBA15) with different contents of Fe(III) was synthesized in order to enhance the adsorption of antibiotic tetracycline (TC) from aqueous solution. The influence of the Fe(III) content on the structural, textural and morphological properties of the adsorbents and the adsorption process of TC were investigated. The results showed that the adsorbents exhibited mesoporous structural order after co-condensation with different ratios of Fe/Si. As the Fe/Si ratio increased from 0.02 to 0.1, the Fe(III) incorporated into the mesoporous silica framework offered abundant active sites for the adsorption of TC. The adsorption behavior was systematically studied and the results showed that Fe-SBA15 had higher adsorption capacity for TC than that of SBA15. The optimized solution pH for the adsorption was around 5.0 to 7.0, and the adsorption was endothermic and spontaneous. The adsorption mechanism mainly involved inner-sphere surface complexes formed between functional groups of TC and the Fe(III) on the adsorbent. The synthesized materials have excellent potential as adsorbents for environmental remediation.

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Iron-incorporated mesoporous silica for enhanced adsorption of tetracycline in aqueous solution

Currently, inner-generate hydrogen peroxide to enhance the degradation of pollutants is an outstanding way. However, few studies have been done on MoS2 photocatalysts with sulfur vacancies at the phase-junction to produce innergenerate-H2O2 to promote contaminants degradation. Herein, we prepared Mo1−xS2−y photocatalysts with sulfur vacancies at the phase-junction by a simple method (temperature-programmed reduction in hydrogen atmosphere) to achieve high innergenerate-H2O2 and high degradation efficiency. Specifically, Mo1−xS2−y exhibited a high yield of innergenerate-H2O2 (35 μmol L−1 h−1, 1.5 times as high as bulk MoS2) under simulated solar irradiation, because the promoted electron transfer can increase superoxide radical to generate innergenerate-H2O2. Hydroxyl radicals generated by decomposition of innergenerate-H2O2 through the transformation of variable metal molybdenum atom (Mo(Ⅳ)/Mo(Ⅵ)) can effectively improve the degradation efficiency of tetracycline and diclofenac sodium (twice as high as bulk MoS2). The novel and concise way was paved to synthesize photocatalysts for high-efficiency photocatalytic degradation by innergenerate-H2O2. 

Ziyang Zhang

Papers

Preparation of amino-Fe(III) functionalized mesoporous silica for synergistic adsorption of tetracycline and copper

Removal of tetracycline antibiotics from aqueous solution by amino-Fe (III) functionalized SBA15

Iron-incorporated mesoporous silica for enhanced adsorption of tetracycline in aqueous solution

Efficient degradation of PPCPs by Mo1-xS2-y with S vacancy at phase-junction: promoted by innergenerate-H2O2

Manipulate organic crystal morphology and charge transport