Adsorption Of Tetracycline Hydrochloride Research Articles

Effect of calcination temperature on the presence pattern of calcium ions in slag-based geopolymer microspheres and visible light photocatalytic degradation of tetracycline hydrochloride

Tetracycline hydrochloride (TC) is currently treated mostly with photocatalysts that the preparation process is complicated and costly, limiting its large-scale application. In this study, slag-based geopolymer microspheres (SGMs) photocatalysts were prepared from low-cost slag as raw material using geopolymer technology, and excellent visible-light degradation properties for TC could be obtained by simple calcination. When the water addition was 4 g, the stirring speed was 1000 rpm and the calcination temperature was 800 °C for 3 h, the initial pH was 4.72 and the photocatalyst dosage was 0.4 g/L, SGMs showed excellent photocatalytic performance for TC with 94.76 % degradation in visible-light. Compared with the traditional powder materials, SGMs can achieve rapid separation with excellent settling performance (it can be completely settled within 1 min). With degradation rate remaining over 90 % after five cycles, it showed excellent cyclic stability. The degradation mechanism of SGMs on TC was as follows: firstly, TC adsorption takes place on the SGMs surface during the dark reaction stage; secondly, with Ca2+ in the SGMs enter the solution, it complexed with the TC, making it positively charged and accelerating the generation of free radicals, adsorption and degradation occurred simultaneously, with the order of active free radical action on TC degradation being ·O2- >·OH > h+. The SGMs prepared in this project has the benefits of being inexpensive, easy to operate, environmental protection, excellent visible-light photocatalyst performance, and potential industrial application prospects.

Efficient Adsorption and Degradation of Tetracycline Hydrochloride Using Metal-Organic Framework-Derived Cobalt-Based Catalysts and Mechanism Insight.

High-performance Co-based catalysts were derived by pyrolysis using synthesized MOFs as self-sacrificial templates. Various catalytic systems were constructed by peroxymonosulfate (PMS) to degrade tetracycline hydrochloride (TC). Adsorption-degradation efficiencies, cycle performance, dynamics, and the adsorption catalytic mechanism of various catalytic systems for TC were studied. The effects of different synthetic solvents, pyrolysis temperatures, and single/bimetallic element compositions on degradation efficiency were innovatively compared. The optimal catalyst and PMS dosage for the experiment were determined to be 10 mg and 0.1 mL, respectively. The results indicated that all catalytic systems could efficiently degrade TC and have a high acid-base resistance. The catalyst activity was significantly influenced by the pyrolysis temperature. The optimum pyrolysis temperatures for Zn@Co-N-C-T, CH3OH@Co-N-C-T, and H2O@Co-N-C-T were 1000, 900 and 900 °C, respectively. More abundant pore structures and active sites were generated in Zn@Co-N-C-1000, exhibiting an excellent TC degradation efficiency and adsorption capacity, achieving 94.73% and 167.564 mg/g, respectively. Meanwhile, the total organic carbon (TOC) of TC (50 mL, 50 mg/L) achieved a removal rate (TOC/TOC0) of 50.28%. Zn@Co-N-C-1000/PMS maintained over 83.27% TC degradation after five cycles. The adsorption mechanism of the catalyst for TC was investigated through the analysis of adsorption kinetics and isotherm models. The quenching test and EPR results indicated that TC was primarily degraded through the nonradical pathway. The efficient degradation of TC is attributed to the rapid electron transfer processes occurring at the two-phase interface and the redox cycling of Co0/Co2+/Co3+. Finally, LC-MS was used to analyze the intermediate products of TC degradation in the Zn@Co-N-C-1000/PMS system, and two degradation pathways were proposed.

Facile Fabrication of Zeolitic Imidazolate Framework-8@Regenerated Cellulose Nanofibrous Membranes for Effective Adsorption of Tetracycline Hydrochloride.

The excessive utilization of antimicrobials in humans and animals has resulted in considerable environmental contamination, necessitating the development of high-performance antibiotic adsorption media. A significant challenge is the development of composite nanofibrous materials that are both beneficial and easy to fabricate, with the aim of improving adsorption capacity. Herein, a new kind of zeolitic imidazolate framework-8 (ZIF-8)-modified regenerated cellulose nanofibrous membrane (ZIF-8@RC NFM) was designed and fabricated by combining electrospinning and in situ surface modification technologies. Benefiting from its favorable surface wettability, enhanced tensile strength, interconnected porous structure, and relatively large specific surface area, the resulting ZIF-8@RC NFMs exhibit a relatively high adsorption capacity for tetracycline hydrochloride (TCH) of 105 mg g-1 within 3 h. Moreover, a Langmuir isotherm model and a pseudo-second-order model have been demonstrated to be more appropriate for the description of the TCH adsorption process of ZIF-8@RC-3 NFMs. Additionally, this composite fibrous material could keep a relatively stable adsorption capability under various ionic strengths. The successful fabrication of the novel ZIF-8@RC NFMs may shed light on the further development of wastewater adsorption treatment materials.

Seed-assisted two-step ZIF-67 growth on CS/PVA nanofibers for high-efficiency cadmium and tetracycline adsorption

Herein, novel ZIF-67/CS/PVA (CNF-2) nanofiber composites using a two-step seed-assisted in situ electrospinning method, with cobalt-based zeolitic imidazolate framework (ZIF-67) as the precursor was prepared. SEM, EDX, AFM, FTIR, and XRD analyses revealed the optimal formation of ZIF-67 nanoparticles both inside and on the surface of CS/PVA nanofibers without compromising the structure of these electrospun nanofibers. The unique porous structure and heterointerfaces of the ZIF-67/CS/PVA (CNF-2) nanofiber composites demonstrated remarkable adsorption capacities for cadmium (Cd) and tetracycline hydrochloride (TCH), achieving 1137.94 and 1029.5 mg/g, respectively. The adsorption effectiveness for Cd and TCH was 94.83 % and 85.79 %, respectively, under optimal adsorption conditions: pH 8, adsorbent dosage of 0.01 g, initial Cd and TCH concentration of 80 mg/L, and a contact time of 120 min. The study of coexisting Cd and TCH adsorption on CNF-2 under varying pH conditions (4–8) reveals a significant enhancement in Cd adsorption efficiency, increasing from 41.91 % to 97.49 %. Conversely, TCH exhibits a more modest improvement, with its adsorption efficiency rising from 72.53 % to 85.96 %. Kinetic and equilibrium studies revealed that the adsorption followed pseudo-second-order kinetics and the Langmuir isotherm. The prepared nanofiber adsorbed 60 % of Malachite green dye. The engineered adsorbent demonstrated impressive regeneration potential, maintaining its efficiency over three successive adsorption–desorption cycles.

Round-the-Clock Adsorption-Degradation of Tetracycline Hydrochloride by Ag/Ni-TiO2.

The synergy of adsorption and photocatalysis is a good method to remove organic pollutants in wastewater. In recent decades, persistent photocatalysis has gained considerable interest for its ability to sustain the catalytic degradation of organic pollutants in the dark. Herein, we report three different TiO2 nanomaterials to remove tetracycline hydrochloride (TCH) in solution. We found that the removal ability of TiO2, Ni-TiO2, and Ag/Ni-TiO2 is 8.8 mg/g, 13.9 mg/g and 23.4 mg/g, respectively, when the initial concentration of TCH is 50 mg/L. Chemical adsorption could be the rate-determining step in the TCH adsorption process. Moreover, Ag nanoparticles dispersed on Ni doped TiO2 surface act as traps to capture photo-generated electrons upon illumination with indoor light. The holes in Ag/Ni-TiO2 serve as critical oxidative species in TCH degradation under dark conditions. This work provides new insights into the design of persistent photocatalysts that can be activated by weak illumination and degrade organic pollutants in wastewater after sunset.

Magnetic recyclable Co-MOF derivate-modified steel slag for tetracycline removal by integrated adsorption and Fenton-like catalysis

As a category of emerging pollutants, the wide occurrence of antibiotics in water bodies has adverse effects on aquatic organisms. Herein, a Co-MOF derivate-modified magnetic steel slag (MSS@Co-CN) was fabricated and used to remove tetracycline hydrochloride (TCH), a representative antibiotic, from wastewater by the synergistic effect of adsorption and Fenton-like oxidation. MSS@Co-CN exhibited a high adsorption capacity (qmax > 416.6 mg/g) and a strong Fenton-like catalytic oxidation capacity for TCH (80 % removal efficiency within 5 min) by activating peroxymonosulfate (PMS) in a wide pH range (pH = 2–11). The TCH adsorption on MSS@Co-CN, with equilibrium reached within 30 min, was proved to be an exothermic multilayer adsorption process by the Freundlich and Temkin models. It also exhibits excellent stability of catalytic activity in five adsorption-oxidation cycles. The superoxide anion radicals and singlet oxygen were the main active species in the Fenton-like reaction. The concentration of leaching iron ion (0.03 mg/L, far below the standard for surface water) after the reaction was significantly reduced after Co-CN modification. Furthermore, the good magnetic property of MSS@Co-CN makes it easily separatable from water, showing good application potential. This work is expected to provide insight into the fabrication of highly efficient catalysts for antibiotic removal by the synergistic effect of adsorption and Fenton-like catalysis.

Interfacial Si–O–Zr bonds induced well dispersed zirconia on magnetic mesoporous silicas for enhanced tetracycline removal

Constructing recoverable materials with both high adsorption capacity and excellent photocatalytic performance towards antibiotics elimination is very meaningful and challenging in wastewater remediation. In this work, we demonstrate a simple interface engineering strategy to design well dispersed zirconia on core–shell structured magnetic mesoporous silica microspheres (MMS) for efficient removal of tetracycline hydrochloride (TC). With ultrahigh specific surface area (682.0 m2/g) and interfacial Si-O-Zr serving as active sites, the optimal sample (MMS-Zr10) exhibits enhanced TC adsorption capacity of 266.5 mg/ZrO2 g, which is 19.2-fold than that of pure ZrO2. Simultaneously, the photocatalytic degradation rate constant of TC over MMS-Zr10 in the presence of peroxydisulfate (PDS) is 12.5 times that of ZrO2 under visible light irradiation, which may be attributed to the enhanced light harvest capability and high charge separation efficiency facilitated by interfacial Zr–O–Si charge transfer channels. Furthermore, in consecutive adsorption cycles in both deionized (DI) water solution and actual wastewater, no obvious decline in TC removal % is observed. The TC adsorption is mainly governed by pore filling, hydrogen bonding and electrostatic interactions; whilst O2•−, h+, SO4•−, •OH and 1O2 species are responsible for enhanced photocatalytic degradation of TC.

Biochar derivation at low temperature: A novel strategy for harmful resource usage of antibiotic mycelial dreg

Antibiotic mycelial dreg (AMD) has been categorized as hazardous waste due to the high residual hazardous contaminants. Inappropriate management and disposal of AMD can cause potential environmental and ecological risks. In this study, the potential of pleuromutilin mycelial dreg (PMD) as a novel feedstock for preparing tetracycline hydrochloride (TC) adsorbent was explored to achieve safe management of PMD. The results suggested that residual hazardous contaminants were completely eliminated after pyrolysis. With the increase of pyrolysis temperature, the yields, H/C, O/C, (O + N)/C, and pore size in PMD-derived biochars (PMD-BCs) decreased, while BET surface area and pore volume increased, resulting in the higher stability of the PMD-BCs prepared from higher temperatures. The TC adsorption of the PMD-BCs increased from 27.3 to 46.9 mg/g with the increase of the pyrolysis temperature. Surprisingly, pH value had a strong impact on the TC adsorption, the adsorption capacity of BC-450 increased from 6.5 to 71.1 mg/g when the solution pH value increased from 2 to 10. Lewis acid-base interaction, pore filling, π-π interaction, hydrophobic interaction, and charge-assisted hydrogen bond (CAHB) are considered to drive the adsorption. This work provides a novel pathway for the concurrent detoxification and reutilization of AMD.

Adsorption of antibiotics on microplastics (MPs) in aqueous environments: The impacts of aging and biofilms

Microplastics (MPs) that accumulate in natural water bodies through various pathways inevitably undergo aging and biofilm attachment. These variations can alter the physicochemical properties of the MPs and thus affect their abilities to adsorb other pollutants. In this study, we chose virgin polyethylene (V-PE) as the experimental MP and generated aged, biofilm-developed and biofilm-developed with aged polyethylene (A-PE, B-PE and B-A-PE) via Fenton advanced oxidation and lake water incubation methods. Then, the adsorption of tetracycline hydrochloride (TC-HCl) and cefalexin (CFX) on V-PE, A-PE, B-PE and B-A-PE was investigated. The results showed that the capacities for adsorption of TC-HCl or CFX on the four polyethylene MPs (PEMPs) increased in the order V-PE < A-PE < B-PE < B-A-PE. The order was attributed to differences in the surface roughnesses, crystallinities, surface functional groups and biofilm biomass of the four PEMPs. Kinetic experiments and isotherms indicated that nonlinear multilayer adsorption occurred via physicochemical actions, such as diffusion, hydrophobic interactions, hydrogen bonding interactions, electrostatic interactions and biodegradation. Specifically, the adsorption of TC-HCl or CFX by V-PE and A-PE was predominantly controlled by diffusion, whereas B-PE and B-A-PE were chemically active. In addition, it is worth noting that biofilms may shield antibiotics from electrostatic interactions with the B-PE and B-A-PE surfaces, and an increase in ionic strength inhibited the adsorption of TC-HCl and CFX by the four PEMPs. Our study provides an important reference for determining the adsorption of antibiotics by MPs in natural waters.

Alleviating effects of microplastics together with tetracycline hydrochloride on the physiological stress of Closterium sp.

Microplastics have significant influence on both freshwater cyanobacteria and marine microalgae, especially under co-exposure with other pollutants such as heavy metals, antibiotics, and pharmaceuticals. In the present study, combined effects of microplastics (polyethylene terephthalate (PET) or polybutylene terephthalate (PBT)) and tetracycline hydrochloride (TCH) on the microalgae Closterium sp. were studied to evaluate their acute toxicity, and the cell density, total chlorophyll concentration, photosynthetic activity, antioxidant system, and subcellular structure of Closterium sp. under different treatments were used to explain the physiological stress mechanism of the combined effects. The results indicate that both the single and combined treatments have inhibition effects on the cell growth and photosynthetic activity, with inhibition efficiencies (in terms of cell density) of 5.0%, 9.2%, 66.7%, 55.1%, and 59.8% for PET (100 mg L-1), PBT (100 mg L-1), TCH (10 mg L-1), PET/TCH (PET 100 mg L-1 and TCH 10 mg L-1), and PBT/TCH (PBT 100 mg L-1 and TCH 10 mg L-1), respectively, and relative electron-transport rates (rETRs) of 7.3%, 12.7%, 66.8%, 54.0%, and 59.9%, respectively, for each treatment compared with the control on the 7th day. Moreover, both PET and PBT have positive effects in alleviating TCH toxicity toward Closterium sp., and at the same time, the malondialdehyde level (MDA), superoxide dismutase (SOD) activity, and catalase (CAT) activity induced by the combined treatments were much higher than those from the single microplastic treatments but lower than those from TCH treatment after 7 days. It was demonstrated that TCH causes a much more serious oxidative stress than PET/TCH and PBT/TCH, and the lower oxidative stress of the PET/TCH and PBT/TCH groups could be attributed to the adsorption of TCH to PET or PBT. This work improves the understanding of the combined toxicity effects of microplastics and TCH on Closterium sp.

Functionalized magnetic chitosan-based adsorbent for efficient tetracycline removal: Deep investigation of adsorption behaviors and mechanisms

As removal performance of tetracyclines in traditional wastewater treatment plants cannot satisfy the increasingly strict discharge requirements, developing an efficient approach to overcome this problem is quite urgent. Herein, a novel functionalized magnetic chitosan-based adsorbent (Fe3O4@CAA) with core-shell structure and unique magnetic responsiveness was facilely prepared by ultrasound-initiated radical grafting copolymerization and cross-link reaction. The as-prepared Fe3O4@CAA was fully characterized with TEM, SEM, BET, FTIR, TGA, XRD, VSM, and served as an efficient adsorbent for tetracycline hydrochloride (TCH) removal. Adsorption behaviors of TCH by Fe3O4@CAA were deeply evaluated at different adsorption time, initial TCH concentration, reaction temperature, solution pH, and background pollutant concentration. Results showed that Fe3O4@CAA presented a more competitive adsorption capacity of 325.04 mg g−1 compared with Fe3O4@CS and other reported adsorbent, due to the introduction of more active adsorption sites by abundant functional groups, including amino groups, hydroxyl groups, and sulfonic acid groups. After saturated adsorption, TCH loaded Fe3O4@CAA was easily collected by magnetic separation, and recycled after acid pickling. Fe3O4@CAA was successfully reused in five adsorption-desorption cycles, without obvious adsorption capacity loss. In binary pollutant systems, inorganic cations and Pb(II) restrained TCH adsorption by competitive effect, while proper amount of Cu(II) promoted TCH adsorption by bridge effect. FTIR and XPS analyses revealed that the adsorption mechanism of TCH by Fe3O4@CAA mainly included electrostatic interaction and hydrogen bonding, and Cu(II) could play a “mediator” role to form a strong Cu(II)-TCH complex to enhance TCH removal performance. This study provides an effective strategy for the design of magnetic chitosan-based adsorbents and valuable guidance for the removal of tetracyclines from wastewater.

Comparison studies: The aging character of mask melt blown layers, polypropylene, and polyethylene terephthalate and their adsorption behavior for tetracycline hydrochloride

Melt-blown layer as a crucial component in medical surgical masks could release microplastics (MPs) into the environment after discarding. This study investigated the aging characteristics of the mask melt-blown layer, polypropylene (PP) and polyethene terephthalate (PET) MPs, as well as compared the adsorption capacity of tetracycline hydrochloride (TCH) on the virgin and aged MPs to gain adsorption mechanism. The carbonyl index (CI) index and two-dimensional correlation spectroscopy (2D-COS) analysis showed that the melt blown layer had the lower degree of aging than PP. Compared with the virgin PP and PET, the main reason for the lowest adsorption capacity of TCH on the virgin melt blown layer was that its unique dense microchannel structure led to the strongest hydrophobicity. The virgin PP and PET which had different chemical structures exhibited similar adsorption capacity of TCH. The adsorption of TCH on the MPs was physisorption, which was both controlled by diffusion, partitioning interaction and pore filling. The increase in the adsorption capacity of TCH on the aging MPs was attributed to the increase of hydrophilicity, pore size and specific surface area. In addition, the influence of environmental factors on the adsorption of TCH were discussed. Allover, this research provided comprehensive insights into the enrichment behavior associated with mask melt-blown materials in aquatic environments, and offered valuable data to support the investigation of the desorption behavior between MPs and antibiotics on organisms.

Fabrication of Iron-Containing Biochar by One-Step Ball Milling for Cr(VI) and Tetracycline Removal from Wastewater.

Simple ball milling technology can simultaneously improve the adsorption performance of adsorbents for heavy metals and organic pollutants and has attracted increasing attention. Iron-modified biochar (Fe@MBC) was prepared by one-step ball milling, and the characterization results proved that FeCl3 was successfully loaded on biochar. The removal rates of Cr(VI) and tetracycline hydrochloride (TC) by Fe@MBC were increased by 88.27% and 82.64% compared with BC. The average pore size, oxygen-containing functional groups and graphitization degree of Fe@MBC are higher than those of BC, which is more conducive to promoting adsorption. The adsorption isotherms show that the adsorption of Cr(VI) and TC on the Fe@MBC surface conforms to the Langmuir type of single-layer adsorption and the Freundlich model of multilayer adsorption, respectively. The maximum adsorption capacities of Cr(VI) and TC are 25.46 and 66.91 mg·g-1, respectively. Kinetic experiments show that the adsorption process is more consistent with the pseudo-second-order model of chemical adsorption. The adsorption process of Cr(VI) and TC on the Fe@MBC surface is a spontaneous endothermic process that becomes more obvious as the temperature increases. The increase in solution pH has a significant impact on the removal rate of Fe@MBC. When the pH value increased from 3 to 11, the adsorption rates decreased by 53.74% and 17.16%, respectively. The presence of PO43-, CO32-, K+, and Cu2+ significantly affects the adsorption of TC by Fe@MBC, and PO43- and CO32- also affect the adsorption of Cr(VI). Mechanistic studies show that ion exchange, electrostatic interaction, pore filling, and hydrogen bonding contribute to the removal of Cr(VI) and TC by Fe@MBC. The removal mechanism of Cr(VI) also involves complexation and redox reactions, and the removal mechanism of TC involves π-π bonds and van der Waals forces. The results show that Fe@MBC is a green and efficient adsorbent.

Tailored design of hierarchically porous metal/N-codoped carbon from soft-templated bimetallic ZIFs for the high-efficiency adsorption of tetracycline hydrochloride

Zeolitic imidazolate framework-8 (ZIF-8) is attracting considerable attention as a superior precursor to fabricate efficient carbon-based absorbents for many contaminants. However, most carbon materials still suffer from low-efficiency mass transfer and few active sites. Herein, transition metal/nitrogen-codoped hierarchically porous carbons (MNHCs) were controllably constructed by pyrolysis of soft-templated bimetallic ZIFs to enhance tetracycline hydrochloride (TCH) adsorption. Benefitting from its large specific surface area (920.73 m2 g−1), excellent hierarchical pore structure, high N content and abundant Lewis acid sites, the optimum MNHC (HC1000-Fe2Zn98) obtained at 1000 ℃ and the Fe/(Fe + Zn) molar ratio of 2 % improved the adsorption affinity for TCH and reduced the TCH diffusion resistance compared with other MNHCs, resulting in excellent adsorption of TCH. The synergistic effect of Fe and soft templates (sodium dodecyl benzene sulfonate, SDBS) added to the precursor significantly improved pore structure and enriched adsorption active sites of the derived carbon. The adsorption kinetics and isotherm data fitted well with pseudo-second-order kinetics and the Sips model (qm = 245.6 mg g−1), respectively. Adsorption experiments and characterization analyses suggested various adsorption interactions between TCH and MNHCs via pore fillings, coordination, H-bonding and π-π interactions. This study offers a facile strategy for fabricating hierarchically porous carbon for removing organic contaminants from water.

Montmorillonite-modified stabilizing SA/CMC gel spheres cross-linked by lanthanum for tetracycline hydrochloride removal

In this study, a stable gel sphere was successfully prepared by crosslinking sodium alginate(SA) with sodium carboxymethyl cellulose(CMC) through La and modified by MMT for removing tetracycline hydrochloride (TCH). The obtained materials have been comprehensively characterized using SEM, FTIR, XRD and XPS. The results of batch experiments showed that La@SA/CMC-MMT-0.5 had a high adsorption capacity of TCH, and its maximum adsorption capacity was up to 420.95 mg/g. The adsorption process followed a pseudo-second-order kinetic model and the Freundlich isotherm model. The removal of TCH was a combined process involving both chemisorption and physical adsorption. Hydrogen-bond and complexation played a primary role in removing process, while the role of static electricity was more limited. The MMT modification not only enhanced adsorption capacity of TCH but also improved the thermal stability of the material by creating a temperature barrier and promoting hydrogen-bond. La substitution of metal ions in MMT and electrostatic attraction by MMT-surface negative charges contributed to reducing La-release. In application experiments, the La@SA/CMC-MMT-0.5 showed a high adsorption capacity, strong anti-disturbance performance, and good reusability. Therefore, La@SA/CMC-MMT-0.5 holds great potential for the effective adsorption of TCH in aqueous environments.

Structural design of core-shell ZIF-8@NH2-MIL-125 photocatalyst for synergistic adsorption-photocatalytic degradation of tetracycline hydrochloride

The development of a green, efficient, and reusable photocatalyst is of great importance for pollution remediation. Herein, a series of core-shell ZIF-8@NH2-MIL-125 composites (ZM-X) were prepared by epitaxial growth method. The in-situ homogeneous encapsulation of NH2-MIL-125 by ZIF-8 was achieved through the structural modulation, and the formed core-shell architecture exhibited outstanding synergistic effect of adsorption and photocatalysis for eliminating tetracycline hydrochloride (TCH), which dramatically enhanced the photocatalytic reaction rate. The results show that the TCH adsorption capacity of optimized ZIF-8@NH2-MIL-125 (ZM-2) is 70.25mgg–1, which can be fitted well the pseudo-second-order and Langmuir isotherm modes. Under 100min of visible light irradiation, the ZM-2 has the best synergistic removal rate on TCH (92.9%) compared with other samples, which is 6.5 times higher than of pristine NH2-MIL-125 (14.3%). The results of quenching experiments and ESR analysis clearly demonstrate that the superoxide radical (·O2–) dominates the TCH photodegradation reaction. In addition, ZM-2 can effectively remove TCH in different types of water systems (e.g., ultrapure water, tap water, lake water and actual pharmaceutical wastewater) through adsorption-photocatalytic synergy. Therefore, the novel core-shell material designed in this study has significant potential for environmental purification applications.

Nonthermal plasma induced NiS/UiO-66-NH2 for boosting visible-light photo-Fenton degradation of tetracycline hydrochloride

Heterojunctions constructed from metal organic frameworks (MOF) and metal sulfides are the potential candidates for solar-light driven photo-Fenton elimination of antibiotics from wastewater. To boost the solar-light induced photo-Fenton degradation of tetracycline hydrochloride (TCH) over UiO-66, NH2-functionlized UiO-66 (UiO-66-NH2) was in-situ loaded with NiS (NiS/NU-66) via the nonthermal plasma sulfurization. For comparison to UiO-66-NH2, NiS/NU-66 had the lower adsorption capacity while the higher photo-Fenton activity for TCH removal. The removal efficiency of NiS/NU-66 climbed and then declined with an increase in NiS content, and the best removal efficiency (84.92 ± 2.55 %) for 110 mg L−1 TCH solution was obtained by c-NiS/NU-66 in 150 min. The sulfur and oxygen defects as well as the plentiful functional groups over NiS/NU-66 were favorable for providing the abundant vacant sites of TCH adsorption and photons capture. In addition, the rapid separation and migration of photo-generated e−/h+ pairs were achieved at the tight junction interface between NiS and UiO-66-NH2, enlarging the visible-light absorption capacity. In NiS/NU-66-assisted photocatalytic system, H2O2 was efficiently convert to •OH by e− and Ni2+/Ni3+ couples in solar light region. Hence, •OH, •O2− and h+ played the vital roles in this photo-Fenton system.

Removal performance and mechanism of tetracycline hydrochloride in aqueous by geopolymers from tourmaline tailings

Tetracycline hydrochloride (TCH) is one of the widespread pollutants in wastewater, which easily causes severe threat to human health and ecological environment. Geopolymers (GPs) have demonstrated potential applications as adsorbents for effluent treatment. Herein, a research on the removal performance and mechanism of TCH by geopolymers from tourmaline tailings (TMT) was introduced. The TMT exhibited the typical characteristics of the amorphous state of geopolymer gel to varying degrees under a series of alkali activator modulus, and the sample with a modulus of 1.2 had the highest average pore diameter and specific surface area, which were 5.83 nm and 150.17 m2·g−1, respectively. The kinetic data were well fitted by pseudo-second-order kinetic model for the adsorption process of TCH on TMT-GP1.2, and the maximum theoretical adsorption capacity, obtained from the Langmuir model, was 105.4 mg·g−1 at 318 K and pH= 5. Thermodynamics indicated that the adsorption process of TCH on TMT-GP1.2 was not only endothermic, but also feasible and spontaneous. The adsorption of TCH by TMT-GP1.2 involved the combined effect of physical and chemical adsorption, including pore filling, electrostatic attraction, hydrogen bonding and ion exchange interactions. Notably, TMT-GP1.2 might show the superposition of excellent functions from the geopolymers and schorl, especially in ion exchange and electrostatic attraction, thus enhancing the removal efficiency of TCH. The adsorption capacity of the TMT-GP1.2 for TCH reached 46.64 mg·g−1 after 5 cycles. Based on the price-effectiveness, effective removal capacity and acceptable reusability, the tourmaline tailings geopolymers were expected to be potential environmentally friendly TCH adsorbents.

Insight and mechanisms of tetracycline adsorption on sodium alginate/montmorillonite composite beads

The presence of antibiotics in soil and water raises great health concerns because they may increase the development of harmful antibiotic-resistant bacteria. In this study, composite beads prepared from 2:1 or 1:1 ratios of montmorillonite (Mt) and sodium alginate (SA) were used to adsorb tetracycline hydrochloride (TC), an antibiotic commonly found in aqueous systems. The equilibrium time for TC adsorption onto the Mt/SA was 8 h, and the kinetic data were consistent with the pseudo-second-order model. The adsorption isotherm was described with the Langmuir equation. The maximum amounts of TC adsorbed were 745, 689, and 445 mg g−1 for the 2:1- and 1:1-Mt/SA and the original Mt, respectively. The Mt/SA composite beads exhibited porous structures; however, this did not play a key role in TC removal, as previously reported. Cation exchange was the major adsorption mechanism, and electrostatic attraction and hydrogen bonding between the SA and TC also contributed to TC adsorption on the Mt/SA composite beads. In addition, the migration of a small amount of TC into the inner spaces of the beads led to the intercalation of the TC in the Mt interlayers and enhanced TC adsorption by the Mt/SA composite beads.

Efficient adsorption of tetracycline hydrochloride on biochar-ceramsite composite: Optimization of response surface methodology and investigation of adsorption mechanism

In this study, to improve the adsorption performance and recovery of biochar in tetracycline hydrochloride (TCH) adsorption, a new biochar adsorbent, biochar-ceramsite composites (OBCC), were prepared by one-step synthesis using response surface methodology to optimize the preparation conditions. The error between the predicted adsorption capacity and the actual tested adsorption capacity was only 1.9% for the optimal preparation conditions. The maximum adsorption capacity (obtained by the Langmuir model) of TCH onto OBCC (30.72 mg/g) is 1.5 times that of ceramsite (CS, 20.86 mg/g) and 1.9 times that of the raw biochar (RBC, 16.47 mg/g). The better adsorption performance of OBCC can be mainly attributed to its more mesopores distribution (average pore size is 14.58 nm) and larger surface area (1.4 and 4.8 times higher than that of CS and RBC, respectively). The TCH adsorption mechanism by OBCC involves various interactions and mechanisms, including electrostatic interactions, π-π interactions and hydrogen bonding. OBCC is non-toxic, easy to solid-liquid separation, and can be potentially reused for 22 times before completely losing its activity, exhibiting great potential to antibiotic elimination.