Comments and discussion concerning 'Sorption behavior of tebuconazole on microplastics: kinetics, isotherms and influencing factors' [Environ Technol. 2023;44:3937-3948]

The widespread use of synthetic polymers since the mid-twentieth century has led to significant environmental pollution from microplastics (MPs). These MPs, which persist in ecosystems, can interact with various pollutants, including pesticides such as tebuconazole (TEB). The subject paper investigates the sorption behaviour of TEB on different types of MPs (polystyrene, polypropylene, and polyamide-6), focusing on the kinetics and isotherms of these interactions. The role of metal cations (Al, Cd, Cu, Pb, Zn) in influencing TEB sorption is also investigated. Our findings highlight critical flaws that invalidate the original article, mainly in the interpretation of TEB physicochemical properties, such as pKa and speciation, and the importance of considering metal ion complexation in environmental risk assessment. The sorption models used by the original authors, although widely used, are questioned for their accuracy in representing real-world scenarios.

Enhanced adsorption of tylosin by ordered multistage porous carbon and efficient in-situ regeneration of saturated adsorbents by activated persulfate oxidation: Performance, mechanism and multiple cycles

In this study, a novel ordered multistage porous carbon (OMPC) with a micro-mesoporous structure was prepared and used for the removal of tylosin (TYL). The porous material, carbonized at 900 °C (OMPC-900), exhibited micro-mesoporous structures with pore sizes of 0.71 nm and 3.63 nm, while had a specific surface area of 1300.02 m2 g-1. OMPC-900 demonstrated a maximum adsorption capacity of 341.28 mg g-1 for TYL in water by electrostatic attraction, hydrogen bonding, π-π interactions, and pore-filling mechanisms, which is 6.41 times higher than that of activated carbon. The TYL-saturated adsorbents could be efficiently regenerated by in-situ oxidation through the activation of persulfate (PDS), achieving a regeneration rate of 94.17%, significantly higher than that of activated carbon (55.22%). The excellent regeneration performance may be attributed to the presence of -C=O and graphitic carbon in the adsorbent, which promotes the production of free radicals (•OH, SO4•- and •O2-) and non-free radicals. Among these, the non-radical pathways (1O2 and electron transfer) played a key role in the degradation of TYL loaded on the adsorbent. OMPC-900 maintained stable regenerative adsorption performance of 80.85% after five in-situ regeneration, and the normalized adsorption capacity per unit surface area increased from 0.21 to 0.39 mg m-2, which may be due to that the increase in oxygen-carbon ratio and surface defects improved the adsorption sites activity of the regenerated adsorbent. In comparison to conventional pyrolysis and organic solvent elution, oxidative regeneration through the activation of PDS is a more efficient and sustainable method.

Sorption behaviour of tebuconazole on microplastics: kinetics, isotherms and influencing factors

Microplastics (MPs) and pesticides are two classes of environmental pollutants and have become global challenges. MPs could adsorb substantial environmental pollutants, which may affect their transportation, distribution and cause combination toxicity. Therefore, the study of sorption properties and mechanisms is the basis of the ecological risk assessment of co-exposure of pesticides and MPs. In this research, typical triazole fungicide tebuconazole (TEB) is selected as a model pollutant, and its sorption behaviour was investigated by kinetic and isotherm models. Meanwhile, a series of environmental influencing factors, like pH, salinity, and metals were conducted. Results showed that the sorption of TEB on MPs could reach equilibrium at 24 h, and the sorption capacity followed the order of PA (polyamide) > PS (polystyrene) > PP (polypropylene). The pseudo-second-order model was the most appropriate model to describe kinetic data, and the Freundlich model was well fit for PA sorption isotherms, in contrast the Langmuir model is better for PP and PS. Additionally, the pH of the solution, salinity, and metals have an important effect on sorption. Combined with Fourier Transform Infrared Spectroscopy and environmental influencing factors, the sorption mechanisms were mainly electrostatic interaction and hydrogen bond for PA and PP, and hydrophobic force, intermolecular force, and electrostatic force for PS, respectively.

An ultra-light sustainable sponge for elimination of microplastics and nanoplastics

The currently established tools and materials for elimination of the emerging contaminants from environmental and food matrices, particularly micro- and nano-scale plastics, have been largely limited by complicated preparation/operation, high cost, and poor degradability. Here we show that, crosslinking naturally occurring corn starch and gelatin produces ultralight porous sponge upon freeze-drying that can be readily enzymatically decomposed to glucose; The sponge affords capture of micro- and nano-scale plastics into its pores by simple pressing in an efficiency up to 90% while preserving excellent mechanical strength. Heterogeneous diffusion was found to play a dominant role in the adsorption of microplastics by the starch-gelatin sponge. Investigations into the performance of the sponge in complex matrices including tap water, sea water, soil surfactant, and take-out dish soup, further reveal a considerably high removal efficiency (60%∼70%) for the microplastics in the real samples. It is also suggested tiny plastics in different sizes be removable using the sponge with controlled pore size. With combined merits of sustainability, cost-effectiveness, and simple operation without the need for professional background for this approach, industrial and even household removal of tiny plastic contaminants from environmental and food samples are within reach.

Efficient degradation of tylosin by Klebsiella oxytoca TYL-T1

Tylosin is widely used in livestock; however, the release of tylosin through animal manure can cause serious environmental problems. In this study, a new tylosin-degrading strain, TYL-T1, was isolated. Its phylogenetic similarity to Klebsiella oxytoca was found to be 99.17 %. TYL-T1 maintained good growth at 40 °C over a broad pH range (4.0-10). TYL-T1 degraded 99.34 % of tylosin in 36 h under optimal conditions (tylosin initial concentration: 25 mg/L, pH: 7.0, and temperature: 35 °C). After LC-MS-MS analysis, a new degradation pathway for tylosin was proposed, including ester bond breaking of the macrolide lactone ring, redox reaction, and loss of mycinose and mycarose. Based on a transcriptome analysis, 164 genes essential for degradation were upregulated through hydrolysis and redox of tylosin. Among various transferases, lipopolysaccharide methyltransferase, glycogen glucosyltransferase, and fructotransferase were responsible for tylosin degradation. The present study revealed the degradation mechanism of tylosin and highlighted the potential of Klebsiella oxytoca TYL-T1 to remove tylosin from the environment.

A comparative study on the adsorption behavior and mechanism of pesticides on agricultural film microplastics and straw degradation products

Straw will degrade into segment, powder and crystalline cellulose, while the agricultural film will degrade into microplastics (MPs) in farmland soils. The specific surface area of these micro-particles increases and many new functional groups are formed in the degradation process, which can be a good vector of pesticides. To more accurately and truly analyze the risk of main imported substances and their degradation products against pollutants in soil, the adsorption behavior and mechanism of four commonly used pesticides on aged polyethylene microplastics (APE), wheat straw segment (WSS), wheat straw powder (WSP), and straw crystalline cellulose (SCC) were analyzed and compared through batch adsorption experiments and infrared spectrum. The adsorption kinetics of four pesticides on MPs and straw degradation products tended to be pseudo-second-order kinetics; the adsorption isotherms of pesticides on APE and SCC tended to fit the Freundlich model, while on WSP and WSS tended to fit the Langmuir model. The adsorption was a spontaneous endothermic increase process, suggesting that the main adsorption force of pesticides on MPs and straw degradation products was hydrophobic diffusion. The adsorption of pesticides against WSP and WSS still had a certain π-π conjugation and electrostatic interaction. And the adsorption amount on the straw degradation products followed the order of WSP > WSS > APE > SCC, presumably related to the specific surface area and pore volume of the adsorbent. As WSP, WSS could adsorb more pesticides, the straw returning to the field can be used for slow-release of pesticides to reduce the dosage of pesticides.

Insight into interactions of polystyrene microplastics with different types and compositions of dissolved organic matter

Microplastics (MPs), as newly emerging pollutants, may interact with dissolved organic matter (DOM) widely present in the environment after entering the environment, thereby influencing the migration and transformation of MPs. The interaction characteristics and mechanism between DOM and MPs are restricted by many factors, and the current mechanism remains unclear. Thus, we explored the combination of MP with different types and compositions of DOM (fulvic acid (FA) and humic acid (HA)). Adsorption experiments revealed that MP has high adsorption affinity for all four DOMs, particularly FA. Meanwhile, the affinity of MP-DOM was also examined using excitation-emission matrix (EEM) analyses and fluorescence quenching method (excitation emission matrix-parallel factor analysis (EEM-PARAFAC)). Aromatic substances and hydrophobic substances dominate all DOM samples. For all DOM types tested, the quenching curve varies considerably with the type and compositions of DOM. In addition, three fluorescent components exhibited significant fluorescence quenching over time. The interaction mechanism of MPs and DOM at the molecular level was further elucidated by utilizing two-dimensional (2D) Fourier transformation infrared (FTIR) correlation spectroscopy (COS) analysis, which revealed that the oxygen-containing functional group in MPs was the most preferred DOM binding structure. This work was facilitated to explore the environmental behavior of MPs and formation of secondary MPs under natural conditions.

A Zn/Co bimetal zeolitic imidazolate framework material as a catalyst to activate persulfates to degrade tylosin in aqueous solutions

The bimetallic catalyst ZIF-11(Zn/Co)-2 activates persulfates and has an excellent removal effect on tylosin in aqueous solutions.

Effect of co-digestion of tylosin fermentation dreg and food waste on anaerobic digestion performance

In this study, the effects of adding different food waste proportions (volatile solids ratio of 3:7, 5:5, 7:3) to tylosin fermentation dreg on anaerobic digestion were investigated. The results showed that the co-digestion group (294-399 mL·g-VS^-1) increased methane production by 14.8%-55.5% compared with tylosin fermentation dreg alone-digestion (256 mL·g-VS^-1). The correlation analysis showed that pH, total volatile fatty acids and acetic acid were the most important factors affecting cumulative methane production. Tylosin in the solid and liquid phases decreased significantly after anaerobic digestion, indicating that tylosin could be effectively removed by co-digestion, and the total removal rate was 68.2%-83.7%. Therefore, due to the satisfactory methane yield and the tolerable tylosin removal rate, it is feasible to make the co-digestion of tylosin fermentation dreg and food waste.

Sorption of Sulfamethoxazole on Inorganic Acid Solution-Etched Biochar Derived from Alfalfa

The properties of alfalfa-derived biochars etched with phosphoric (PBC) or hydrochloric acid (ClBC) compared with raw materials (BC) were examine in this paper. SEM, FT-IR, XRD, BET and elemental analysis were performed to characterize the micromorphology and chemical structure comprehensibly. The results showed that the porous structure was enhanced, and surface area was increased via etching with inorganic acids. Batch adsorption experiments were performed for sulfamethoxazole (SMX) to biochars. The experimental data showed that modified biochars exhibited higher adsorption capacity for SMX, i.e., the adsorption quantity of ClBC and PBC had risen by 38% and 46%. The impact on pH values suggested that the physisorption, including pore-filling and electrostatic interaction, might be applied to original biochar. In addition, chemisorption also played a role, including hydrogen bonding, π-π electron donor acceptor interaction (π-π EDA), and so on. Furthermore, both pH and coexisting ions also had a certain effect on sorption. Enhancement of the electrostatic attraction between biochar and SMX might also account for the enhanced capacity of SMX at pH < 7, and coexisting ions could decrease the amount of SMX adsorbed onto biochars, mainly because of competition for adsorption sites.

One-step synthesis of functional metal organic framework composite for the highly efficient adsorption of tylosin from water

Functional metal organic framework composite can effectively remove antibiotics from environmental water samples. However, designing excellent adsorbents with multiple active sites via a rapid one-step method is still a challenging problem. A novel metal organic framework composite (UiO-66-NH₂-AMPS) was synthesized through one-step polymerization by adding functional monomer 2-acrylamide-2-methylpropanesulfonic acid (AMPS) during the preparation of UiO-66-NH₂. The microstructure and morphology of the UiO-66-NH₂-AMPS composite were characterized, and the adsorption performance towards tylosin (TYL) in water was explored by equilibrium adsorption experiment. The results illustrated that the adsorption equilibrium can be reached within 1 h, and the maximum binding amount of UiO-66-NH₂-AMPS for TYL was 161.60 mg g^-1, which was approximately 2.1-329 times of that of the other adsorbents. The pseudo second-order kinetic and Liu isotherm model were suitable for the adsorption process, and thermodynamic study displayed that the adsorption of UiO-66-NH₂-AMPS composite for TYL is spontaneous and endothermal. The infrared and X-ray photoelectron spectra exhibited that hydrogen bond and electrostatic interaction were the primary recognition force for TYL. The UiO-66-NH₂-AMPS composite have been successfully applied to remove TYL from environmental water. After 5 cycles, the removal efficiency of UiO-66-NH₂-AMPS was still above 91.30%.

Ultrasound-engineered synthesis of WS2@CeO2 heterostructure for sonocatalytic degradation of tylosin

The main aim of the present investigation was the intercalation of WS₂ nanosheets in the structure of ceria (CeO₂) to be used for the efficient catalytic destruction of tylosin (TYL) as a macrolide antibiotic in water. As-synthesized heterostructured catalyst was placed in a sono-reactor (40 kHz and 300 W) in order to degrade TYL through the sonocatalysis. 15 wt% WS₂/CeO₂ was chosen for performing the systematic experiments. Decreasing the concentration of TYL, along with increasing the WS₂/CeO₂ dosage led to reduced degradation efficiency. The water hardness was demonstrated to be a suppressive agent on the sonocatalysis of the target pollutant. As-generated holes, OH, and also O₂^- were responsible for the degradation of TYL. Increasing the ultrasound power and operating temperature enhanced the degradation efficiency. The degradation rate boosted up when the temperature was raised from 10 °C (0.0107 1/min) to 40 °C (0.0165 1/min). Moreover, the lowest activation energy (E_a) for sonocatalytic degradation was obtained as 10.81 kJ/mol. The sonocatalytic activity of WS₂/CeO₂ in the sono-reactor encountered insignificant change within five consecutive operational runs (~15% reduction). The mechanism and pathways of the sonocatalytic decomposition of TYL are also proposed.

Cellulase modified waste biomass to remove sulfamethazine from aqueous solutions

The objective of this work is to find a simple and environmentally friendly way to prepare high efficiency adsorbent from maize stover by cellulase. The characteristics of the original maize cob (MC), maize husk (MH), maize straw (MS), and its cellulase modified form (MMC, MMH and MMS) were detected by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Batch adsorption experiments indicated that the adsorption followed the pseudo-second-order kinetic model, and the adsorption capacity of sulfamethazine (SMT) to adsorbents was in order of MMC > MMS > MMH > MC > MS > MH. The adsorption isotherm data of SMT on original materials were consistent with Freundlich models, while Henry models were more suitable for the modified materials. The adsorption was affected by pH and ionic strength which demonstrated the interaction between π-π EDA and H bonds might be an important factor in the adsorption of SMT on maize stover. The results of FTIR and two-dimensional correlation spectroscopy (2D-COS) analysis further demonstrated that oxhydryl and aromatic structures in the modified maize stover could interact with SMT via H bonds and π-π EDA interaction, respectively. This work provides a green way to remove SMT from aqueous solution, and new insights into the mechanisms of adsorption of SMT on stover materials.

Photocatalytic degradation efficiency of hazardous macrolide compounds using an external UV-light irradiation slurry reactor

The current work investigates the removal of two hazardous macrolide molecules, spiramycin and tylosin, by photodegradation under external UV-light irradiation conditions in a slurry photoreactor using titanium dioxide as a catalyst. The kinetics of degradation and effects of main process parameters such as catalyst dosage, initial macrolide concentration, light intensity and stirring rate on the degradation rate of pollutants have been examined in detail in order to obtain the optimum operational conditions. It was found that the process followed a pseudo first-order kinetics according to the Langmuir-Hinshelwood model. The optimum conditions for the degradation of spiramycin and tylosin were low compound concentration, 1 g L^-1 of catalyst dosage, 100 W m^-2 light intensity and 560 rpm stirring rate. Then, a maximum removal (more than 90%) was obtained after 300 min of irradiation time. Furthermore, results show that the selection of optimized operational parameters leads to satisfactory total organic carbon removal rate (up to 51%) and biochemical oxygen demand to chemical oxygen demand ratio (∼1) confirming the good potential of this technique to remove complex macrolides from aqueous solutions.

Improved phenol sequestration from aqueous solution using silver nanoparticle modified Palm Kernel Shell Activated Carbon

Modified Palm Kernel Shell Activated Carbon (PKSAC) using silver nanoparticle (Ag-NPs-PKSAC) was investigated on phenol uptake from aqueous solution. Effects of temperature (500–700 °C), time (90–120 min), and alkaline concentration (0.1–0.5 M) were studied on the yield and methylene blue numbers for the synthesis. Effects of initial concentration (100–200 mg/L), agitation (150–250 rpm), contact time (30–120 min), and adsorbent dosage (0.15–0.25 g) were studied in a batch experiment on percentage removal of phenol. The PKS, char, PKSAC and Ag-NPs-PKSAC were characterized using BET, FTIR, SEM, and proximate analyses. The synthesis of PKSAC was optimum at 608 °C, 0.5 M KOH, and carbonization holding time of 60 min. The optimum phenol uptake was 85.64, 90.29 and 91.70% for PKSAC, Ag-NPs-PKSAC, and commercial adsorbent, respectively. The adsorption mechanism of phenol followed the Langmuir isotherm and best described as physio-sorption with pseudo-second-order kinetics. Phenol exhibits high affinity (ΔS° = 0.0079 kJ/mol K) for Ag-NPs-PKSAC with favorable adsorption (ΔG° = -1.551 kJ/mol) at high temperature due to endothermic (ΔH° = 1.072 kJ/mol) nature of the system. The result obtained in this study compared favorably with the literature.

Adsorptive removal of surfactant using dolochar: A kinetic and statistical modeling approach

Disturbingly high rates of consumption of surfactants in household and industries have led to mark them as emerging contaminants in the environment. In the present work, removal of sodium dodecyl sulfate (SDS), an anionic surfactant, using an industrial waste (dolochar) was explored. The adsorbent material was characterized with the help of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Kinetic evaluation was performed using first, pseudo-first, second, and pseudo-second order models. Adsorption of SDS over dolochar was expressed best by pseudo-second order kinetic model with regression coefficient (R² ) of .99. Three input parameters including adsorbent dose (20-10 g/L), initial concentration (30-100 mg/L) of the surfactant, and contact time (2-60 min) were chosen for optimization using response surface methodology based on Box-Behnken design (BBD) approach. A total of 15 experiments were run to examine the effect of these variables on removal of SDS by dolochar in a multivariate system. A regression analysis indicated the experimental data fitted well to a quadratic polynomial model with coefficient of regression (R² ) as .99. ANOVA and lack-of-fit test depicted the precision and efficiency of the model. The optimized conditions for SDS removal were found to be adsorbent dose 16.62 g/L, contact time 40 min, and initial concentration 47 mg/L with removal efficiency as 98.91%. PRACTITIONER POINTS: Daily ablutions and use of personal care products introduce a number of surfactants and recalcitrant compounds into the environment. Adsorption is a handy and easy to operate treatment technique to remove graywater pollutants. Kinetic and statistical modeling may be recommended as one of the most prominent tools to understand the removal mechanism. Decentralized treatment of graywater using industrial wastes is recommended as sustainable solution in the developing nations.

Effect of microplastic size on the adsorption behavior and mechanism of triclosan on polyvinyl chloride

Microplastics in water environment and its ability to load various environmental pollutants have attracted wide attention in recent years. However, effect of microplastic size on the adsorption behavior of environmental pollutants and interaction mechanism has not been thoroughly explored. In this study, triclosan (TCS) was selected as model pollutant, and polyvinyl chloride (PVC) with different particle sizes (small size (<1 μm) is recorded as PVC-S and PVC-L means large particle size of about 74 μm) were used as the typical microplastics, the adsorption behavior of TCS on PVC was investigated by studying kinetics, isotherms, and other influencing factors, such as pH and salinity. The results indicate PVC-S has greater distribution coefficient k_d values of TCS (1.35 L/g > 1.05 L/g) and stronger adsorption capacity (12.7 mg/g > 8.98 mg/g) compared with PVC-L, which may be due to higher specific surface area, stronger hydrophobicity and relatively small electronegative property of PVC-S. Moreover, the initial pH value and salinity of the solution played crucial role in the adsorption process. The distribution diffusion mechanisms (including liquid-film diffusion and intra-particle diffusion), hydrophobic interaction, electrostatic interaction, halogen bonding, and hydrogen bonding may be the important reasons for adsorption. These findings show that MPs with different particle sizes have vary adsorption behaviors and load capacities for environmental pollutants, which deserve our further concerned.

Removal of p-cresol and tylosin from water using a novel composite of alginate, recycled MnO2 and activated carbon

For sustainable production, there is an urgent need to minimize the adverse environmental impacts of swine farming, which is a major contributor of the pollutants p-cresol and tylosin. Novel reactive composite alginate beads (CAB-MOACs) were fabricated by combining alginate with activated carbon (AC) and MnO₂ recovered from spent battery waste and used for efficient removal of p-cresol and tylosin from water. Batch experiments were carried out under varying pH (3-11), temperature (15-50 °C), and agitation speed (50-200 rpm) to understand their effects on removal efficiency. The CAB-MOACs had better removal efficiency for p-cresol and tylosin than alginate beads alone or beads containing only AC or MnO₂. Adsorption to CAB-MOACs followed pseudo-second-order kinetics (R²≥0.98) and Langmuir isotherm models (R²≥0.95). CAB-MOACs showed higher removal efficiency (∼99.9% after 10 h) compared to beads containing only immobilized MnO₂ (60-70%) or AC (94-96%). Regeneration and reuse performance of the CAB-MOACs was excellent through five cycles, although slightly better for p-cresol than tylosin. With low-cost manufacturing and beneficial utilization of hazardous waste such as spent batteries, the newly developed composite beads show potential as an effective adsorbent for treating wastewater effluent containing emerging contaminants like p-cresol and tylosin. Future studies may focus on product refinement and large-scale testing on actual wastewaters.

Utilizations of agricultural waste as adsorbent for the removal of contaminants: A review

In recent years, various industrial activities have caused serious pollution to the environment. Due to the low operating costs and high flexibility, adsorption is considered as one of the most effective technologies for pollutant management. Agricultural waste has loose and porous structures, and contains functional groups such as the carboxyl group and hydroxyl group, so it can be invoked as biological adsorption material. Agricultural waste gets the advantages of a wide range of sources, low cost, and renewable. It has a good prospect for the comprehensive utilization of resources when used for environmental pollution control. This article summarized the current research status of agricultural waste in adsorbing pollutants, which pointed out the influencing factors of adsorption, expounded the adsorption mechanism of biological adsorption and introduced the related parameters of adsorption, proposed the application of adsorbents in engineering including adsorption in liquid and gas phases, at the same time it gave the future development prospect of agricultural waste as adsorbent.

Sorption properties of tylosin on four different microplastics

After oxidation, abrasion and crushing, microplastics (MPs) can enter the aqueous environment and may adsorb surrounding organic pollutants, altering its migration and spatial distribution. Therefore, an investigation of the sorption properties and mechanism of organic pollutant on MPs can offer a theoretical basis for scientific evaluation of their ecological risks. Using tylosin (TYL) as a model pollutant, the sorption performance of MPs was examined via a series of batch equilibrium experiments which resulted the sorptive removal of TYL on MPs reached equilibrium at 36 h, and the sorption ability of TYL on the MPs followed the order of PE (polyethylene) < PP (polypropylene) < PS (polystyrene) < PVC (polyvinyl chloride). The pseudo-second-order model well fit for the sorption kinetics data, and the adsorption isotherms could be better described by Freundlich equation rather than Langmuir model. Additionally, the initial solution pH and ionic strength played important roles across the adsorption. The sorption procedure of TYL on MPs was dominated by electrostatic interaction, surface complexation and hydrophobic interaction.

Iron and manganese oxides modified maize straw to remove tylosin from aqueous solutions

Maize straw modified by iron and manganese oxides was synthesized via a simple and environmentally friendly method. Three maize straw materials, the original maize straw, maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides, were detected by SEM, BET, XPS, XRD and FTIR. The results showed that maize straw was successfully modified and maize straw modified by iron and manganese oxides has a larger surface area than MS. According to the experimental data, the sorption trend could conform to the pseudo-second-order kinetic model well, and the sorption ability of tylosin on sorbents followed the order of original maize straw < maize straw modified by manganese oxides < maize straw modified by iron and manganese oxides. The study indicated that manganese oxides and iron-manganese oxides could significantly enhance the sorption capacity of original maize straw. The sorption isotherm data of tylosin on original maize straw fit a linear model well, while Freundlich models were more suitable for maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides. The pH, ionic strength and temperature can affect the sorption process. The sorption mechanisms of tylosin on iron and manganese oxides modified maize straw were attribute to the surface complexes, electrostatic interactions, H bonding and hydrophobic interactions.

Influence of sodium dodecyl sulfate coating on adsorption of methylene blue by biochar from aqueous solution

Biochar is regarded as a promising new class of materials due to its multifunctional character and the possibility of effectively coupling different properties. With increasing introduction into the environment, environmental chemicals such as surfactants will load onto the released biochar and change its physicochemical characteristics and adsorption behavior toward pollutants. In this study, sodium dodecyl sulfate (SDS), as one type of anionic surfactant, was coated onto biochar with different loading amounts. The influence of SDS loading onto biochar's physicochemical properties were investigated by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, zeta potential and Brunauer-Emmett-Teller (BET) surface area and pore size distribution analysis. Results showed that the pore size of the biochar decreased gradually with the increase of SDS loading because of the surface-adsorption and pore-blocking processes; the pH of the point of zero charge (pH_PZC) decreased with increasing SDS loading. Although surface-coating with SDS decreased the pore size of the biochar, its adsorption capacity toward Methylene Blue (MB) significantly increased. The biochar-bound SDS introduced functional groups and negative charges to the biochar surface, which could thus enhance the adsorption of MB via hydrogen bonding and electrostatic interaction. The results can shed light on the underlying mechanism of the influence of anionic surfactants on the adsorption of MB by biochar.

Maize straw decorated with sulfide for tylosin removal from the water

MS-ZnS and MS-ZnS:Mn complexes were synthesized via a simple method. The results showed that sulfide was successfully loaded on the maize straw. The results of fitting the experimental data showed that the sorption conforms to the pseudo-second-order kinetics, and the TYL sorption on MS fit the Henry model well, but the Freundlich model was more suited to MS-ZnS and MS-ZnS:Mn. In addition, the k_f values of MS-ZnS (206.0(mg/kg)/(mg/L)ⁿ) and MS-ZnS:Mn (382.5(mg/kg)/(mg/L)ⁿ) were significantly greater than that of MS (72.2(mg/kg)/(mg/L)ⁿ), indicating that ZnS and ZnS:Mn could improve the sorption capacity of TYL on MS. The pH, ionic strength and temperature influence the sorption process, and the sorption ability of TYL on MS-ZnS and MS-ZnS:Mn showed little change when the solution pH was > 5; the amount of TYL sorption on the adsorbents gradually decreased with the increasing concentration of KNO₃. Electrostatic interactions, H bonding and hydrophobic interactions are involved in the sorption of TYL on MS, MS-ZnS and MS-ZnS:Mn, and compared with MS, the main mechanism is surface complexation. This research can provide technical support for the utilization of biomass and the restoration of water polluted by antibiotics.