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In this study, an iron(III)-loaded magnetic chitosan/graphene oxide composite (Fe-MCG) was synthesized and applied for the adsorptive removal of sulfosalicylic acid (SSA) in aqueous solution. The results obtained from the application of various characterization techniques such as scanning electron microscopy (SEM), vibrating-sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS) prove the successful formation of the composite with enhanced microstructure and superparamagnetic properties. The adsorption capacity of Fe-MCG towards SSA via batch mode reaches up to 135 mg/g at 293 K. The adsorption of SSA onto Fe-MCG is driven by monolayer adsorption with the chemical and physical adsorption processes both playing active roles. The Langmuir isotherm and pseudo-second-order kinetic models were observed to best describe the equilibrium adsorption and kinetic processes, respectively. The values obtained for the associated thermodynamic parameters confirm that the adsorptive process is spontaneous, exothermic and entropy-increasing. The efficacy and reusability of the spent Fe-MCG was studied using 0.01 mol/L NaOH solution. The kinetic process for the desorption of SSA from Fe-MCG is well described by the pseudo-second-order kinetic model. Based on the experimental results and XPS analysis, the underlying mechanisms for the uptake of SSA onto Fe-MCG involve electrostatic forces, complexation, π-π stacking, and hydrogen bonding. Overall, the excellent features of Fe-MCG enhance its potential as an adsorbent for the sequestration of SSA in environmental media.

In this work, a novel adsorbent, activated carbon (PSAC) developed by the activation of pine sawdust's pyrolytic carbon (PSPC), is applied to adsorb 2,4-dichlorophenol (2,4-DCP) and 4-chlorophenol (4-CP). The optimized preparation conditions of PSAC were presented. The results revealed that equilibrium adsorption capacity (q

A novel adsorbent (PN-Fe3O4-IDA-Zr) was developed from the chemical modification of peanut husk (a low cost material) with Fe3O4, iminodiacetic acid (IDA) and zirconium (Zr) and its efficacy for the sequestration of wastewater assessed using Alizarin red (AR) and Acid chrome blue K (AK) as model pollutants. To elucidate the characteristics of the formed adsorbent, analytical techniques such as the Bruauner-Emmet-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffractive spectroscopy (XRD) and vibrating sample magnetometer (VSM) were applied. Results from these studies confirmed the formation of a crystalline mesoporous adsorbent with surface properties which enhanced its usefulness. From the adsorption studies, it was observed that factors such as pH, salts, temperature and contact time influenced the uptake of the anionic dyes. The maximum monolayer capacity of PN-Fe3O4-IDA-Zr for AR was 49.4 mg g−1 (at 313 K) and was well fitted by the Langmuir model with the chemisorption process being the dominant reaction mechanism. In binary systems, PN-Fe3O4-IDA-Zr exhibited higher affinity for AR as compared with AK. The significant removal efficiency exhibited by this novel adsorbent as well as other unique features such as easy retrieval and high regeneration promotes its prospects as an adsorbent for practical wastewater remediation processes.

In this research, the eco-friendly cationic surfactant modified walnut shell (WNS-CTAB) was synthesised to enhance the uptake for bisphenol A (BPA) and Congo red (CR) from aqueous solution. The characterisation of WNS-CTAB was performed using Fourier-transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), etc. to know its physiochemical properties. The adsorption equilibrium results were best described by the Langmuir isotherm model, which confirmed the monolayer adsorption of the pollutant molecules onto the adsorbent’s surface. The maximum monolayer adsorption quantity of WNS-CTAB was established to be 38.5 mg g–1 for BPA and 104.4 mg g–1 for CR at 303 K, respectively. Pseudo-second-order kinetic models described the adsorption kinetics of both BPA and CR. Furthermore, the intra-particle diffusion was applied to analyse the kinetic results and was established that the rate was not solely controlled by diffusion. The mechanisms associated with BPA and CR adsorption onto the WNS-CTAB may include van der Waals interaction, hydrophobic interaction, and electrostatic force. WNS-CTAB demonstrated a good reusability potential with desorption through three successive adsorption-desorption cycles performed in both experiments. Moreover, in the binary system, the adsorption capacity of BPA witnessed a 66% decrease while CR saw marginal reduction of 8.0 %. This suggests that WNS-CTAB had a higher affinity for binding to CR with higher selectivity as compared with BPA. Therefore, WNS-CTAB has exhibited huge potential to serve as a functional material for practical use in the treatment of wastewater.

Coating superparamagnetic iron oxide particles, i.e., Fe3O4, as adsorbents have major advantages over bare adsorbents for water treatment. As a versatile material, zirconium has been extensively studied for phosphate removal. In this study, the Fe3O4 core was pre-coated with branched polyethyleneimine (PEI) first, and then loaded with zirconium to result in a highly selective adsorbent (i.e., Zr-PEI@Fe3O4) for phosphate with a greatly broadened pH range. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), BET surface area, and magnetization were used to characterize the resulting adsorbent and to explore the underlying adsorption mechanism. The adsorption performance of Zr-PEI@Fe3O4 toward phosphate was performed by batch experiment. The results showed that Freundlich model better fit the adsorption isotherms, while the Elovich equation better described the kinetic process. The maximum adsorption capacity of dephosphorization 32.2 mg·g−1 (according to P element) emerged in the condition of 1.0 g·L−1 and pH at 2 with 303 K. The process was spontaneous and endothermic. Zr-PEI@Fe3O4 has the potential to remove phosphate from solution due to its easy separation and some good adsorption property.

Recent progress has been made in the application of novel zirconium-loaded amine-grafted walnut shells as multifunctional adsorbents for the remediation of Alizarin red (AR) and bacteria in aqueous solutions. The morphology and functional groups of ACWNS@Zr were studied using Brunauer-Emmett-Teller (BET) techniques, X-ray diffraction (XRD), pH point of zero charges (pHpzc), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. Adsorption and regeneration tests were carried out in batch and column mode. The ACWNS@Zr had a Langmuir maximum capacity of 415.5 ± 6.1 mg g

Background As two important tumor markers, vascular endothelial growth factor (VEGF) and carcinoembryonic antigen (CEA) have a great value for clinical application in the early diagnosis of cancer. Due to the complex composition of biological samples, the results from combined detection of CEA and VEGF are often taken as a comprehensive indicator in order to make an accurate judgment on a disease. However, most of the current methods can only be used to detect the content of one biomarker. Therefore, it is necessary to explore a simple, rapid, low-cost, and highly sensitive method for the simultaneous detection of CEA and VEGF. Methods Based on specific aptamers and magnetic separation, a time-resolved chemiluminescence enzyme-linked aptamer assay was developed for the simultaneous detections of CEA and VEGF in serum samples. Results Under the optimal conditions, the linear range of the calibration curve for VEGF was from 0.5 to 80 ng mL−1, and the limit of detection was 0.1 ng mL−1. The linear range of the calibration curve for CEA was 0.5 to 160 ng mL−1, and the limit of detection was 0.1 ng mL−1. The established method was applied to detect VEGF and CEA in serum samples. The results were consistent with those of commercial kits. Conclusion The method has high sensitivity and can quickly obtain accurate results, which could greatly improve the measurement efficiency, reduce the cost, and also reduce the volume of sample consumed. It can be seen that the method established in this study has important application value and broad application prospect in clinical diagnosis.

To enhance adsorption capacity of wheat straw (WS) toward copper ion from solution, carbon disulfide was used to modify WS by a facile grafting method through epichlorohydrin and ethylenediamine. So WS containing xanthate groups (XWS) was obtained. The XWS was characterized using elemental analysis, X-ray diffraction, infrared spectroscopy and adsorption property of XWS toward copper ions. The results showed that S was introduced into the surface of WS. The solution pH was in favor of Cu2+ adsorption at pH 5, while NaCl existing in solution was slightly favorable for adsorption. The adsorption kinetic followed the pseudo-second-order kinetic model, while the adsorption isotherm curve was well fitted using the Langmuir model. The adsorption capacity was 57.5 mg·g−1 from experiment. The process was entropy-produced, endothermic and spontaneous in nature. The column adsorption was performed and Yan model was good to predict the breakthrough curve. XWS as adsorbent is promising to remove copper ions from solution, and this offers one way of effective utilization of waste byproduct from agriculture.

In this paper, the potential has been investigated of using the silver(I) 3,5-diphenyltriazolate MOF—AgTz-1 as an adsorbent towards the adsorption of p-nitrophenol (PNP) from water. Based on experimental results, the best adsorption performance can be achieved at room temperature (or slightly elevated temperature) in neutral solution with the adsorption capacity Qmax being 184.8 mg/g (308 K) and 143.5 mg/g (298 K). The adsorption of PNP onto AgTz-1 is pH-dependent: at pH > 8 it can be described by the “one in, one out” anion exchange mechanism; while at pH 7 or less, some neutral 4-nitrophenol molecules may enter the interior of MOF along with 4-nitrophenolate anions via hydrogen-bonding and/or π-π stacking, accompanied by the expansion of MOF structure at higher equilibrium concentrations of PNP at 298 K and 308 K. Moreover, the adsorption efficiency of AgTz-1 remained almost the same after five consecutive cycles of adsorption–desorption.

A highly effective adsorbent of lanthanum-modified D751 resin (D751 resin for macroporous styrene chelated resin, sodium form) was prepared to enhance the effect of removing phosphate from solution. FTIR, SEM were used to explore the functional groups and structural features on the surface of D751-La; XPS analyzed the action mechanism between phosphate and D751-La. The adsorption performance about D751-La toward phosphate was investigated by batch experiment. The results showed that Langmuir, Freundlich, Temkin, Koble-Corrigan as well as Redlich-Peterson models fitted well for the adsorption isotherms. The adsorption kinetics could be better fitted by Double Constant, Elovich, and Pseudo-second-order model. The effect of salinity was not significant, such as Cl− and SO42−. When the solid-liquid ratio was 15 g·L−1 with setting the reaction time as 8 h, the unit adsorption quantity of D751-La to phosphate (calculated in P) reached up to 26.3mg·g−1 under the solution pH=3 at 293 K. The process was spontaneous and exothermic from thermodynamic analysis. It shows that D751-La has potential to remove phosphate from solution.

Modified walnut shell (MWS) was obtained using diethylenetriamine through a grafting reaction and its adsorption capacity toward Cr(VI) was enhanced. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and elemental analysis and the results showed that the modification was effective. To optimize experimental conditions, the effect of temperature, solution pH, salinity, contact time, and Cr(VI) concentration on adsorption quantity were performed in batch mode. It showed that the adsorption ability for Cr(VI) onto MWH can reach 50.1 mg·g−1 at 303 K with solution pH 3. Both the solution pH and salinity had a great impact on the adsorption capacity. The Langmuir model can predict the equilibrium process while the pseudo-second-order model can describe the kinetic process. The Yan model can be used to predict the column process. Additionally, there was also some regeneration ability for Cr-loaded MWH. Consequently, MWS is effective for removing Cr(VI) from solution.

We engineered a tiger nut residue (TNR, a low-cost agricultural waste material) through a facile and simple process to take advantage of the introduced functional groups (cetylpyridinium chloride, CPC) in the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) in batch mode and further investigated its impingement on bacterial growth in a yeast-dextrose broth. The surface characterizations of the adsorbent were achieved through Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller method (BET), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The batch adsorption studies revealed that solution pH, adsorbent dose, temperature, and salt affected the adsorptive capacity of TNR-CPC. The equilibrium data were best fitted by Langmuir isotherm model with a maximum monolayer adsorption capacity of 90.2 mg g