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This paper aims to focus on studying the batch desorption of adsorbed crystal violet (CV) from date stones (Phoenix dactylifera), untreated (UDS) and treated using NaOH (TDS).

The process variables such as different desorbing agents, volume and concentration of the desorbing agent, contact time, dye concentration before adsorption and temperature affecting CV desorption from CV-loaded untreated date stones (CV@UDS) and treated adsorbent (CV@TDS) were optimized. The UDS and TDS were regenerated using 0.6 m HCl as eluent.

The HCl solution was an excellent eluent for the CV desorption from CV@UDS (96.45%) and CV@TDS (98.11%). The second-order model and the Langmuir model well exemplified experimental data with maximum desorption capacities were 63.29 mg g⁻¹ for the CV@UDS and 243.90 mg g⁻¹ for the CV@TDS. The calculated thermodynamic showed that the CV desorption was spontaneous, endothermic and physical. Good regeneration and reusability of UDS and TDS for the CV removal for four consecutive adsorption–desorption cycles.

This study provided a good example of reusing UDS and TDS with NaOH for fast removal of a toxic organic pollutant, CV from the wastewaters.

The use of UDS and TDS with NaOH for the first time for desorption study and their reusability to removing CV from their aqueous solutions.

This study aims to prepare an imprinted composite membrane with grafted temperature-sensitive blocks for the efficient adsorption and separation of rhenium(Re) from aqueous solutions.

PVDF resin membrane was used as the substrate, dopamine and chitosan (CS) were used to modify the membrane surface and temperature-sensitive block PDEA was grafted on the membrane surface. Then acrylic acid (AA) and N-methylol acrylamide (N-MAM) were used as the functional monomers, ethyleneglycol dimethacrylate (EGDMA) as the cross-linker and ascorbic acid-hydrogen peroxide (Vc-H₂O₂) as the initiator to obtain the temperature-sensitive ReO4⁻ imprinted composite membranes.

The effect of the preparation process on the performance of CS–Re–TIICM was investigated in detail, and the optimal preparation conditions were as follows: the molar ratios of AA–NH₄ReO₄, N-MAM and EGDMA were 0.13, 0.60 and 1.00, respectively. The optimal temperature and time of the reaction were 40 °C and 24 h. The maximum adsorption capacity of CS–Re–TIICM prepared under optimal conditions was 0.1071 mmol/g, and the separation was 3.90 when MnO4⁻ was used as the interfering ion. The quasi first-order kinetics model and Langmuir model were more suitable to describe the adsorption process.

With the increasing demand for Re, the recovery of Re from Re-containing secondary resources becomes important. This study demonstrated a new material that could be separated and recovered Re in a complex environment, which could effectively alleviate the conflict between the supply and demand of Re.

This contribution provided a new material for the selective separation and purification of ReO4⁻, and the adsorption capacity and separation of CS–Re–TIICM were increased with 1.673 times and 1.219 time compared with other Re adsorbents, respectively. In addition, when it was used for the purification of NH₄ReO₄ crude, the purity was increased from 91.950% to 99.999%.

The purpose of the paper is to separate and purify flavonoids existed in Lamiophlomis rotata (Benth.) Kudo. by macroporous adsorption resin (MAR) mixed-bed technology.

The adsorption and desorption parameters were characterized by UV-VIS spectrophotometry. The optimal MAR mixed bed was screened based on the adsorption experiments; the experiment process was investigated by the order of single, two and three MAR mixed bed separately; and the adsorption performance, which was composed by the authority of 80 per cent adsorption ratios and 20 per cent desorption ratios, was adopted to screen MAR mixed bed for flavonoids. The adsorption dynamic investigated the order of reaction first, and then the adsorption mechanism was researched further. The adsorption thermodynamic investigated the adsorption isotherm first, and then the adsorption feature was analyzed.

This research found that MAR mixed bed of LS-840 + LSD301 with mass ratio of m_LS840:m_LSD301 = 3:2 was the optimized combination, and the optimal conditions of the adsorption were volume V = 50 mL, time t = 6.5 h, T = 40°C. The desorption conditions were ethanol content = 70 per cent, desorption time t = 3.0 h, T = 40°C. The adsorption dynamic experimental data fitted better to the pseudo-second-order, and the intra-particle-diffusion model was more suitable for expression of the adsorption mechanism in mesopores process, whereas the homogeneous particle-diffusion model was more suitable in microspores. The adsorption was a physical and multilayer adsorption, and the adsorption driving force was disappeared as it transferred to the fourth layer.

Find an efficient way to separate flavonoids that useful for human’s health, which can not only utilize of plant resources effectively, but also make outstanding contributions to medical industry. It has very high economic and social value.

This contribution provided a new way to separate flavonoids from Lamiophlomis rotata (Benth.) Kudo. Under the optimal conditions, the adsorption rate (F) of MAR mixed bed LS-840 + LSD301 to the flavonoids was 97.81 per cent, the desorption rate (D) was 90.02 per cent and the purity of flavonoids was dramatically increased about 2.08 fold of the crude extract from 28 to 58.4 per cent, and the recovery yield of flavonoids arrived at 91.6 per cent after a circle of adsorption/desorption operation.

A novel grafted temperature-responsive ReO₄⁻ Imprinted composite membranes (Re-ICMs) was successfully prepared by using polyvinylidene fluoride (PVDF) resin membranes as substrates, this study aimed to separate and purify ReO effectively.

Re-ICMs were synthesized by PVDF resin membranes as the substrate, acrylic acid (AA), acrylamide (AM), ethylene glycol dimethacrylate (EGDMA) were functional monomers. The morphology and structure of Re-ICMs were characterized by scanning electron microscope and Fourier transform infrared spectroscopy.

The maximum adsorption capacity toward ReO₄⁻ was 0.1,163 mmol/g and the separation decree had relation to MnO₄⁻ was 19.3. The optimal operation conditions were studied detailedly and the results as follows: the molar ratios of AA, AM, EGDMA, ascorbic acid, NH4ReO₄, were 0.8, 0.96, 0.02, 0.003 and 0.006. The optimal time and temperature were 20 h and 40°C, respectively. The Langmuir and pseudo-second-order models were fit these adsorption characteristics well.

Rhenium (Re) is mainly used to chemical petroleum and make superalloys for jet engine parts. This study was representing a technology in separate and purify of Re, which provided a method for the development of the petroleum and aviation industry.

This contribution provided a novel method to separate ReO₄⁻ from MnO₄⁻. The maximum adsorption capacity was 0.1163 mmol/g at 35°C and the adsorption equilibrium time was within 2 h. Meanwhile, the adsorption selectivity rate ReO₄⁻/MnO₄⁻ was 19.3 and the desorption rate was 78.3%. Controlling the adsorption experiment at 35°C and desorption experiment at 25°C in aqueous solution, it could remain 61.3% of the initial adsorption capacity with the adsorption selectivity rate of 13.3 by 10 adsorption/desorption cycles, a slight decrease, varied from 78.3% to 65.3%, in desorption rate was observed.

The purpose of this paper is to separate and purify flavonoids existing in the leaves of Sophora japonica by a novel method, macroporous adsorption resin (MAR) mixed-bed technology, and the optimal MAR mixed bed was screened based on the adsorption experimental result with the order of single, two, three and four MAR mixed bed separately.

The adsorption performance of MAR and MAR mixed bed for flavonoids was studied using ultraviolet – visible (UV-VIS) spectrophotometry.

This research showed that the MAR mixed bed of LZ-54 + LZ-67 with a mass ratio of mLZ-54:mLZ-67 = 1:1 was the optimized combination with the optimal conditions of adsorption (volume V = 140 mL, pH = 5, T = 35°C) and desorption (liquid ratio R = 50 per cent, T = 30°C, pH = 6) obtained, relatively.

This study aims to find an efficient way of separating flavonoids and other components that are useful for human health from Sophora japonica, which is complying with the policy of sustainable development.

This contribution provided a novel way to separate flavonoids from Sophora japonica. Under the optimal conditions, the adsorption rate (F) of MAR mixed bed LZ-54 + LZ-67 to the flavonoids was 63.65 per cent, the desorption rate (D) was 87.31 per cent and the purity was dramatically achieved at 58.17 per cent from 17.67 per cent after a round of adsorption/desorption operation.

This paper aims to evaluate the separation and purification characteristics of flavonoids from polygonum cuspidatum (PC) extracts by using macroporous adsorption resins (MAR) mixed bed to improve the utilization rate of flavonoids.

Taking the separation performance of flavonoids as an evaluation index, the best MAR were screened from 31 sorts of MAR and combined the best MAR to form a MAR mixed bed for adsorption and separation of flavonoids.

By studying the separation conditions that affect flavonoids, the results showed that resin LZ-72 has best separation and purification effect on flavonoids under the optimal adsorption and desorption conditions, the purity of the obtained flavonoid compound reaches 82.50%, 2.66 times of the initial extract, and the recovery rate reaches 89.70%. Theoretical research results have shown that the adsorption of flavonoids by MAR conforms to the pseudo-second-order kinetics and Freundlich models.

Because the flavonoids in PC have great medicinal value, the purpose of this work is to develop a method of separating and purifying flavonoids from PC, which will provide a certain foundation for the development of medicine.

This contribution provided a novel way to separate flavonoids from PC. Under the optimal conditions, the content of flavonoids in the product was increased 2.66-fold from 31.01% to 82.50%, and the recovery yield was 89.70%.

The purpose of this study is to prepare composite of chitosan-modified smectite clays consisting of montmorillonite and saponite clay minerals and their urea adsorption–desorption study. Prepared materials were designed for slow-release fertilizer application.

Preparation of the composites was conducted by a simple intercalation of chitosan solution and clay suspension followed by hydrogel beads formation. Physicochemical characterization of materials was performed by X-ray diffraction, gas sorption analysis by using Brunauer–Emmett–Teller surface areas and pore volume, water absorbency and Fourier transform-infrared. Urea adsorption and desorption studies of prepared materials were conducted by using batch method, and the adsorbed and desorbed urea content was analyzed by using high-performance liquid chromatography method.

The results revealed that the composites have higher absorptivity and lower absorptivity toward urea from and into water solution compared to raw clay minerals. Adsorption capacity and slow desorption rate of urea from the composites suggested the potential application of the composites as slow urea-releasing agent.

There are many papers that study the formation of chitosan-clay composites, but the study on the urea adsorption–desorption properties based on chitosan-smectite minerals have not been reported. Intensive study related to physicochemical properties and its related kinetics study is an important basic finding for further applications.

The purpose of this paper is to separate and purify flavonoids from glycyrrhiza by macroporous adsorption resin (MAR) mixed-bed technology.

The adsorption performance of MAR and MAR mixed bed for flavonoids was studied using ultraviolet-visible spectrophotometry.

The research shows that the MAR mixed bed of LZ-50+LZ-59 with a mass ratio of LZ-50:LZ-59(m:m) = 1:1 was the optimized combination with the optimal conditions of adsorption (pH = 6, T = 45°C) and desorption (liquid ratio R = 70%, T = 50°C, pH = 8) obtained, relatively.

This paper provides a novel way to separate flavonoids from glycyrrhiza. Under the optimal conditions, the adsorption rate (F) of MAR mixed-bed LZ-50+LZ-59 to the flavonoids was 62.5 per cent/g, the desorption rate (D) was 89.23 per cent and the purity was achieved at 80 per cent.

Graphene is a two-dimensional material. Its use has many advantages in gas sensing, but its long desorption process is problematic. The aim of this paper is to design a graphene-based gas sensor, study the response to NO₂ gas concentrations and find ways to accelerate the desorption process.

In one group, the sensor was placed in air to measure its initial resistance. Then, it was exposed to the NO₂ gas at a certain concentration. Finally, the sensor was exposed to light immediately after NO₂ gas exposure was ended. In another group, the sensor was heated using a heating plate at a stable temperature, before taking the measurements. Then the adsorption and desorption experiments were carried on.

Illumination and heating at a suitable temperature can expedite desorption of NO₂ molecules on graphene.

In the paper, two main methods are introduced to accelerate the desorption process when the NO₂ gas is absorbed on graphene. Through a series of experiments and analysis, the authors found that the recovery time could be reduced observably and the recovery performance of the graphene-based NO₂ sensor could be improved effectively.

This paper aims to explore the adsorption kinetics of syringin from Syringa oblata Lindl. leaves on macroporous resin and develop an efficient, simple and recyclable technology for the separation and purification of syringin.

Static adsorption and desorption properties of six resins were tested to select a suitable resin for the purification of syringin. Langmuir and Freundlich isotherm models were used to estimate the adsorption behavior of syringin on AB-8 resin. Breakthrough point and eluent volume were determined by dynamic adsorption and desorption tests. High-performance liquid chromatography-electrospray ionization-mass spectrometry was applied to identify the syringin in the purified product [syringin product (SP)]. Antioxidant and antibacterial activities of SP in vitro were evaluated by free radical scavenging ability and biofilm formation inhibitory tests.

AB-8 exhibited the most suitable adsorption and desorption capacity. Adsorption isotherm parameters indicated favorable adsorption between AB-8 and syringin. The optimal results were as follows: for adsorption, the sample concentration was 1.85 mg/mL, the sample volume was 3.5 bed volume (BV), the flow rate was 0.5 mL/min; for desorption, the ethanol concentration was 70%, the elution volume was 2.5 BV, the elution velocity was 1.0 mL/min. SP with 80.28% syringin displayed the potent antioxidant activities and inhibitory effects on biofilm formation of Streptococcus suis.

To the best of authors’ knowledge, there are no reports on purifying syringin from Syringa oblata Lindl. leaves using macroporous resins. This paper may also provide a theoretical reference for the purification of other phenylpropanoid glucosides.