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Abstract An extended (3+1)-dimensional Kadomtsev–Petviashvili–Boussinesq equation is studied in this paper to construct periodic solution, n-soliton solution and folded localized excitation. Firstly, with the help of the Hirota’s bilinear method and ansatz, some periodic solutions have been derived. Secondly, taking Burgers equation as an auxiliary function, we have obtained n-soliton solution and n-shock wave. Lastly, we present a new variable separation method for (3+1)-dimensional and higher dimensional models, and use it to derive localized excitation solutions. To be specific, we have constructed various novel structures and discussed the interaction dynamics of folded solitary waves. Compared with the other methods, the variable separation solutions obtained in this paper not only directly give the analytical form of the solution u instead of its potential $$u_y$$ u y , but also provide us a straightforward approach to construct localized excitation for higher order dimensional nonlinear partial differential equation.

Clustering protocols for underwater acoustic sensor networks (UASNs) have gained widespread attention due to their importance in reducing network complexity. Congestion occurs when the intra-cluster load is greater than the upper limit of the intra-cluster information transmission capacity, which leads to a dramatic deterioration of network performance despite the reduction of network complexity. To avoid congestion, we propose a node load and location-based clustering protocol for UASNs (LLCP). First, a node load and location-based optimization mechanism is proposed. The number of cluster members is optimized based on node load and location to maximize the number of cluster members while avoiding congestion. Then, a node degree and location-based cluster member selection mechanism is proposed to select the optimal cluster members. Finally, a priority-based clustering mechanism is proposed. The node clustering order is adjusted based on the clustering priority to maximize the reduction of network complexity by increasing the average number of cluster members. Simulation results show that our proposed LLCP minimizes the network complexity while avoiding congestion.

Graphitic carbon nitride has long been considered a poor oxygen evolution catalyst. Here, the authors report a simple fluorination strategy to prevent the accumulation of inert C=O on carbon nitride to break through this bottleneck.

Paper-based test strips with on-site visual detection have become a hot spot in the field of target detection. Yet, low specific surface area and uneven deposition limit the further application of test strips. Herein, a novel “turn-on” ratio of molecularly imprinted membranes (Eu@CDs-MIMs) was successfully prepared based on a Eu complex-doped polyvinylidene fluoride membrane for the selective, rapid and on-site visual detection of norfloxacin (NOR). The formation of surface-imprinted polymer-containing carbon dots (CDs) improves the roughness and hydrophilicity of Eu@CDs-MIMs. Fluorescence lifetimes and UV absorption spectra verified that the fluorescence enhancement of CDs is based on the synergistic effect of charge transfer and hydrogen bonding between CDs and NOR. The fluorescent test strip showed a linear fluorescent response within the concentration range of 5–50 nM with a limit of detection of 1.35 nM and a short response time of 1 min. In comparison with filter paper-based test strips, Eu@CDs-MIMs exhibit a brighter and more uniform fluorescent color change from red to blue that is visible to the naked eye. Additionally, the applied ratio fluorescent test strip was combined with a smartphone to translate RGB values into concentrations for the visual and quantitative detection of NOR and verified the detection results using high-performance liquid chromatography. The portable fluorescent test strip provides a reliable approach for the rapid, visual, and on-site detection of NOR and quinolones.

Abstract This paper uses a novel numerical approach to approximate the coupled Cahn–Hilliard equations, which are a highly nonlinear system depicting the phase separation of the homopolymer and copolymer mixtures. The new method is named 3S-IEQ, and its construction and calculation are more straightforward than the invariant energy quadratization and scalar auxiliary variable methods. Notably, we only need to solve two linear decoupled constant-coefficient equations at each time step. Numerical simulations are shown

The present paper considers the blowup properties in trapped dipolar quantum gases modelled by the Gross-Pitaevskii equation. More precisely, through analyzing the temporal evolution of J′(t) in the form of uncertain principle [1], we provide some invariant evolution flows. Based on that, we establish the global existence versus blowup dichotomy of solutions above the mass-energy threshold. Meanwhile, we can estimate the behaviour of solutions with arbitrary large energy.

In this work, a new extended integrable (2+1)-dimensional Kadomtsev–Petviashvili equation is proposed and investigated, which models slowly varying perturbation wave in dispersion fluids. First, the WTC-Kruskal algorithm is applied to exploring the corresponding compatibility condition for this equation in Painlevé sense. Then, N-soliton, periodic, breather solution as well as the mixed form composing of breather and soliton(s) have been derived via Hirota bilinear method and symbolic computation. Moreover, we have derived the rational and semi-rational solutions in terms of “long wave” limit. The rational solutions can be classified as first order line rogue waves and lumps, while the semi-rational solutions have the forms: a hybrid of first order line rogue wave and one soliton, a hybrid of second order line rogue wave and one soliton, a hybrid of lump and soliton(s), a hybrid of lump and breather, a hybrid of lump and periodic solution.

The combining of the heterostructure construction and active sites modification to remodel the traditional wide-band-gap semiconductor SrTiO3 for improving visible light absorption capacity and enhancing photocatalytic performance is greatly desired. Herein, we research a novel GO/Rh-SrTiO3 nanocomposite via a facile hydrothermal method. The champion GO/Rh-SrTiO3 nanocomposite exhibits the superior photocatalytic overall water splitting performance with an H2 evolution rate of 55.83 μmol∙g−1∙h−1 and O2 production rate of 23.26 μmol∙g−1∙h−1, realizing a breakthrough from zero with respect to the single-phased STO under visible light (λ ≥ 420 nm). More importantly, a series of characterizations results showed that significantly improving photocatalytic performance originated mainly from the construction of heterostructure and more active sites rooted in Rh metal. In addition, the possible photocatalytic reaction mechanisms and the transport behavior of photogenerated carriers have been revealed in deeper detail. This work provides an effective strategy for heterostructure construction to improve solar utilization through vastly expanding visible light response ranges from traditional UV photocatalysts.

Microgrid plays an important role in absorbing rural distributed renewable energy and ensuring the reliability of power supply. In order to reduce the waste of clean energy and improve the operation efficiency of microgrid, a cooperative game-based optimization method for microgrid and distribution network is proposed. Firstly, combined with the complementarity of wind power, solar power and biogas power generation in time, the cooperative operation mechanism of micro power is established. Load characteristics are taken as constraints and the minimum operating cost as objective function. Then, a microgrid alliance protocol based on cooperative game theory is proposed, in order to maximize the benefits of microgrids. In the alliance, power surplus microgrid sells electric to power shortage microgrid to realize complementary power supply. So as to improve the distribution efficiency and reduce the overall operation cost. Finally, it proposes a complementary power supply scheme between microgrid alliance and distribution network as well as a revenue distribution method. For the distribution of benefits, Shapley value method is discussed in order to distribute benefits fairly. On the basis of theoretical research, the objective function and constraint conditions are designed to build the algorithm model and write program for simulation. The analysis results show that cooperative game optimization operation of microgrid and distribution network can effectively improve the distribution efficiency and increase benefits.

The current paper devotes to the continuation of the solutions for the Dullin–Gottwald–Holm equation with forcing. Due to forcing, this equation loses the conservation of energy and cannot be regarded as the Hamiltonian system. Thus, through employing the characteristic method and exploiting the balance law, we prove the existence of a semigroup of a global dissipative solution, which is defined for each initial value u0∈H1ℝ and depends continuity on it.

In this study, thermo-responsive molecularly imprinted hydrogels (T-MIHs) were developed as an effective potential adsorbent for selectively adsorption phenol from wastewater. During the process, N-isopropyl acrylamide (NIPAm) was used as thermal responsive monomer. The obtained materials were characterized in detail by fourier transform infrared (FT-IR) spectrometer, scanning electron microscope (SEM), and thermo gravimetric analysis (TGA). A series of static adsorption studies were performed to investigate the kinetics, specific adsorption equilibrium, and selective recognition ability of phenol. Reversible adsorption and release of phenol were realized by changing temperatures. Three type of phenols, namely 3-chlorophenols (3-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) were selected as model analytes to evaluate the selective recognition performance of T-MIHs. The T-MIHs have good selectivity, temperature response, and reusability, making them ideal in applying in the controlled separation and release of phenol pollutants.

The dual-functional Ca12Al14O33: Tb3+ and Ca12Al14O33: Sm3+ materials were prepared by the Self-Propagating Combustion Synthesis (SPCS) technology. The structure, morphology and light absorption property were investigated by XRD, FT-IR, UV-Vis DRS and SEM etc. The doping of Tb3+ and Sm3+ ions had not changed cubic structure of Ca12Al14O33 but leaded to the slight lattice dilatation and the red-shifts of absorption peaks/edges. The excitation and emission spectra indicated that Ca12Al14O33: Tb3+ and Ca12Al14O33: Sm3+ are superior green and red luminescent materials, respectively, and it displayed the distinctly refined structure characteristics which had importantly reference value for the energy level investigation of Tb3+ and Sm3+ ions. Meanwhile, Ca12Al14O33: Tb3+ and Ca12Al14O33: Sm3+ also exhibited the improved photocatalytic degradation for removing dye MB compared with bare Ca12Al14O33.

Decision fusion for distributed detection in sensor networks under non-ideal channels is investigated in this paper. Usually, the local decisions are transmitted to the fusion center (FC) and decoded, and a fusion rule is then applied to achieve a global decision. We propose an optimal likelihood ratio test (LRT)-based fusion rule to take the uncertainty of the decoded binary data due to modulation, reception mode and communication channel into account. The average bit error rate (BER) is employed to characterize such an uncertainty. Further, the detection performance is analyzed under both non-identical and identical local detection performance indices. In addition, the performance of the proposed method is compared with the existing optimal and suboptimal LRT fusion rules. The results show that the proposed fusion rule is more robust compared to these existing ones.

The submicrosized imprinted polypropylene microfiltration membrane (SIPM) for salicylic acid (SA) was prepared by water-in-oil emulsion polymerization method and two-dimensional imprinting method based on polypropylene microfiltration membrane with salicylic acid as template molecule, 4-vinyl pyridine as functional monomer, Span 80 as emulsifier, toluene as the oil phase, ethyleneglycol dimethacrylate as cross-linking agent, and 2,2′-azobis (2-methylpropionitrile) as initiator. The structure, morphology, and surface wettability of SIPM were characterized by Raman spectra, contact angle, and scanning electron microscopy. Flux test shows that the submicrosized imprinted spheres on the membrane is beneficial for increasing the membrane flux. Static adsorption experiment indicates that SIPM has a selective rebinding for salicylic acid. Moreover, the adsorption amount of salicylic acid over SIPM increased with properly increasing the amount of imprinted spheres on the SIPM. Permeation experiment shows that transport mechanism for permeation of the salicylic acid and acetylsalicylic acid toward SIPM is accordance with the facilitated mechanism.

TiO2/Ag bilayer films sputtered onto a 2D polystyrene (PS) bead array in a magnetron sputtering system were found to form a nanocap-shaped nanostructure composed of a TiO2-Ag composite on each PS bead, in which the Ag nanoparticles were trapped partially or fully in the TiO2 matrix, depending on the TiO2 thickness. X-ray Photoelectron Spectroscopy (XPS) results showed the opposite shifts of binding energy for Ti 2p and Ag 3d, indicating the transfer of electrons from metallic Ag to TiO2 owing to the Ag-O-TiO2 composite formation. UV-Vis absorption spectra showed the blue shifts of the surface plasma resonance peaks, and the maximum absorption peak intensity was obtained for TiO2 at 30 nm. The surface-enhanced Raman scattering (SERS) peak intensity first increased and then decreased when the TiO2 thickness changed. The observations of SERS, XPS, and UV-Vis absorption spectra were explained by the dependency of the charge-transfer process on TiO2 thickness, which was ascribed to the changing dielectric properties in the metal/semiconductor system.

The energy reading has been an efficient and attractive measure for collaborative acoustic source localization in practical application due to its cost saving in both energy and computation capability. The maximum likelihood problems by fusing received acoustic energy readings transmitted from local sensors are derived. Aiming to efficiently solve the nonconvex objective of the optimization problem, we present an approximate estimator of the original problem. Then, a direct norm relaxation and semidefinite relaxation, respectively, are utilized to derive the second-order cone programming, semidefinite programming or mixture of them for both cases of sensor self-location and source localization. Furthermore, by taking the colored energy reading noise into account, several minimax optimization problems are formulated, which are also relaxed via the direct norm relaxation and semidefinite relaxation respectively into convex optimization problems. Performance comparison with the existing acoustic energy-based source localization methods is given, where the results show the validity of our proposed methods.

An effective method for the selective separation of dibenzothiophene (DBT) from gasoline samples using a magnetic molecularly imprinted polymer (MMIP) is described. The novel MMIP was synthesized by suspension polymerization using DBT as template. The morphology, magnetic and adsorption properties of MMIP were characterized by Fourier transmission infrared spectrometry, scanning electron microscopy, magnetic measurements, thermogravimetric analysis and nitrogen adsorption. Isothermal absorption of DBT, kinetics of absorption and adsorption selectivity on MMIP were then evaluated. Experimental results show that the adsorption behaviours of MMIP were well-described by the Freundlich isotherm and the pseudo-second-order kinetics. In addition, the synthesized adsorbent (MMIP) exhibited favourable affinity and selectivity for DBT over other competitive compounds.

The time delay of arrival- (TDOA-) based source localization using a wireless sensor network has been considered in this paper. The maximum likelihood estimate (MLE) is formulated by taking the correlated TDOA noise into account, which is caused by the difference with the TOA of the reference sensor. The global optimal solution is difficult to obtain due to the nonconvex nature of the ML function. We propose an alternative semidefinite programming method, which transforms the original ML problem into a convex one by relaxing nonconvex equalities into convex matrix inequalities. In addition, the source localization algorithm in the presence of sensor location errors and non-line-of-sight (NLOS) observations is developed. Our simulation results demonstrate the potential advantages of the proposed method. Furthermore, the proposed source localization algorithm by taking the NLOS TOA measurements as the constraints of the convex problem can provide a good estimate.

Highly effective magnetic molecularly imprinted polymer (MMIP) beads for adsorption of 2,4,6-trichlorophenol (2,4,6-TCP) were synthesized by suspension polymerization. The effect of various parameters such as bed depths (0.6, 1.1 and 1.7 cm), flow rate (1, 2 and 3 ml minute −1 ), influent 2,4,6-TCP concentrations (50, 100 and 200 mg l −1 ), influent solution pH (4, 6 and 8) and temperature (288, 298 and 308 K) was investigated. The breakthrough time increased with the increase of the bed depth, but decreased with an increase of the initial concentration, flow rate and temperature. The Adams–Bohart and Thomas models were applied to the adsorption process under experimental conditions to predict the breakthrough curves for process design. The Thomas model was in good agreement with the experimental data. Compared with magnetic non-imprinted polymers, MMIPs exhibited an excellent selectivity towards 2,4,6-TCP.

In this study, a magnetically separable adsorbent [chitosan (CTS)/kaolin/Fe 3 O 4 magnetic microspheres] was prepared by emulsion crosslinking. The prepared microspheres were characterized by Fourier transform infrared spectroscopic analysis, vibrating sample magnetometry, X-ray diffraction, transmission electron microscopy, energy-dispersive spectrometry, thermogravimetric analysis and scanning electron microscopy. The synthesized microspheres were used as adsorbents for the removal of ciprofloxacin (CIP) from an aqueous solution. Adsorption of CIP from the aqueous solution was investigated in terms of adsorbent dose, initial pH (pH 0 ) and initial concentration. The optimal pH 0 for CIP adsorption was found to be 6. Highest adsorption capacity was achieved with an adsorbent dose of 15 mg. The adsorption kinetics were well described by the pseudo-second-order equation and the adsorption isotherms were fitted to the Langmuir model. Reusability experiments using CTS/kaolin/Fe 3 O 4 magnetic microspheres showed that the adsorption capacity of these microspheres had no observable deterioration in performance even after four repeated cycles. Results of the adsorption–desorption experiments suggest that CTS/kaolin/Fe 3 O 4 microspheres can be used as promising adsorbents for removing CIP from wastewater.

A potassium tetratitanate–based molecularly imprinted polymer (MIP) was prepared by surface molecule–imprinting technique, which involves coating potassium tetratitanate whiskers with silica and modification with 3-methacryloxypropyltrimethoxysilane. The structural properties of the synthesized MIP were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, nitrogen adsorption and scanning electron microscopy. Adsorption behaviour studies were conducted on the prepared MIP, the results of which showed that it has a porous and large surface area. In addition, the prepared MIP showed good adsorptive capacity and selectivity for dibenzothiophene; the adsorption equilibrium time was 180 minutes and the equilibrium adsorption capacity was 20.86 mg/g at 318 K. The adsorptive behaviour followed the Lagergren pseudo-second-order kinetic model and the Freundlich isotherm model. Thermodynamic parameters demonstrated that the adsorption process was spontaneous and endothermic. Thus, based on the study results it can be concluded that the synthesized adsorbent (i.e. MIP) has potential applications for deep desulphurization of gasoline.

Poly(styrene–divinylbenzene)/Fe 3 O 4 (Fe 3 O 4 @St–DVB) magnetic porous polymer microspheres based on suspension polymerization were prepared for adsorption of 2, 4-dichlorophenol (2, 4-DCP) and 2, 6-dichlorophenol (2, 6-DCP) from aqueous solution. The as-prepared product was characterized by Fourier transform infrared spectroscopy, Raman, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis and elemental analysis. The results showed that the composite material has both porous and magnetic characteristics, which aid in faster separation and increase in adsorption capacity. The adsorption performance of the Fe 3 O 4 @(St–DVB) magnetic porous microspheres was manifested by batch mode adsorption experiments with respect to pH, initial concentration, contact time and temperature. The adsorbent was found to be sensitive to changes in pH, and the adsorption capacity of 2, 4-DCP is higher than that of 2, 6-DCP. The kinetics experimental data fitted well with the pseudo-second-order model, as three steps belonged to the pseudo-second-order adsorption process. The adsorption isotherms were also described by the Langmuir and Freundlich isotherm models, respectively. It was found that the Langmuir isotherm model fitted the equilibrium data superior to the Freundlich model. Thermodynamic parameters were calculated by the Gibbs free energy function, confirming that adsorption process was spontaneous and endothermic. In addition, the reusability performance of the Fe 3 O 4 @(St–DVB) magnetic porous microspheres was demonstrated by four repeated cycles.

Herein, we explain an effective method for the synthesis of halloysite/CoFe 2 O 4 magnetic composites (magnetic halloysite nanotubes or MHNTs) and their use as as adsorbents to effectively remove tetracycline hydrochloride (TC–HCl) from aqueous solutions. The synthesized composites were characterized by the following methods: Fourier transform infrared, X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry and atomic absorption spectrometry. Our study results indicated that MHNTs have strong magnetic (Ms = 34.02 emu/g) and low leakage properties. The adsorption capacities of MHNTs were investigated by performing a series of experiments with different pH, temperatures, initial concentrations and reaction time. The Langmuir isotherm model fitted to equilibrium data better than the Freundlich model. The kinetic properties of the composites were well-described by applying the pseudo-second-order equation. Even after carrying out two repeated experimental cycles, the reusability of the synthesized composites did not obviously degenerate.

A highly selective imprinted amino-functionalized Fe 3 O 4 @SiO 2 sorbent was prepared by surface molecular imprinting technique for selective removal of trace 2,4-dichlorophenol (2,4-DCP) in water samples. The 2,4-DCP-imprinted amino-functionalized Fe 3 O 4 @SiO 2 sorbent was characterized by Fourier transform infrared, transmission electron microscopy, vibrating sample magnetometer, thermogravimetric analysis and batch-mode binding studies. The imprinted functionalized Fe 3 O 4 @SiO 2 sorbent exhibited high selectivity and offered a fast kinetics for the adsorption of 2,4-DCP. The prepared sorbent was shown to be promising for selective removal of trace levels of 2,4-DCP in environmental water samples.

The freeze-dried biomass of Paecilomyces lilacinus was employed as a biosorbent for the removal of silver ions from aqueous solution. The effects of factors such as the solution pH, the initial Ag(I) ion concentration, contact time and temperature were examined. Maximum Ag(I) adsorption was obtained at pH 3.0. The pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic models were fitted to the experimental data when it was found that such data were best fitted by the pseudo-second-order kinetic model. The equilibrium experimental data were well fitted by the Langmuir model (R 2 > 0.995) and the maximum biosorption capacity at 298 K was 101.0 mmol/g. Thermodynamic parameters such as the Gibbs' free energy, ΔG 0 , the standard enthalpy, ΔH 0 , and the standard entropy, ΔS 0 , were evaluated. The results indicated that the biosorption of Ag(I) ions onto P. lilacinus biomass was spontaneous and endothermic in nature. The FT-IR analysis results indicated that amine, carboxylic and hydroxyl groups were involved in the biosorption process.

Raw palygorskite was modified by the addition of selected surfactants, viz. hexadecyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB) and octadecyldimethylbenzyl ammonium chloride (ODBAC). These modified clays were used as sorbents for the adsorptive removal of 2,6-dichlorophenol (2,6-DCP) from aqueous solution. Characterization of the sorbents was achieved by Fourier-transform infrared (FT-IR) analysis, nitrogen adsorption/desorption measurements and particle-size analysis. The adsorptive performance of the modified palygorskites towards the removal of 2,6-DCP from aqueous solution was studied by batch methods. In addition, the influence of contact time, pH and temperature on the adsorption process was investigated in detail. The equilibrium data for the three modified sorbents were well fitted by the Langmuir model. It was found that the monolayer adsorption capacity increased with increasing contact time and solution temperature, respectively. Application of the pseudo-first-order and pseudo-second-order kinetic models to the kinetic data showed that the pseudo-second-order kinetic model provided an excellent fit (R 2 > 0.99). In addition, the film diffusion, pore diffusion and intra-particle diffusion models were also used to investigate the adsorption mechanism. Intra-particle diffusional analysis indicated that 2,6-DCP molecules diffused rapidly during the initial adsorption stage, followed by a slower stage and finally the establishment of an equilibrium condition. Thermodynamic studies showed that the adsorption of 2,6-DCP onto the three sorbents examined occurred spontaneously and that the process was endothermic in nature. The results indicate that the surfactant-modified palygorskite exhibited a significant potential as a sorbent material for the removal of phenolic compounds from aqueous solution.

A novel surface-imprinting polymer (MIP/K 2 Ti 6 O 13 ) was prepared using potassium hexatitanate whiskers (K 2 Ti 6 O 13 ) as the carrier employing electrostatic interaction and π–π interaction between the template molecule [dibenzothiophene (DBT)] and the functional monomer [4-vinylpyridine (4VP)]. The synthetic polymer was characterized via Fourier-transform infrared (FT-IR) spectroscopy, surface area and porosity analysis, and X-ray diffraction (XRD). Static adsorption experiments were conducted to evaluate the adsorption kinetics, adsorption isotherms and adsorption selectivity of MIP/K 2 Ti 6 O 13 . Adsorption kinetic studies revealed that a contact time of 300 min was necessary to attain equilibrium. Adsorption isotherm studies indicated that the capacity of MIP/K 2 Ti 6 O 13 towards the adsorption of DBT at 298 K, 308 K and 318 K was 16.18 mg/g, 22.74 mg/g and 29.89 mg/g, respectively. Selectivity experiments showed that the adsorption capacity of DBT on MIP/K 2 Ti 6 O 13 was greater than for the other three analogues, while the imprinting factor towards DBT (α) was 2.06.

Surface ion-imprinting technology was applied to prepare a new Sr(II) ion-imprinted polymer [Sr(II)-IP] by grafting chitosan-Sr(II) onto potassium titanate whiskers. The imprinting mechanism of the prepared polymer was examined, using infrared spectroscopy (IR), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The effects of pH and contact time were examined, together with the adsorption capacity and selectivity of the imprinted polymer. The adsorption isotherms could be fitted by the Langmuir model, with the dimensionless separation factor R L indicated favourable adsorption. In addition, the kinetic data were fitted more closely by the pseudo-second-order kinetic model rather than the pseudo-first-order model. The values of the Gibbs' free energy (ΔG 0 ), standard entropy (ΔS 0 ) and standard enthalpy (ΔH 0 ) calculated from the adsorption data suggested that the adsorption of Sr(II) onto Sr(II)-IP was a spontaneous and endothermic process. The relative selectivity coefficients of Sr(II)-IP for Sr(II)/Cs(I) at different initial concentrations were 95.8, 320 and 1428.6, respectively, which were far greater than that of the non-imprinted polymer (NIP).

Molecular imprinting has been conducted on the surface of TiO 2 particles to enable the recognition of dibenzothiophene (DBT) molecules. This was achieved via the use of a novel surface molecular-imprinting technique. The adsorption behaviour of the dibenzothiophene-imprinted material (D-MIP/TiO 2 ) was evaluated using batch adsorption experiments to determine the kinetic, isotherm and thermodynamic parameters. The experimental results showed that the adsorption process followed pseudo-second-order kinetics and that the experimental data were well fitted by the Freundlich adsorption equation. This indicated that adsorption involved a multilayer process. Values of the Gibbs' free energy (ΔG 0 ) ranged from −7.11 kJ/mol to −9.36 kJ/mol over the temperature interval 298–318 K, indicating that the adsorption was endothermic in nature. In addition, D-MIP exhibited selective recognition of DBT relative to other similar compounds such as benzothiophene (BT), 4-methyldibenzothiphene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). In the corresponding selectivity test, D-MIP/TiO 2 showed a greater adsorption capacity towards DBT than BT, 4-MDBT and 4,6-DMDBT. The large imprinting factor (ca. 2.5) exhibited by D-MIP/TiO 2 for DBT could be explained in terms of a covalent assembly mechanism.

Novel surface strontium(II) ion-imprinted adsorbent particles have been prepared via the copolymerization of chitosan as the monomer, γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560) as the cross-linking agent and 2,2′-azobisisobutyronitrile (AIBN) as the initiator in the presence of SrCl 2 • 6H 2 O. The prepared imprinted adsorbent was used for the selective solid-phase extraction (SPE) of trace Sr(II) ions in a practical sample prior to its determination by inductively coupled plasma–atomic emission spectrometry (ICP–AES). The results suggest that the adsorption kinetic data accorded better with the pseudo-second-order model, while the adsorption equilibrium data gave a good fit to the Langmuir isotherm equation, yielding a maximum adsorption capacity of 27.58 mg/g and a Langmuir adsorption equilibrium coefficient of 0.0363 ℓ/mg at 298 K. The relative selectivity coefficient values of Sr(II) ion-imprinted particles were several times greater than those for the non-imprinted matrix. The new Sr(II) ion-imprinted micro-beads were successfully applied for the separation of Sr(II) ions from river and clay samples. The detection limit (3σ) for Sr(II) ions as determined by flame atomic absorption spectrometry (FAAS) was 0.21 ng/mℓ. The relative standard deviation (RSD) for the determination of Sr(II) ions was 6–9% over the concentration range 0.03–0.3 mg/ℓ.