Adsorption of lead(II) by silica/cell composites from aqueous solution: kinetic, equilibrium, and thermodynamics studies.

Silica/cell composites were prepared for the adsorption of lead ions, Pb(II), from aqueous solution in a batch system. The silica/cell composites possessed micropores, high surface area, and abundant functional groups. Adsorption performance was investigated by analyzing the effects of such factors as the initial pH, contact time with different initial concentration, and initial Pb(II) concentration at different temperature. The kinetic data were fitted to pseudo-second-order and intraparticle diffusion kinetic models. The results were better fitted by the pseudo-second-order kinetic model. Intraparticle diffusion increased with an increase of initial concentration and the sorption process was controlled by film diffusion. The Langmuir isotherm model was fitted to the experimental data significantly better than Freundlich and Dubinin-Radushkevich isotherm models. The maximum adsorption capacity was 97.10 mg g(-1), according to the Langmuir isotherm model. Thermodynamics parameters confirmed the spontaneous, endothermic, and entropy-gained nature within the studied temperature range (from 298 to 318 K). The composites could be effectively desorbed by the 2.0 mol L(-1) HNO3 solution and would be a potential adsorbent.

Microbe-induced gene silencing boosts crop protection against soil-borne fungal pathogens.

Small RNA (sRNA)-mediated trans-kingdom RNA interference (RNAi) between host and pathogen has been demonstrated and utilized. However, interspecies RNAi in rhizospheric microorganisms remains elusive. In this study, we developed a microbe-induced gene silencing (MIGS) technology by using a rhizospheric beneficial fungus, Trichoderma harzianum, to exploit an RNAi engineering microbe and two soil-borne pathogenic fungi, Verticillium dahliae and Fusarium oxysporum, as RNAi recipients. We first detected the feasibility of MIGS in inducing GFP silencing in V. dahliae. Then by targeting a fungal essential gene, we further demonstrated the effectiveness of MIGS in inhibiting fungal growth and protecting dicotyledon cotton and monocotyledon rice plants against V. dahliae and F. oxysporum. We also showed steerable MIGS specificity based on a selected target sequence. Our data verify interspecies RNAi in rhizospheric fungi and the potential application of MIGS in crop protection. In addition, the in situ propagation of a rhizospheric beneficial microbe would be optimal in ensuring the stability and sustainability of sRNAs, avoiding the use of nanomaterials to carry chemically synthetic sRNAs. Our finding reveals that exploiting MIGS-based biofungicides would offer straightforward design and implementation, without the need of host genetic modification, in crop protection against phytopathogens.

3-Carb-oxy-quinolin-1-ium-2-carboxyl-ate monohydrate.

The title compound, C(11)H(7)NO(4)·H(2)O, contains a 3-carb-oxy-quinolin-1-ium-2-carboxyl-ate (qda) zwitterion and one water mol-ecule. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules into inversion dimers, and these dimers are further connected by O-H⋯O hydrogen bonds into a three-dimensional supra-molecular architecture. In addition, π-π inter-actions occur between pyridine and benzene rings from different qda ligands [centroid-centroid distance = 3.749 (1) Å] and the dihedral angles of the -CO(2)H and -CO(2) groups to the quinoline system are 8.47 (3) and 88.16 (6)°, respectively.

2,2'-Dimethyl-1,1'-[2,2-bis-(bromo-methyl)propane-1,3-di-yl]dibenzimidazole hemihydrate.

The title compound, C(21)H(22)Br(2)N(4)·0.5H(2)O, contains two benzimidazole groups which may provide two potential coordination nodes for the construction of metal-organic frameworks. The mean planes of the two imidazole groups are almost perpendicular, with a dihedral angle of 83.05 (2)°, and adjacent mol-ecules are linked into a one-dimensional chain by π-π stacking inter-actions between imidazole groups of different mol-ecules [centroid-to-centroid distances of 3.834 (2) and 3.522 (2) Å].

cyclo-Tetra-kis{µ-2,2'-dimethyl-1,1'-[2,2-bis-(bromo-meth-yl)propane-1,3-di-yl]di(1H-benzimidazole)-κN:N}tetra-kis-[bromidocopper(I)].

The title compound, [Cu(4)Br(4)(C(21)H(22)Br(2)N(4))(4)], features a macrocyclic Cu(4)L(4) ring system in which each Cu(I) atom is coordinated by one bromide ion and two N atoms from two 2,2'-dimethyl-1,1'-[2,2-bis-(bromo-meth-yl)propane-1,3-di-yl]di(1H-benzimidazole) (L) ligands in a distorted trigonal-planar geometry. The L ligands adopt either a cis or trans configuration. The asymmetric unit contains one half-mol-ecule with the center of the macrocycle located on a crystallographic center of inversion. Each bromide ion binds to a Cu(I) atom in a terminal mode and is oriented outside the ring. The macrocycles are inter-connected into a two-dimensional network by π-π inter-actions between benzimid-azole groups from different rings [centroid-centroid distance = 3.803 (5) Å.

Poly[(µ(2)-quinoline-3-carboxyl-ato-κN:O)(µ(2)-quinoline-3-carboxyl-ato-κN:O,O')cadmium].

In the title compound, [Cd(C(10)H(6)NO(2))(2)](n), the Cd(II) atom is coordinated by three O atoms and two N atoms from four quinoline-3-carboxyl-ate (L(-)) ligands, leading to a distorted trigonal-bipyramidal geometry. The L(-) ligands link the Cd(II) atoms into a plane parallel to (100), with one ligand being tridentate, coordinating via the N atom and chelating a second Cd atom, and the other being bidentate, bridging two Cd atoms via the N and one O atom.. This two-dimensional network extends into a double-layer network by π-π inter-actions, with centroid-centroid distances of 3.680 (2) and 3.752 (2) Å. Another type of π-π inter-action between pyridine rings [centroid-centroid distance = 3.527 (2) Å] leads to a three-dimensional supra-molecular architecture.

Extraction and determination of chloramphenicol in feed water, milk, and honey samples using an ionic liquid/sodium citrate aqueous two-phase system coupled with high-performance liquid chromatography.

A green, simple, non-toxic, and sensitive sample pretreatment procedure coupled with high-performance liquid chromatography (HPLC) was developed for the analysis of chloramphenicol (CAP) that exploits an aqueous two-phase system based on imidazolium ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim]BF(4)) and organic salt (Na(3)C(6)H(5)O(7)) using a liquid-liquid extraction technique. The influence factors on partition behaviors of CAP were studied, including the type and amount of salts, the pH value, the volume of [Bmim]BF(4), and the extraction temperature. Extraction efficiency of the CAP was found to increase with increasing temperature and the volume of [Bmim]BF(4). Thermodynamic studies indicated that hydrophobic interactions were the main driving force, although electrostatic interactions and salting-out effects were also important for the transfer of the CAP. Under the optimal conditions, 90.1% of the CAP could be extracted into the ionic liquid-rich phase in a single-step extraction. This method was practical when applied to the analysis of CAP in feed water, milk, and honey samples with a linear range of 2~1,000 ng mL(-1). The method yielded a limit of detection of 0.3 ng mL(-1) and a limit of quantification of 1.0 ng mL(-1). The recovery of CAP was 90.4-102.7% from aqueous samples of real feed water, milk, and honey samples by the proposed method. This novel process is much simpler and more environmentally friendly and is suggested to have important applications for the separation of antibiotics.

Biosorption of Pb(II) by biomass of KC-2: kinetic, equilibrium and characteristic studies.

Performance and characteristics of biosorption of Pb(II) had been studied in a batch system using the fungal strain biomass, KC-2. The biosorption performance was investigated by analysing the effects of such factors as the initial pH, initial Pb(II) concentration, and contact time at 303 K. The maximum Pb(II) adsorption was obtained at pH 5.0. The experimental data were described by the pseudo first-order, pseudo second-order and intraparticle diffusion kinetic models, and were closely followed the pseudo second-order kinetic model. The equilibrium experimental data were well fitted to Langmuir model and the maximum biosorption capacity was 84.03 mg g(-1). The adsorption mechanism was examined by FTIR, SEM and EDAX analysis. Results indicated that carboxylic, hydroxyl and amine groups were involved in the biosorption and ion exchange mechanism existed.

Poly[[µ(2)-2,2'-diethyl-1,1'-(butane-1,4-di-yl)diimidazole-κN:N](µ(2)-5-hydroxy-isophthalato-κO:O)zinc].

In the title coordination polymer, [Zn(C(8)H(4)O(5))(C(14)H(22)N(4))](n), the Zn(II) cation is coordinated by an O(2)N(2) donor set in a distorted tetra-hedral geometry. The Zn(II) ions are linked by µ(2)-OH-bdc (OH-H(2)bdc = 5-hy-droxy-isophthalic acid) and bbie ligands [bbie = 2,2'-diethyl-1,1'-(butane-1,4-di-yl)diimidazole], forming a two-dimensional layer parallel to the ab plane. The layers are further connected through intermolecular C-H⋯O and O-H⋯O hydrogen bonds, forming a three-dimensional supramolecular structure. In the bbie ligand, the two C atoms in the ethyl group are each disordered over two positions with a site-occupancy ratio of 0.69:0.31.

Poly[[µ-2,2'-diethyl-1,1'-(propane-1,3-di-yl)di-1H-imidazole-κN:N](µ-5-hy-droxy-isophthalato-κO:O)zinc].

In the title coordination polymer, [Zn(C(8)H(4)O(5))(C(13)H(20)N(4))](n), the Zn(II) ion is coordinated by an O(2)N(2) donor set in a distorted tetra-hedral geometry. The Zn(II) ions are connected by 5-hy-droxy-isophthalate (hbdc) and 2,2'-diethyl-1,1'-(propane-1,3-di-yl)di-1H-imidazole (pbie) ligands, forming a threefold inter-penetrating diamondoid framework. In the pbie ligand, one of the ethyl-imidazole groups is disordered over two positions, with a site-occupancy ratio of 0.670 (9):0.330 (9). An inter-molecular O-H⋯O hydrogen bond is formed between the hy-droxy and carboxyl-ate groups of the hbdc ligands.

Poly[[diaqua-bis-(µ(3)-3-carboxyl-ato-4-hy-droxy-benzene-sulfonato)-tri-µ(2)-pyrazine-tetra-silver(I)] dihydrate].

The title coordination polymer, {[Ag(4)(C(7)H(4)O(6)S)(2)(C(4)H(4)N(2))(3)(H(2)O)(2)]·2H(2)O}(n), contains two independent Ag(I) ions. One Ag(I) ion is coordinated by one O atom from a 3-carboxyl-ato-4-hy-droxy-benzene-sulfonate (L) ligand, two N atoms from two pyrazine ligands and a water mol-ecule. The other Ag(I) ion is coordinated by two O atoms from two L ligands and one N atom from a pyrazine ligand. One of the pyrazine ligands lies on an inversion center. The L and pyrazine ligands link the Ag(I) ions into polymeric layers parallel to the ac plane. The layers are connected by inter-molecular O-H⋯O hydrogen bonds. An intra-molecular O-H⋯O hydrogen bond is also present in the L ligand.

[Studies on TCs-Fe(III) system separation/enrichment of trace tetracyclines antibiotic by combination ionic liquid [Hmim]PF6 solvent sublation with fluorescence spectroscopy determination].

It is the first time ionic liquid was applied to gas solvent sublation, which established a new method for separation/enrichment of tetracyclines (TCs) antibiotic based on ionic liquid gas solvent sublation. The optimizing experimental conditions were as follows: the mixture of ionic liquid 1-hexyl-3-methylimidazo lium hexafluorophosphats and ethyl acetate ([Hmim] PF6-EA, phi = 1/0.9) can be used as flotation solvent, Fe(III) ion was as trapping agent, pH of test solution was 7.6, the gas flow rate was 40 mL x min(-1), and the flotation time was 50 min. The complexes of TCs- Fe (III) were pre-concentrated in the [Hmim] PF6-EA layer and this was used to determine analytes by fluorescence method directly. The linear regression equation was F = 246.5c+4.32 (c: microg x 10 mL(-1)), and correlation coefficient was 0.999 1. Recoveries between 94.2% and 100.4% were achieved from surface water and sediment samples in ponder by using this method and the relative standard deviation of 5 microg x mL(-1) TCs for 5 parallel determinations was less than 3.2%. FTIR spectroscopy demonstrated that no chemical (bonding) interactions occurred between the ionic liquid and the complexes functional groups, and the ionic liquid was only solvent. The experimental result indicated that utilizing ionic liquid to float TCs in environmental sample is feasible.

[Analysis of properties of cadmium adsorption onto whisker surface ion-imprinted polymer by inductively coupled plasma atomic emission spectrometry].

A new type of surface ion-imprinted polymer was synthesized in aqueous media with sodium trititanate whisker in the presence of Cd(II), chitosan and gamma-glycidoxypropyl trimethoxysilane (KH-560). A batch of adsorption experiments were performed to evaluate its adsorption of Cd(II) using inductively coupled plasma atomic emission spectrometry (ICP-AES). The factors affecting adsorption capacity, including pH and sorbent amount, were discussed. The adsorption kinetics and adsorption isothermals were also obtained. The Langmuir isotherm can fit in the experimental equilibrium data. Under the optimum conditions, the value of the adsorption was above 99%, and the maximum adsorption capacity was 52.34 mg x g(-1). In accordance with the parameters distribution coefficient (K(d)) and selectivity coefficient (K), the selectivity for Cd(II) of the prepared imprinted polymer was estimated. Finally, the adsorption mechanism was discussed and the detection limit of 0.024 microg x mL(-1) with the relative standard deviation (RSD) of 1.74% (c = 1.0 microg x mL(-1), n = 13) for Cd(II) was obtained. Results showed that the surface Cd(II)-imprinted polymer was a solid sorbent with high efficiency, low-cost, convenient separation/enrichment for environmental trace Cd(II).

Poly[triaqua-(µ-butane-1,2,3,4-tetra-carboxyl-ato)dicadmium(II)].

The asymmetric unit of the title Cd(II) coordination polymer, [Cd(2)(C(8)H(6)O(8))(H(2)O)(3)](n), contains two crystallographically independent Cd(II) cations, one-half each of two independent anionic butane-1,2,3,4-tetra-carboxyl-ate units (L) and three water mol-ecules. Both anionic units lie on inversion centers. One of the Cd(II) ions is six-coordinated by four carboxyl-ate O atoms from four L anions and two water O atoms in a distorted octa-hedral coordination environment. The other Cd(II) ion is eight-coordinated by seven carboxyl-ate O atoms from four L anions and one water O atom. The anionic units bridge neighboring Cd(II) centers, forming a three-dimensional framework. O-H⋯O hydrogen-bonding inter-actions between the water mol-ecules and carboxyl-ate O atoms further stabilize the structure.

Aqua-(2-hydr-oxy-5-sulfonatobenzoato-κO)bis-(2-phenyl-1H-1,3,7,8-tetra-aza-cyclo-penta-[l]phenanthrene-κN,N)zinc(II).

In the title compound, [Zn(C(7)H(4)O(6)S)(C(19)H(12)N(4))(2)(H(2)O)], the Zn(II) ion is coordinated by two N,N'-bidentate 2-phenyl-1H-1,3,7,8-tetra-azacyclo-penta-[l]phenanthrene ligands, one O-monodentate 5-sulfosalicylate dianion and a water mol-ecule. This results in a distorted cis-ZnO(2)N(4) octa-hedral coordination geometry for the metal ion. In the crystal, mol-ecules are expanded into a three-dimensional supra-molecular motif via O-H⋯O, O-H⋯N and N-H⋯(O,S) hydrogen bonds. In addition, π-π stacking inter-actions between the aromatic rings of the polycyclic ligands consolidate the sturcture [shortest centroid-centroid distance = 3.501 (2) Å].

[ICP-AES determination of Cu2+, Pb2+ and Cd2+ with adsorption behavior of potassium hexatitanate whisker].

A new method for the determination of free Cu2+, Pb2+ and Cd2+ in environmental sample using potassium hexatitanate whisker as a solid-phase extractant and inductively coupled plasma-atomic emission spectrometry (ICP-AES) as a sensitive detector has been developed. The adsorption rate of Cu2+, Pb2+ and Cd2+ by potassium hexatitanate whisker was 98% at pH 5.0, and Cu2+, Pb2+ and Cd2+ could be eluted from potassium hexatitanate whisker with HNO3 (C: 3 mol x L(-1)). The Cu2+, Pb2+ and Cd2+ in environmental samples were preconcentrated with potassium hexatitanate whisker and determined by ICP-AES, the detection limits of Cu2+, Pb2+ and Cd2+ (3sigma, n = 9) were 0.007 1, 0.006 8 and 0.007 1 microg x mL(-1), and the relative standard deviations (RSD) were 0.63%, 0.61% and 0.50%, respectively. The method was applied to the determination of analytes in real samples, such as chrysanthemum and loquat leaf. And good results were obtained (recoveries were 90%-102.9%). The results obtained indicate that the potassium hexatitanate whisker has good regenerate capability.

[Flame atomic absorption spectrometry determination of cadmium in environmental water with preconcentration and separation by sodium trititanate whisker].

Sodium tertitanate whisker is a new material for preconcentration. The adsorption properties of sodiium trititanate whisker for Cd(II) were studied and a new method for preconcentration and separation of Cd(II) was proposed. The adsorption rate of Cd(II) by sodium trititanate whisker was 98% at pH 5.0 and Cd(II) could be eluted from sodium trititanate whisker with hydrochloric acid (C: 0.1 mol x L(-1)). The Cd(II) in environmental water was preconcentrated with sodium trititanate whisker and determined by flame atomic absorption spectrometry (FAAS). The detection limit (3sigma, n = 9) was 3.1 ng x L(-1), and the relative standard deviation (RSD) was 2.6%. The response of proposed method is linear in the concentration range of 0.01-1.0 microg x mL(-1) of Cd(II). The method was applied to the determination of analytes in real samples, such as Changjiang River water, Canal water, Yudai River water etc. Good results were obtained (relative standard deviations were 1.5%-4.7%, while recoveries were 98%-102.0%).

[Study on the adsorption behavior of nickel on potassium tetratitanate whisker by flame atomic absorption spectrometry].

The adsorption behavior of Ni (II) on potassium tetratitanate whisker was studied systemically by FAAS, seeing about the reasons for absorption, disentanglement and the effect of interfering ions on the recovery. The preconcentration method was simple, quick and had good selectivity. The adsorption rate of Ni(II) by potassium tetratitanate whisker was 100% at pH 5.0 and Ni(II) could be eluted from potassium tetratitanate whisker with hydrochloric acid (C: 0.5 mol x L(-1)), shake time exceeding 5 min, stick time exceeding 1.5 h, and the disentanglement ratio exceeding 90%. The relative standard deviation (RSD) was 2.6%. The results obtained indicate that the potassium tetratitanate whisker has good regenerate capability.

Molecularly imprinted Ag/Ag3VO4/g-C3N4 Z-scheme photocatalysts for enhanced preferential removal of tetracycline.

High selectivity and fast charge separation are two important factors for photocatalytic wastewater treatment. Herein, we prepared a molecular imprinted Ag/Ag3VO4/g-C3N4 photocatalyst (MIP) that exhibited great specific recognition ability along with excellent photocatalytic activity. The ultrathin g-C3N4 nanosheets with high surface are used to prepare. The Z-scheme Ag3VO4/g-C3N4 heterostructure and the surface plasmon resonance of the photoreduced Ag0 together contributed to the improvement of the separation efficiency of photogenerated electrons and holes. In addition, MIP provides the specific recognition ability to preferentially adsorb the target pollutant. The selectivity of photocatalysis was evaluated by the degradation of oxytetracycline and tetracycline solutions. Photoluminescence and transient photocurrent measurements further prove the improved charge separation efficiency of MIP. A plausible photocatalytic reaction mechanism is proposed based on electron spin resonance measurement and the active species trapping experiments, where indicates that the main active species of this photocatalytic process are O2- and h+. This research provides an effective strategy for the simultaneous enhancement of selectivity and activity via molecular imprinting.

An efficient motion-resistant method for wearable pulse oximeter.

Reduction of motion artifact and power saving are crucial in designing a wearable pulse oximeter for long-term telemedicine application. In this paper, a novel algorithm, minimum correlation discrete saturation transform (MCDST) has been developed for the estimation of arterial oxygen saturation (SaO2), based on an optical model derived from photon diffusion analysis. The simulation shows that the new algorithm MCDST is more robust under low SNRs than the clinically verified motion-resistant algorithm discrete saturation transform (DST). Further, the experiment with different severity of motions demonstrates that MCDST has a slightly better performance than DST algorithm. Moreover, MCDST is more computationally efficient than DST because the former uses linear algebra instead of the time-consuming adaptive filter used by latter, which indicates that MCDST can reduce the required power consumption and circuit complexity of the implementation. This is vital for wearable devices, where the physical size and long battery life are crucial.