Qualitative and quantitative adsorption mechanisms of zinc ions from aqueous solutions onto dead carp derived biochar.

The objective of this study is to investigate the qualitative mechanisms of Zn2+ adsorption on carp biochars (CMBx) produced from dead carp at different temperatures (450-650 °C) and their quantitative contribution. The pseudo second order kinetic model and the Langmuir model could fit the kinetic and isothermal adsorption data well, respectively. The intra-particle diffusion was the main rate-limiting step but not the only rate-limiting step. The maximum adsorption capacity obtained from the Langmuir model for CMB650 was 87.7 mg g-1 which was greater than those of other biochars. Precipitation with minerals, ion exchange, and complexation with functional groups (OFGs) were the main adsorption mechanisms. Quantum chemistry calculations confirmed that the functional groups (e.g., hydroxyl, carboxyl and C[double bond, length as m-dash]C) tended to bind with Zn2+ more strongly than with Ca2+ and Mg2+, because the structure of the complex formed by the former was more stable. The contribution of different adsorption mechanisms varied with the pyrolysis temperature to prepare biochar. With increasing pyrolysis temperature, the contribution of the interaction between Zn2+ and the minerals increased from 46.4% to 84.7%, while that of complexation with OFGs decreased from 41.7% to 4.7%. Overall, the mechanism of Zn2+ adsorption on CMB450 was dominated by complexation with OFGs and exchange with cations (accounting for 73.2%), while the mechanisms on CMB650 were dominated by the interaction with minerals. In view of the total adsorption capacity, 650 °C was the optimized pyrolysis temperature for CMBx preparation and adsorption treatment of Zn-contaminated water. These results are useful for screening effective biochars as engineered sorbents to treat Zn-containing wastewater.

[Sorption of p-Nitrophenol by Biochars of Corncob Prepared at Different Pyrolysis Temperatures].

Sorption of p-nitrophenol (PNP) on biochars prepared from pyrolysis of corncob in the temperature range of 200-600℃ (CC200-CC600) was investigated. Sorption mechanisms were discussed. Pyrolysis temperature showed a pronounced effect on properties of biochars. Decreases in molar H/C, O/C and (O+N)/C ratios were resulted from removal of H- and O-containing functional groups with increasing pyrolysis temperature, and produced biochars with low polarity and high aromaticity. The isotherms data were well described by the Freundlich model. Batch sorption experiments showed that the PNP sorption was strongly dependent on the properties of biochars. A linear relationship was observed between sorption parameters (n and KF) and properties of biochars such as molar elemental ratios[H/C, O/C, and (O+N)/C]. The sorption and partition fractions were quantified by isotherm separation method. PNP sorption on biochar produced at 200℃ was linear due to partition on uncarbonized organic matter in biochar, while PNP sorption on biochars produced at 300-600℃ was nonlinear and adsorption-dominant for all the biochars via π-π electron donor-acceptor interaction and pore-filling.

[Ammonium Adsorption Characteristics in Aqueous Solution by Dairy Manure Biochar].

The adsorption characteristics of ammonium from aqueous solution onto biochar derived from dairy manure were investigated as a function of parameters such as solution pH, particle size, adsorbent dosage, temperature and competitive cations. The results indicated that the effects of other cations on the adsorption of ammonium followed the order of preference Na > Ca2+ at identical mass concentrations. It was observed that pH played an important role in the ammonium adsorption and the optimal pH values ranged between 5 and 8. The kinetic data fitted the pseudo-second-order model (R2 = 0.967 3) but showed very poor fits for the pseudo-first-order model (R2 = 0.765 9) and the Elovich model (R2 = 0.724 9). The results from the Intra-particle model also showed that there were two separate stages in sorption process, which were external diffusion and the diffusion of inter-particle. Adsorption isotherms for dairy manure biochar were fitted the Freundlich model (R2 = 0.976 2) more effectively than other models. Thermodynamics parameters such as free energy (ΔGθ), enthalpy (ΔHθ), and entropy (ΔSθ) were also determined, which indicated that the adsorption was a spontaneous and endothermic process.

[Fourier Transform Spectrometer Based on Rotating Parallel-Mirror-Pair].

In the temporally-modulated Fourier transform spectroscopy, the translational moving mirror is difficult to drive accurately, causing tilt and shear problems. While, a rotational moving mirror can solve these problems. A rotary Fourier transform spectrometer is recommanded in this paper. Its principle is analyzed and the optical path difference is deduced. Also, the constrains for engineering realization are presented. This spectrometer consists of one beamsplitter, two fixed mirrors, one rotating parallel mirror pair, a collimating lens, a collecting lens, and one detector. From it's principle, this spectrometer show a simple structure, and it is assembled and adjustmented easily because the two split light are interfered with each other after reflected through the same plane mirror; By calculating the expression of it's optical path difference, the spectrometer is easy to realize large optical path difference, meaning high spectral resolution; Through analyzing it's engineering design constraints and computer simulation, it is known that the spectrometer should get the high resolution sample by high-speed spinning motor, so it is easy to achieve precise motion control, good stability, fast measurement speed.

[Multi-DSP parallel processing technique of hyperspectral RX anomaly detection].

To satisfy the requirement of high speed, real-time and mass data storage etc. for RX anomaly detection of hyperspectral image data, the present paper proposes a solution of multi-DSP parallel processing system for hyperspectral image based on CPCI Express standard bus architecture. Hardware topological architecture of the system combines the tight coupling of four DSPs sharing data bus and memory unit with the interconnection of Link ports. On this hardware platform, by assigning parallel processing task for each DSP in consideration of the spectrum RX anomaly detection algorithm and the feature of 3D data in the spectral image, a 4DSP parallel processing technique which computes and solves the mean matrix and covariance matrix of the whole image by spatially partitioning the image is proposed. The experiment result shows that, in the case of equivalent detective effect, it can reach the time efficiency 4 times higher than single DSP process with the 4-DSP parallel processing technique of RX anomaly detection algorithm proposed by this paper, which makes a breakthrough in the constraints to the huge data image processing of DSP's internal storage capacity, meanwhile well meeting the demands of the spectral data in real-time processing.

[Impact and improvement of the mechanical shutter on large-array filter-type multispectral imaging system].

The present paper analyzes the impact of mechanical shutter on the spectral image acquisition and processing of large-array filter-type multispectral imaging system. The final image quality relies highly on the mechanical shutter due to the fluctuation at exposure time. The conventional mechanical shutter's structure and driving method was analyzed to find out the key fact for its poor stability. An improved method of mechanical transmission and circuit driving was proposed. Laboratory experiments showed that with the improved design strategy, the maximum rate of change between adjacent exposures was reduced from 15.05% to 0.96%, which is a great improvement of the exposure time stability. Field test was also carried out and the results show that the combined color images are closer to the realistic targets and no abrupt color change iwas found. It's of great significance for practical application in multispectral image process, interpretation and target identification.

[Sorption behavior of Triton X-100 on loess and affecting factors].

Batch experiments involving soil-aqueous systems were conducted to determine sorption of Triton X-100 onto natural loess as a function of equilibrium time, Triton X-100 concentration, ionic strength, and pH value. The results showed that the equilibration time for sorption of Triton X-100 onto loess was about 30 min. The sorption kinetics of Triton X-100 fitted well to the pseudo-first-order kinetic model and the corresponding parameters Q(e), k1, and r2 were 3.041 mg x g(-1), 0.102 min(-1), and 0.9934, respectively. Sorption isotherm was found to be distinctly nonlinear. The Sips model provided the best fitting to the experimental data among the four isothermal models tested. Q(max) and r2 of Sips model were 3.202 mg x g(-1) and 0.998 7, respectively. It was found that the ionic strength and the pH of the solution had a significant influence on the sorption of Triton X-100 onto loess. The amount of Triton X-100 sorbed onto the loess increased significantly with increasing concentration of NaCl. Sorption of Triton X-100 onto loess was influenced greatly by pH, the amount of Triton X-100 sorbed decreased as the pH increased.

[Remediation of Cu/phenanthrene and combined contaminated loess soil by chemical-enhanced washing].

The chemical-enhanced washing of Cu2+ or/and phenanthrene (PHE) single or combined contaminated loess soil in Gansu Province was investigated with disodium ethylene diamine tetraacetate (EDTA) or/and sodium dodecyl sulfate (SDS) by the batch equilibrium experiments. The experimental results showed that EDTA or/and SDS could remove efficiently Cu2+ and/or PHE in single-contaminated or combined contaminated loess soils. The Cu2+ removal was significantly promoted by coexisting PHE with low concentration of EDTA (EDTA < 0.1 mol/L), however, the removal was slightly hindered with high concentration of EDTA (EDTA > 0.1 mol/L). As for the PHE removal by EDTA, it was founded that coexisting Cu2+ could enhance the PHE removal in the investigated ranges of the concentrations of EDTA. When concentration of EDTA was 0.01 mol/L, the removal of combined PHE was 20.94% higher than that of single PHE. The experimental results of the removal of contaminations by SDS showed that coexisting Cu2+ could suppress slightly the removal of PHE at a concentration of less than 4 000 mg/L SDS, but could assist the removal of PHE in 5 000 mg/L or higher SDS concentration. On the contrary, the influence of coexisting PHE for the removal of Cu2+ by SDS was that it facilitated Cu2+ extraction by low concentrations of SDS, however, it inhibited the removal of Cu2+ at high concentrations of SDS. The removal efficiencies of PHE and Cu2+ were improved greatly as using combined EDTA-SDS. Beside, there are some differences in the removal efficiency of the oth contaminants with the different sequence of EDTA and SDS added in the washing solution. In EDTA washing followed by SDS, SDS washing followed by EDTA and mixture of SDS-EDTA washing concurrently, the removal of Cu2+ is 91.40%, 95.10% and 96.50%, respectively, which is 28.46%, 32.16%, 33.56% higher than that of combined, 62.94%, by single EDTA. For PHE, the removal is 68.30%, 85.40%, 84.95%, respectively, which is 16.14%, 33.24%, 32. 79% higher than that of combined PHE, 52.16%, by single SDS. Thus, SDS washing followed by EDTA or mixture of SDS-EDTA washing concurrently is considered as the optimal washing sequence for PHE and Cu2+ removal.

[Flushing of phenanthrene in sandy soils by triton X-100 and sodium dodecyl sulfate].

A comparison of column flushing for phenanthrene-contaminated sandy soils was made by using an anionic surfactant, sodium dodecyl sulfate (SDS), a nonionic surfactant, Triton X-100 (TX100), and their mixed surfactants (SDS-TX100). The tested concentrations of surfactants were 1000, 1750, 2500 and 3250 mg x L(-1) while the mass ratios of SDS to TX100 (S:T) in the mixed surfactants were 1:1, 1:2 and 1:4. It was shown that the elution curves (phenanthrene concentration in elutant versus porous volume number) by SDS were zigzag fluctuating rather than regular patterns while those by TX100 and SDS-TX100 were regular ones in which the phenanthrene concentrations in elutant increased, achieved maximum and then decreased with the porous volume numbers of eluting solutions. Moreover, the maximum phenanthrene concentrations increased and the total porous volume numbers decreased with surfactant concentration increasing. Given the surfactant and total porous volume number, the removal efficiencies of phenanthrene were positively related to surfactant concentrations. The removal efficiencies by TX100 and SDS-TX100 depended on concentration and ratio of surfactant and were much larger than those by SDS. Given 1000, 1750 and 2500 mg x L(-1) of the surfactant concentrations respectively, the removal efficiencies by TXl00 and SDS-TX100 were more than 95% but the total porous volume numbers by SDS-TX100 were less than those by TX100. Given 3250 mg x L(-1) of the surfactant concentration, the total removal efficiencies by five surfactants (i.e., SDS, TX100, S:T = 1:1, S:T = 1:2 and S:T = 1:4) achieved their maximum values as 70.8%, 99.9%, 99.9%, 98.7% and 99.2%, respectively, but the needed porous volume numbers by TX100 were the least among those by all surfactants. The results illustrates that the factors such as type, concentration and ratio of surfactant play important roles in surfactant-enhanced flushing remediation for soils contaminated by organics.

[Washing copper (II)-contaminated soil using surfactant solutions].

The batch equilibrium washing of copper (II) in the soil matrix by anionic surfactant, sodium dodecylbenzyl sulfonate (SDBS), nonionic surfactant, octylphenoxypolyethoxyethanol (TX100), and their mixture (SDBS-TX100), was studied and compared. The influences of surfactant concentrations, washing time, pH values of solutions, ratios of soil to water and inorganic salts on washing efficiency were investigated. It was shown that the washing efficiency differed with the kinds of surfactants. Given the initial surfactant concentrations, the washing of copper (II) by single SDBS was greater than those by single TX100 and the mixed SDBS-TX100. The washing efficiency by 6 000 mg x L(-1) of SDBS was up to 46.3%, which was 5.8, 10.8, 10.8 and 19.3 times as those by SDBS-TX100 (3:1), SDBS-TX100 (1:1), SDBS-TX100 (1:3) and single TX100 respectively. When the ratio of soil to water was 1 to 10 and washing time reached 24 h, the washing efficiency achieved the maximum. pH values of solutions had obvious effect on the washing of copper (II). The washing efficiency of copper decreased sharply with the increase of pH. At the high acidity (pH = 1.50), the washing efficiency of copper (II) was up to 95%. The smaller the ratios of soil to water were, the higher the washing efficiencies would be. The existence of inorganic salts with the certain concentrations, such as Na+, Ca2+ and Mg2+, could not influence the washing capacity of surfactants, but the excessive Mg2+ (more than 500 mg x L(-1)) could resulted in the precipitation of SDBS. The results will make an implication for surfactant-enhanced remediation of soils contaminated with heavy metals.

Water solubility enhancements of PAHs by sodium castor oil sulfonate microemulsions.

Water solubility enhancements of naphthalene(Naph), phenantherene(Phen) and pyrene(Py) in sodium castor oil sulfonate(SCOS) microemulsions were evaluated. The apparent solubilities of PAHs are linearly proportional to the concentrations of SCOS microemulsion, and the enhancement extent by SCOS solutions is greater than that by ordinary surfactants on the basis of weight solubilization ratio(WSR). The logK(em) values of Naph, Phen, and Py are 3.13, 4.44 and 5.01 respectively, which are about the same as the logK(ow) values. At 5000 mg/L of SCOS concentration, the apparent solubilities are 8.80, 121, and 674 times as the intrinsic solubilities for Naph, Phen, and Py. The effects of inorganic ions and temperature on the solubilization of solutes are also investigated. The solubilization is improved with a moderate addition of Ca2+, Na+, NH4+ and the mixture of Na+, K+, Ca2+, Mg2+ and NH4+. WSR values are enhanced by 22.0% for Naph, 23.4% for Phen, and 24.6% for Py with temperature increasing by 5 degrees C. The results indicated that SCOS microemulsions improve the performance of the surfactant-enhanced remediation (SER) of soil, by increasing solubilities of organic pollutants and reducing the level of surfactant pollution and remediation expenses.