[Comprehensive undergraduate experiment: synthesis and chromism of 4-[bis(4-methylphenyl)amino] benzaldehyde].

To solve the problems of the lack of property research in organic synthesis experiments and the relative independence of instrumental analytical methods in experiments, we designed a comprehensive undergraduate experiment based on mechanofluorochromic materials. In this project, 4-[bis(4-methylphenyl)amino] benzaldehyde was synthesized via the Vilsmeier-Haack reaction using 4,4'-dimethyltriphenylamine as the raw material. The product was then characterized by mass spectrometry, infrared absorption spectroscopy, and nuclear magnetic resonance spectroscopy. The solvatofluorochromism and mechanofluorochromism of the target material were studied using ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, etc. Furthermore, the mechanism of mechanofluorochromism was determined using powder X-ray diffraction. Organic synthesis and a series of instrumental analytical methods were combined to form an integrated experiment. The experiment is interesting, scientific, and comprehensive for undergraduates as a creative exercise; moreover, it can inspire their interest in chemical research, cultivate a variety of experimental operation abilities, improve creative-thinking skills, and encourage the development of effective solutions to existing problems in chemical experiments.

[Response of FTIR and Raman Spectra on Cell Wall of Calendula Officinalis Seedlings Roots to the Co-Contamination Stress of Lead and Cadmium in Loess].

Phytoremediation is a novel method with great potential for site remediation contaminated by heavy metals in future. The cell wall of plant roots is significant to affect the remediation efficiency, for it is related to the multi-interface of heavy metals, pedosphere and plant. The relationship between cell wall of plant and heavy metals is complicated, containing the reaction behavior of physical chemistry, physiology and biochemistry. At present, the spectral technologies are not adequately used to investigate the in-situ response characteristics between cell wall of plant roots and heavy metals. The Calendula officinalis seedlings, the remediation plant in loess, were used as experimental sampleswhile the root characteristic variation was revealed on cell wall. The approaches of X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Raman spectra were applied to analyze the response effect of cell wall to lead/cadmium stress. The results showed: the cell wall appears to be shrinking, and certain amounts of dark particles appear on cell wall. The contents of lead/cadmium increase greatly as shown from XRF, while the representative crystals of lead/cadmium are hardly detected. The absorbance peak at 3 416 cm-1 indicates the coordination effect between lead/cadmium and ­OH in FTIR, and the movement of absorbance peaks, from 1 701 to 1 736 cm-1 and 1 593 to 1 618 cm-1, respectively, indicates the different characteristics of protein in cell wall of Calendula officinalis seedlings roots under lead/cadmium stress. The Raman intensity of absorbance peak at 2 960 cm-1 increases under lead/cadmium stress, and it proves the changes on arranging directions of cellulose molecules in cell wall samples. The components (Pectin, protein, cellulose, etc.) and functional groups (­OH, N­H, CO, etc.) of cell wall play an important role in the resistance process of cell wall derived from Calendula officinalis seedlings roots to the stress of lead/cadmium in loess.

[Study on the Mechanism to Ease the Leaching Effect of Nutrient in the Multi-Contaminated Loess Washing Process with the Addition of Anion Adsorbent(â ¡)].

The soil washing technology is commonly used to remediate contaminated soils because of its advantages of low cost, ease handling and environmental-friendly. However, it should be noticed that the nutrient might leach simultaneously from soil in the washing process, and the technical solution of the issue will greatly accelerate the application process of washing technology in site remediation. This paper aims to reveal the regulating mechanism of synthesized anion adsorbent from straw on nutrient leaching potential through approaches of adsorption equilibrium models (isotherms and kinetics) and spectral analysis instruments (SEM and FTIR). The results showed: the Langmuir isotherm and pseudo second order kinetic equation fit better the adsorption behavior of nitrate and phosphate. The maximum adsorption capacity (qm), calculated with Langmuir isotherm, are 7.507 5 and 4.194 6 mg·g-1, respectively, and the reaction belongs to the monolayer and favorable adsorption with chemical adsorption the rate-determining step. The activation energy of adsorption for nitrate and phosphate at 298 K are 42.25 and 39.38 kJ·mol-1, respectively, and the reaction is spontaneous and endothermic. The purified water and KOH solution are effective for the regeneration of anion adsorbent, the desorption effect is better for the assistance of ultrasonic sound and longer desorption time. The surface of anion adsorbent after adsorption is covered with particles, while less spray-like component appears after desorption with purified water. The movement of vibration peaks in FTIR spectra indicates the effect of electrostatic interaction in the reaction. The adsorption of nitrate and phosphate on anion adsorbent involves simultaneously the effects of physical and chemical adsorption.

[FTIR Analysis of Secondary Abiotic Stress Response of Calendula Officinalis Seedlings to Lead and Cadmium in Multi-Contaminated Loess].

As an environmentally-friendly technology attracting great attention from current researchers, phytoremediation is significant for site remediation contaminated by heavy metals. The plant will appear related physiological response to reduce direct harm caused by the stress of heavy metals. The microscale behavior is always multi-dimensional and difficult to detect. The advanced instruments are effective to resolve the scientific issues, while the related researches are seldom investigated. Taking calendula officinalis seedlings as experimental samples, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) were applied to compare the surface characteristics and functional groups variation, respectively. The response process and tolerance mechanism of calendula officinalis seedlings to lead and cadmium stress were further analyzed. The results showed: with the increasing concentration of lead and cadmium in loess, the calyptra of calendula officinalis seedlings become bending and wilting; the amount of root hairs decreases greatly while no significant variations of aerial parts are found on surface characteristics. The stress of lead and cadmium are responsible for the difference of FTIR spectra of Calendula officinalis seedlings. The peak absorbance at 3 573 cm-1 decreases and the peak becomes more complex with the increasing contents of lead and cadmium. It might be the coordination effect between lead/cadmium and hydroxyl, which affects the synthesis and secretion of organic matters. The movement of C­H vibration peak is associated with the lipid oxidationwhile the changes at 1 631 and 1 574 cm-1 suggest the protein component differences. The shifting peak at 1 385 cm-1 might be associated with the methylation of pectin and lipid, and the behavior is positive for the adaption process of calendula officinalis seedlings to lead and cadmium stress. The FTIR spectra are effective to reveal the phytoremediation mechanism on heavy metals contamination in pedosphere.

[Determination of Lead and Cadmium in Calendula Officinalis Seedlings for Phytoremediation of Multi-Contaminated Loess by Using Flame Atomic Absorption Spectrometry with Wet Digestion].

Atomic absorption spectrometry (AAS) is widely used in the analysis and detection of heavy metals. The optimal operation conditions on metals detection are important for the stabilization and repeatability of scientific research, which affects the expected investigation objectives greatly. Thus, it becomes a key issue to establish appropriate detection methods in scientific works. Calendula officinalis was used for lead/cadmium remediation in contaminated loess, and the flame atomic absorption spectrometry (FAAS) with wet digestion was applied to analyze the contents of lead/cadmium in Calendula officinalis seedlings. The investigation data was further studied to reveal the bioaccumulation efficiency of lead/cadmium in Calendula officinalis seedlings. The results showed: the limits of detection are 0.104 and 0.007 mg·L-1 for lead and cadmium; the recovery rates of lead and cadmium are from 94.33% to 110.78% and 97.73% to 107.50% respectively. The relative standard deviations (RSD) are between 4.11% and 4.75% for lead while between 1.11% and 2.77% for cadmium，and It's been proved that the method is accurate and reliable. The low accumulation efficiency of lead with Calendula officinalis seedlings might be related to the electronegativity of lead while the growth period of calendula officinalis seedlings and environmental factors. The accumulation content of cadmium is 104.85 mg·kg-1 with cadmium concentration of 50 mg·kg-1. The co-existing of lead in loess is positive for cadmium accumulation by Calendula officinalis seedlings, and the synergistic effect might work in the process. The established detection method is effective for quantitative analysis of lead and cadmium in calendula officinalis seedlings and significant for future research.