高分子附聚剂增大聚丁二烯胶乳粒径的研究

用丙烯酸正丁酯(BA)和甲基丙烯酸(MAA)合成了高分子附聚剂,并制备了大粒径聚丁二烯胶乳(PBL)。研究了PBL含量(在规定条件下烘干后剩余部分占总量的质量分数)、附聚剂用量和附聚剂中MAA含量对附聚效果的影响。结果表明:当PBL质量分数为30.0%、附聚剂质量分数为2.5%~3.0%、附聚剂中MAA质量分数为15.0%时,可制得粒径大于300 nm、粒径分布为单峰的稳定PBL。

Separation of baicalin from Scutellaria Baicalensis Georgi with polyamide

Separation of baicalin from Scutellaria Baicalensis Georgi with polyamide was studied. The adsorption isotherm, kinetic equation and desorption law were investigated by static and dynamic adsorption methods. The results show that the kinetic behavior is mainly controlled by the liquid film diffusion process and obeys the Boyd film diffusion equation. Equilibrium data for the adsorption of baicalin are correlated with Freundlich isotherm equation, i.e. q=3.8ce2.057, suggesting that the relative capacity of polyamide to baicalin is somewhat small. The desorption results indicate that the baicalin with mass fraction of 33.86% and the least impurities can be obtained by chromatography using 60% ethanol as the eluant at room temperature.

Sorption of Pyruvic Acid with Weakly Basic Polymer Sorbents

Uptakes of pyruvic acid for two types of commercially available weakly basic polymer sorbents, D301G and D301R, have been measured over a wide pH range and at various salinities of MgSO4. The results show that the overloading adsorption of pyruvic acid occurs on both weakly basic polymer sorbents, and the overloading models can predict the experimental data of uptake very well. The overloading value for D301G is larger than that for D301R. The adsorption isotherm of pyruvic acid for both polymeric sorbents is greatly affected by the solution pH and MgSO4 concentration in the aqueous phase, and a high recovery efficiency of pyruvic acid from aqueous solution can be obtained at the solution pH around 2.

ADSORPTION BEHAVIORS OF Pt(IV) AND Pd(II) ON POLYMERIC ESTER THIOUREA RESIN

Polymeric ester thiourea resin (PDTU-I) is a new kind of chelating resin with functional atoms S, N and O, so it is an excellent adsorbent for noble metal ions. In batch testes, the adsorption capacities of PDTU-I for Pt(IV) and Pd(II) increase with the increase of contact time, temperature and initial concentration of metal ions. The adsorption data fit Boyd's diffusion equation of liquid film, Langmuir adsorption isotherm and Freundlich adsorption isotherm. The maximum adsorption capacities calculated by Langmuir equation are 2.54mmol/g for Pt(IV) and 4.88mmol/g for Pd(II). According to FTIR and XPS results, functional groups of PDTU-I coordinate with noble metal ions in the adsorption process.

PREPARATION OF SURFACE ION-IMPRINTED ATTAPULGITE-SUPPORTED POLYMER AND ITS ADSORPTION BEHAVIORS OF Sr(II)

The surface ion-imprinting concept and chitosan incorporated sol-gel process were applied to the preparation of a new attapulgite-supported organic-inorganic hybrid polymer for selective separation of Sr(II) from aqueous solution. The prepared polymer was characterized with SEM, IR and XRD. The results showed that as a sorbent, it had good configuration and binding sites. Its adsorption behaviors for Sr(II) was investigated by FAAS and ICP-AES. The effects on adsorption capacities, including pH, quiescent time, and adsorbent amount were discussed, and the adsorption isothermal curve was obtained. Then the Kd a parameter estimating relative adsorbability, was conducted to study the selectivity towards Sr(II) of the prepared polymer. Under the optimum conditions, the ion-imprinted polymer offered a fast kinetics for the adsorption of Sr(II) and the maximum capacity was 12.9mg/g. The Kd and K parameters estimating relative adsorbability towards target ion, suggested that selective recognition of the ion-imprinted polymer towards Sr(II) was much higher than that of the non-imprinted polymer and attapulgite. Furthermore, the ion-imprinted polymer is of great regeneration capacity. The prepared functional polymer was shown to be promising for selective preseparation and enrichment of trace Sr(II) in environmental samples.

A NEW MODEL FOR ESTIMATION OF DIFFUSION COEFFICIENT OF PHENOL DESORPTION WITHIN POLYMERIC RESIN UNDER ULTRASOUND

A new model, phase equilibrium-kinetics model (PEKM), for estimation of diffusion coefficient was proposed in this paper. Kinetic experiments of phenol desorption on NKAII resin in the presence and the absence of ultrasound were separately conducted, and diffusion coefficients of phenol within an adsorbent particle were estimated by means of proposed PEKM and classic simplified model. Results show that the use of ultrasound not only changes the phase equilibrium state of NKA II resin/phenol/water system which had been equilibrium at normal condition, but also enhances diffusion of phenol within the resin. The diffusion coefficient of phenol in the resin in the field of ultrasound increases in an order of magnitude in comparison with the diffusion coefficient determined under no ultrasound. Experimental results also indicated that the diffusion coefficients estimated by PEKM were more accurate than that estimated by the classic simplified model.

PREPARATION OF UREA NITROGEN ADSORBENT OF COMPLEX TYPE AND ADSORPTION CAPACITY OF UREA NITROGEN ONTO THE ADSORBENT

The urea nitrogen adsorbent of complex type, which consists of chitosan coated dialdehyde cellulose （CDAC） and immobilized urease in gelatin membrane （IE）, was prepared. The cellulose, the dialdehyde cellulose （DAC） and the CDAC were characterized by scanning electronic microscope. The results indicate that the cellulose C2-C3 bond was broken under the oxidation of periodate and it was oxidated to DAC. The DAC was coated with chitosan and the CDAC was obtained. The adsorption of urea nitrogen onto the adsorbent in Na2HPO4-NaH2PO4 buffer solution was studied in batch system. The effects of the experiment parameters, including degree of oxidation of CDAC, initial urea nitrogen concentration, pH and temperature, on the adsorption capacity of urea nitrogen onto the adsorbent at CDAC/IE weight ratio 10：1 were investigated. The results indicate that these parameters affected significantly the adsorption capacity. The adsorption capacity of urea nitrogen onto the adsorbent was 36.7 mg/g at the degree of oxidation of CDAC 88%, initial urea nitrogen concentration 600 mg/L, pH 7.4 and temperature 37℃.

城市建设与土地问题

随着社会主义建设的发展及迅速城市化的过程,如何合理地利用城市建设土地的问题就自然地被提了出来。根据预测,苏联城市人口,到2000年将达到国家总人口的80%;事实上,苏联相当一部分城市将重建。每年新建、扩建的城镇需要占用土地6万到10万公顷,这类土地的30～45%为农庄和国营农场农业耕地。