An investigation into the occurrence of sewage fungus in rivers containing papermill effluents—I. Review of previous research

Wastewaters from the manufacture of pulp and paper have given rise to problems of excessive microbial growth in rivers over a number of years. This paper is the first in a series of four articles describing research undertaken by PIRA at four U.K. paper/board mills (one integrated with pulp production) over the period 1978–1980. This first paper briefly reviews the published literature on sewage fungus growth from pulp and paper mill discharges up to 1978, but mainly describes previously unpublished work undertaken by PIRA over the period 1965–1975. This introductory paper thus provides a state-of-the-art review of methods to control sewage fungus growth from pulp and paper mill effluents prior to commencement of the research described in the following three articles.     

The Effects of Different Plasticizers on the Properties of Thermoplastic Starch as Solid Polymer Electrolytes

Plasticizers with amide groups (urea and formamide) and polyols (glycerol, glucose, and sorbitol) were used to prepare thermoplastic starch (TPS) containing NaCl salt as solid polymer electrolytes (SPE). Fourier Transform infrared (FT‐IR) spectroscopy revealed that both plasticizers and Na⁺ could form the interaction with starch, and plasticizers containing amide groups had stronger hydrogen bond‐forming abilities with starch than polyols. These interactions prevented starch molecules from crystallizing again, indicated by X‐ray diffraction (XRD). Scanning electron microscope (SEM) showed that starch granules were in a molten state and a continuous phase of TPS was formed. Among TPS as SPE, formamide‐plasticized TPS (FPTPS) had the largest elongation at break and lowest tensile stress. The conductance of TPS was sensitive to water. TPS plasticized by solid plasticizers had the higher sensitivity of the conductance to water contents at the low water contents (<0.1). The relationship of the conductance and water contents was in agreement with the second‐order polynomial correlation when water contents were below 0.45. FPTPS had the best conductance as a whole. At the medium water content (0.2), the conductance of FPTPS containing NaCl was about 10^?3 S · cm^?1.

     

复杂硫化矿中铜的综合回收新工艺试验研究

七宝山铁矿铅锌矿区伴生一定储量的具有综合回收价值的铜矿物。根据矿物特性 ,吸取以往我矿铜回收的技术经验 ,采用优先浮铜的工艺流程 ,利用ZM作捕收剂 ,淀粉作铅矿物的抑制剂 ,有效地解决了铜、铅矿物分离的问题 ,取得了铜精矿品位 2 1.48%、回收率为 5 9.3 8%、含铅 7.90 %、含锌 7.3 3 %的良好试验指标。本试验研究工业应用前景广阔。     

Development and Physicochemical Characterization of New Resistant Citrate Starch from Different Corn Starches

Resistant starch has drawn broad interest for both potential health benefits and functional properties. In this study, a technology was developed to increase resistant starch content of corn starch using esterification with citric acid at elevated temperature. Waxy corn, normal corn and high‐amylose corn starches were used as model starches. Citric acid (40% of starch dry weight) was reacted with corn starch at different temperatures (120–150°C) for different reaction times (3–9 h). The effect of reaction conditions on resistant starch content in the citrate corn starch was investigated. When conducting the reaction at 140°C for 7 h, the highest resistant starch content was found in waxy corn citrate starch (87.5%) with the highest degree of substitution (DS, 0.16) of all starches. High‐amylose corn starch had 86.4% resistant starch content and 0.14 DS, and normal corn starch had 78.8% resistant starch and 0.12 DS. The physicochemical properties of these citrate starches were characterized using various analytical techniques. In the presence of excess water upon heating, citrate starch made from waxy corn starch had no peak in the DSC thermogram, and small peaks were found for normal corn starch (0.4 J/g) and Hylon VII starch (3.0 J/g) in the thermograms. This indicates that citrate substitution changes granule properties. There are no retrogradation peaks in the thermograms when starch was reheated after 2 weeks storage at 5°C. All the citrate starches showed no peaks in RVA pasting curves, indicating citrate substitution changes the pasting properties of corn starch as well. Moreover, citrate starch from waxy corn is more thermally stable than the other citrate starches.     

Lintnerization of Two Amylose‐free Starches of A‐ and B‐Crystalline Types,Respectively

Waxy maize starch (WMS) and potato amylopectin starch (PAPS), representing amylose‐free A‐ and B‐crystalline granules, respectively, were subjected to hydrolysis in diluted hydrochloric acid (lintnerization). The solubilization rate of the granules was dependent on the temperature, but there were only small differences between the samples. The compositions of the lintners obtained at 29°C were also similar, though the sensitivity to enzymatic debranching was different. The degree of debranching increased significantly if pullulanase and isoamylase were used successively. Because some branches remained resistant to enzymatic attack, the degree of scattered branching was difficult to estimate. The amount and composition of β‐limit dextrins suggested, however, that both starches contained scattered branches. Long chains and the shortest chains in the amylopectin molecules were sensitive to lintnerization and therefore probably located outside the crystallites. The composition of the PAPS lintners was dependent on the temperature of the lintnerization, whereas that of WMS lintners was not. The composition of a lintner from normal potato starch was compared with PAPS, and it is concluded that the presence of amylose has a higher effect than the type of crystallinity on the lintnerization results.     

Development of Hydrophobic Starch

The aim of this work was a systematic investigation of the preparation conditions for stable aqueous dispersions of hydrophobic starch. Samples of benzylated starch were therefore synthesised and then converted into hydrophobic dispersions by fragmentation. In the study, the type of starch and process parameters such as the degree of hydrophobic substitution and fragmentation method were varied. It was shown that the type of derivatisation process (i.e. heterogeneous in a slurry or homogeneous in an autoclave) had a crucial influence on the dispersion properties. Dilution from homogeneous solution and steam‐jet cooking were explored as fragmentation methods for the starch derivatives. The resulting dispersions were comprehensively characterised in relation to the molecular properties of the soluble fraction and sediment. Significant differences in dispersion properties were caused by the type of starch used (i.e. potato or maize) and the derivatisation process, for a similar degree of benzylation.     

EPR Studies of Thermally Treated Oxidized Corn Starch

The formation of radicals in oxidized corn starch at 20–250°C in air was investigated by quantitative EPR spectroscopy. It was found that the presence of carboxyl groups in the oxidized starch increases the starch's ability to generate radical species. Introducing Cu²⁺ ions into the starch, as a catalyst or as an EPR probe, leads to the formation of copper‐carboxyl complexes containing two carboxyl ligands. Drastic increase in the number of radical species at about 250°C is accompanied by a decrease in the intensity of EPR signal of Cu²⁺‐carboxyl complexes, indicating that the thermal degradation of oxidized corn starch occurs with the formation of radicals, probably via breaking the chemical bonds in the carboxyl groups.     

In vitro Digestibility of Cross‐Linked Starches – RS4

In vitro digestibility of cross‐linked starches (RS4 type), which were prepared from wheat, corn, rice, potato, and high‐amylose corn starches, was determined by Prosky AOAC and pancreatin gravimetric (P/G) methods. The RS levels of RS4 starches obtained by the AOAC method were higher than those by the P/G method. Pronase treatment before digestion with heat‐stable α‐amylase (AOAC method) gave similar RS levels as those by P/G method. The shapes of residues after digestion by the AOAC method were not different from untreated ones, but those after digestion by the P/G method showed irregular and fluffy forms. It was found that the P/G method provided more exhaustive digestion of RS4 starches than the AOAC method.     

季铵型阳离子淀粉合成及应用

介绍了季铵型阳离子淀粉的湿法生产工艺,着重讨论了合成反应过程中催化剂用量、醚化剂用量、反应温度、反应时间等因素对取代度和反应效率的影响。淀粉用量为100kg,醚化剂CHPT用量为5,2kg,催化剂用量为2．6kg,淀粉乳浓度58％,氢氧化钠水溶液浓度50％、反应温度50℃、反应时间15h。在此条件下,取代度可达0．0268,反应效率达80％以上。     

国内近期包装用淀粉粘合剂研究概况

介绍了包装用淀粉粘合剂的种类,配方,作有原理及国内研究现状。