Preparation of Cationic Starch by Electromagnetic Dry Process (EMDP)

Introduction Cationic starches are a series of products of which various sorts with different properties and usages can all be produced via cationic reactions by using different types of etherification agents under different conditions. As an additive and strengthening agent,

Efficient removal of algae and turbidity from water by a composite coagulant composed of a cationic starch and attapulgite

Algae and suspended colloidal particles produced high turbidity in water,weakened water purification,and threatened the safety of the water supply.In this study,a series of composite coagulants(atp-st-CTA)composed of a cationic starch(st-CTA)and attapulgite(ATP)with different fed mass ratios were fabricated by a simple method to coagulate kaolin suspension with initial turbidity of 80.0 NTU and Chlorella suspension with 0.25 mg/L of chlorophyll a(chla),respectively.Fourier transform infrared spectroscopy and scanning electron microscopy investigated the structural characteristics of atp-st-CTA.The maximum turbidity and chla removal rates of atp-st-CTA were 92.2%and 100.0%,respectively,at natural pH conditions.The effects of the fed mass ratio of st-CTA to ATP in the composites,dose,pH,and coexisting humic acid on the coagulation performance of atp-st-CTA were comprehensively investigated.Based on the apparent coagulation behaviors,the zeta potentials of the supernatants after coagulation,and the flocs properties,the coagulation mechanisms of atp-st-CTA were discussed in detail.The complete charge neutralization due to st-CTA and the enhanced sedimentation by ATP synergistically removed turbidity and algae from the water efficiently.In short,atp-st-CTA as a talented material has a notable prospect in applications of water treatment owing to its advantages of environmental friendliness,low cost,and high efficiency.

Thixotropy of Aqueous Suspensions Containing Mg-AI Hydrotalcite-like Compound and Low-substituted Cationic Starch： Comparison between Oscillatory Shear and Thixotropic Loop Measurements

The rheological properties of aqueous suspensions consisting of positively charged aluminum magnesium hydrotalcite-like compound （HTlc） and low-substituted cationic starch （LCS） were investigated. Special emphasis was placed on the thixotropic phenomenon. Thixotropic behavior was investigated by two thixotropic methods： thixotropic loop and oscillatory shear measurements. LCS molecules could be adsorbed onto HTlc particles due to the hydrogen bonding between ether groups or hydroxyl groups of LCS and hydroxyl groups of HTlc. The elastic dynamic response of the HTlc/LCS suspension increased with increasing mass ratio （R） of HTlc and a three-dimensional network structure could be formed in the suspension with higher R value. The thixotropic type of the HTlc/LCS suspension transformed from negative to positive and then to complex thixotropy when R changed from 0 to 0.5. By comparing between the thixotropic results obtained by thixotropic loop and oscillatory shear measurements, it was validated that the thixotropic loop for the suspension showing complex thixotropy had a crossover point.

Effect of algal flocculation on dissolved organic matters using cationic starch modified soils

Modified soils（MSs） are being increasingly used as geo-engineering materials for the sedimentation removal of cyanobacterial blooms. Cationic starch（CS） has been tested as an effective soil modifier, but little is known about its potential impacts on the treated water.This study investigated dissolved organic matters in the bloom water after algal removal using cationic starch modified soils（CS-MSs）. Results showed that the dissolved organic carbon（DOC） could be decreased by CS-MS flocculation and the use of higher charge density CS yielded a greater DOC reduction. When CS with the charge density of 0.052, 0.102 and0.293 meq/g were used, DOC was decreased from 3.4 to 3.0, 2.3 and 1.7 mg/L, respectively.The excitation–emission matrix fluorescence spectroscopy and UV254 analysis indicated that CS-MS exhibits an ability to remove some soluble organics, which contributed to the DOC reduction. However, the use of low charge density CS posed a potential risk of DOC increase due to the high CS loading for effective algal removal. When CS with the charge density of 0.044 meq/g was used, DOC was increased from 3.4 to 3.9 mg/L. This study suggested, when CS-MS is used for cyanobacterial bloom removal, the content of dissolved organic matters in the treated water can be controlled by optimizing the charge density of CS. For the settled organic matters, other measures（e.g., capping treatments using oxygen loaded materials） should be jointly applied after algal flocculation.

Influence of Inorganic Salts on the Adsorption of Cationically Modified Starch to Fibers

The article is focused on the influence of inorganic salts on the adsorption of cationically modified starch to fibers. Results show that low concentrations of inorganic salts usually affect the process of adsorption in a positive way. Adsorption efficiency at higher concentrations, however, depends on the type of inorganic salts as well as the sequence of adding inorganic salts and starch to paper suspension.

Heterogeneous Reactions between Starch and AKD under Solvent-free Conditions

Oxidized starch powder and cationic starch solution were reacted with alkyl ketene dimer(AKD) under heterogeneous conditions at 70℃ for 12 h.The AKD molecules reacted with starch hydroxyl groups to form β-keto ester linkages under the above conditions.The reaction products were separated into CHCl_3-soluble and CHCl_3-insoluble fractions.FT-IR spectroscopy,SEM,Xray diffraction,and TG-DTA analyses of the CHCl_3-insoluble fraction indicated that β-keto ester substituents were introduced to hydroxyl groups on the starch surfaces.The results indicated that hydrogen bonds between the starch molecules were disrupted under heterogeneous conditions upon heating.The activity and accessibility of hydroxyl groups were enhanced,as a result of which β-keto ester bonds were produced between AKD and starch.Based on these results,we speculate that the β-keto esters which existed in the sheets sized by AKD emulsions were generated by the reaction between AKD and starch.

Tailoring starch-engineered mineral particles towards enhanced interaction with cellulosic fibers

Interaction of unmodified starch with guest molecules or ligands(e.g.,fatty acids)as a basis for the formation of starch-encapsulated mineral filler particles is an effective process for mitigating the negative impact of filler addition on the strength properties of cellulosic networks.As unmodified starch is essentially nonionic,the interaction of starch-engineered fillers with negatively charged cellulosic fibers is somehow limited.Here,the concept of substituting unmodified starch with a minor amount of cationic starch in filler engineering with starch inclusion complexes was proposed.It was hypothesized that filler-fiber interaction would be enhanced by cationic-anionic attraction.Encouragingly,the effectiveness of this concept was demonstrated to be very pronounced.For instance,at a cationic starch percentage of 3%(relevant to the weight of total starch),filler retention and filler bondability with cellulosic fibers were significantly improved,leading to further mitigated negative impact of filler addition on tensile strength.Basically,this easily scalable concept may shed light on greener,more efficient use of filler technologies on the basis of starch inclusion complex formation,opening up new possibilities for real commercial applications.