Effect of Competitive Adsorption between Sodium Tripolyphosphate and Naphthalene Superplasticizer on Fluidity of Cement Paste

The adsorption amount, ξ-potential of cement particles and fluidity of cement paste were tested to research the competitive adsorption between naphthalene superplasticizer （FDN） and STPP. The experimental results showed that the presence of STPP could significantly improve the fluidity of cement paste and reduce the fluidity loss with FDN. There existed a competitive adsorption between STPP and FDN. STPP and calcium ions formed complexes; they preferentially adsorbed onto surface of cement particles and preempt adsorption points of FDN; and it reduced adsorption amount of FDN. In the absence of STPP, saturation adsorption amount of FDN was 5.93 mg/g; but when the dosage of STPP was 0.1%, it reduced to 4.3 mg/g （about 72.5%）. The adsorption amount of FDN was reduced by STPP, but ξ-potential of cement particles enhanced and fluidity of cement paste increased because of strong negative charge effect of the complexes. Adsorption of the complexes would delay Ca^2＋ into liquid and inhibit formation of active adsorption points. Then, content of FDN in liquid increased with the addition of STPP and ξ-potential of cement particles became stable. In this way, fluidity loss of cement paste reduced.

Effect of Compounding of Sodium Tripolyphosphate and Super Plasticizers on the Hydration of α-calcium Sulfate Hemihydrate

The inhibition and its mechanism of sodium tripolyphosphate （STP） composited with super plasticizers （SPs） on hydration of α-calcium sulfate hemihydrate were studied by setting time, strength, hydration heat, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, electronic probe micro analysis （EPMA）, scanning electron microscopy （SEM） and differential scanning calorimeter （DSC） measurements. The experimental results show that compared with STP addition, compositing STP with polycarboxylate （PC） plasticizer, the final setting time is prolonged from 0.5h to 2hs. While formulating STP with naphthalene-based plasticizer （NAP） or sulfonate melamine formaldehyde plasticizer （SMF）, the final setting time is reduced to quarter of an hour. Similar changes can also be found in the rate of exothermic hydration and hydration degree. Formulating STP with suitable addition of PC can enhance the strength, while compositing STP and NAP or SMF weakens the strength. Besides, adding STP or STP and SMF, obvious movement （more than 1ev） of binding energy of Ca2p1/2 and Ca2p3/2 is detected. Compared with STP addition, content of the characteristic element （P） of STP is cut down form 1.1% to 0.49% by compositing STP with SMF. Furthermore, as hydration age increases, hydration inhibition in the presence of admixtures weakens and even disappears within 56 h.

Oxidative degradation of phenol by sulfidated zero valent iron under aerobic conditions:The effect of oxalate and tripolyphosphate ligands

After adding either organic or inorganic ligands,sulfidated nano-zero-valent iron(Sn ZVI)was used for aerobic degradation of phenol,and the effect of the ligand species on oxidation performance was investigated.We found that Sn ZVI hardly degraded phenol in the absence of ligand addition.Ligands initiated and promoted the degradation of pollutants by Sn ZVI.The data herein show that a characteristic inorganic ligand,tripolyphosphate(TPP),is more effective in enhancing oxidation than a characteristic organic ligand oxalate.In addition to the scavenging of reactive oxidants by the organic ligand,more ferrous ion(Fe(Ⅱ))dissolution from Sn ZVI in the TPP system is another cause for the superior enhancement by the inorganic ligand.In the oxalate system,as the sulfur content of Sn ZVI increased,the oxidation efficiency increased because Fe S shell promoted the transfer of electrons to produce more reactive oxygen species(ROS).In TPP system,the effect of sulfur content on oxidation performance is more complex.The Sn ZVI with low sulfur content showed poor oxidation performance compared with that of n ZVI.Further experiments proved that sulfidation might weaken the complexation of TPP with surface bound Fe,which would slow down the ionic Fe(II)dissolution rate.Therefore,sulfidation has the dual effects of enhancing electron transfer and inhibiting the complexation of inorganic ligands.In addition,the mechanisms of ROS generation in different ligand systems were investigated herein.Results showed that the critical ROS in both the oxalate and TPP systems are hydroxyl radicals,and that they are produced via one-electron activation of O_(2).

Degradation of organic contaminants through the activation of oxygen using zero valent copper coupled with sodium tripolyphosphate under neutral conditions

In this study,sodium tripolyphosphate(STPP)was used to promote the removal of organic pollutants in a zero-valent copper(ZVC)/O2 system under neutral conditions for the first time.20 mg/L p-nitrophenol(PNP)can be completely decomposed within 120 min in the ZVC/O2/STPP system.The PNP degradation process followed pseudo-first-order kinetics and the degradation rate of PNP gradually increased upon the decreasing ZVC particle size.The optimal pH of the reaction system was 5.0.Our mechanism investigation showed that Cu+generated by ZVC corrosion was the main reducing agent for the activation of 02 to produce ROS.-OH was identified as the only ROS formed during the degradation of PNP and its production pathway was the double-electron activation of O2(O2→H2 O2→·OH).In this process,STPP did not only promote the release of Cu+through its complexation,but also promoted the production of OH by reducing the redox potential of Cu2+/Cu+.In addition,we could initiate and terminate the reaction by controlling the pH.At pH<8.1,ZVC/02/STPP could continuously degrade organic pollutants;at pH>8.1,the reaction was terminated.STPP was recycled to continuously promote the corrosion of ZVC and O2 activation as long as the pH was<8.1.This study provided a new and efficient way for O2 activation and organic contaminants removal.

Synthesis and Characterization of Phosphated Konjac Glucomannan Hydrogels

Konjac glucomannan （KGM） was crosslinked with sodium tripolyphosphate （STPP） to synthesize hydrogels. The crosslinking reaction was confirmed by FT-IR. The results of degradation test show that the hydrogels retain the enzymatic degradation character of KGM and can be degraded for 74.45% in 5 days by cellulase E0240.

Effect of counter-ion agents on metronidazole loaded chitosan microparticles prepared by w/o emulsification method

Chitosan microparticles for controlling drug delivery have been prepared by water in oil(w/o)emulsification process.Glutaraldehyde is normally used as cross-linking agent for hardening chitosan polymer into the rigid particles[1].From the cationic charge of ammonium groups in chitosan structure,moreover,it is also possible to cross-link the polymeric chain by the anionic counter-ion substances.Sodium hydroxide(NaOH)and tripolyphosphate(TPP)are the rich negatively charged molecules that are normally used in pharmaceutical preparations.They might be more appropriate to be chosen for the co-crosslinking process due to its safety[2].Therefore,this study aimed to investigate the effect of counter-ion NaOH and TPP agents on the properties of chitosan microparticles crosslinked by glutaraldehyde.Metronidazole was used as model drug loaded in these systems.

The Role of Flotation Reagents in the Reverse Flotation of Carbonate-Containing Iron Ores

The Influence of pulp pH, dispersants and auxiliary collectors on reverse flotation of carbonate-containing iron ores were explored. Interactions between iron ores and quartz were theoretically analyzed by flotation solution chemistry and DLVO theory. The results indicated that the iron concentrate grade improved sharply when pH increased from 11.0 to 12.0, but changed unobviously when pH was larger than 12.0, which was related to solution chemistry of siderite and interactions among particles. Sodium tripolyphosphate was an effective dispersant and sodium dodecyl sulfate was an effective auxiliary collector of KS-III. Both recovery and grade enhanced by the action of sodium dodecyl sulfate or sodium tripolyphosphate when pH was 12.0.

Preparation of chitosan–TPP nanoparticles and their physical and biological properties

Over the last few decades,several polymeric nanoparticles using biomaterials have been extensively developed for use as drug delivery systems(DDS)and for other medical applications.Therapeutic nanoparticles have the advantage of controlled drug-targeting delivery and release,which improves the stability,enhances the efficiency and reduces the side effects of the drug[1].Chitosan is a versatile polymer that has been used in drug delivery system as nanoparticles because of biodegradable,biocompatible,and low toxicity[2].

Mathematical model for the ubiquitin activating enzyme E1

The ubiquitin-activating enzyme E1 (EC 6.3.2.19) represents the first step in the degradation of proteins by the ubiquitin proteasome pathway. E1 transfers ubiquitin from the ubiquitinated E1 to the ubiquitin carrier proteins (E2), ubiquitin-protein ligases (E3) and proteins. This process is rather complex, and known from the work of Haas, Ciechanover, Hershko, Rose and others. The occurrence of 19 hypothetical intermediate enzyme forms (EFs) and 22 different reactions were considered in the presence of ubiquitin (Ub), ATP, adenosine 5’-tetraphosphate (p4A), pyrophosphate (P2), and tripolyphosphate (P3) as substrates, and iodoacetamide (IAA) and dithioth- reitol (DTT) as inhibitors. Inspired by the work of Cha (Cha (1968) J. Biol. Chem., 243, 820-825) we have treated these reactions in two complementary ways: in rapid equilibrium and in steady state. The kinetics of both types of reactions were simulated and solved with a system of ordinary differential equations using the Mathematica Program. The ubiquitination of E1 has been also theoretically coupled to the ubiquitination of E2, E3 and proteins. This makes the model useful to predict the theoretical influence of inhibitors (or of changes in some parameters of the reaction) on the ubiquitination of proteins. The Program responds to changes in the concentration of ATP or ubiquitin and has predictive properties as shown by the influence of AMP on the synthesis of p4A, calculated theoretically and confirmed experimentally.