Papers by Keyword: Phosphate

Abstract: To infer the early evolution of mollusc shell microstructures we must know the most ancient fossil record of molluscs. Fortunately the shells of many early molluscs are preserved via internal coatings and replacements by apatite that record sub-micrometer structural details that otherwise would be lost during diagenetic recrystallization. We herein discuss the methodology by which one can infer original shell microstructure from phosphatized fossils, pointing out the main problems and solutions in interpreting these traces of original shell crystal morphology. We also review the information these fossils have provided about the earliest evolution of the mollusc shell. Our long-term goal is to create a dataset of microstructures in early molluscs, which will be useful in understanding the incipient evolutionary arms race between molluscs and their predators, and will help elucidate how the mollusc biomineralization toolkit was built through time.

Abstract: Layered double hydroxide (LDH) is a compound and has exchangeable anion intercalated in its interlayer. LDH has been investigated to apply its interlayer anion as a useful material. We have been focused on interlayer phosphate. Phosphorus is an essential element for crop plants and an exhaustive resource. In this study, we investigated the phosphate elution from Mg/Fe LDHs and controlled its amount from two points of view. Firstly, we synthesized precursor of Cl^– intercalated Mg/Fe LDH by coprecipitation using NaOH solution. Next, the yielded precipitate was aged by two methods: reflux and hydrothermal treatments. Finally, HPO₄^2– adsorbed Mg/Fe LDH was synthesized by means of anion exchange of Cl^– with HPO₄^2– in Mg/Fe LDH. In XRD and EXAFS measurements, α-Fe₂O₃ was detected in the hydrothermal samples. The elution of phosphate was observed in Na₂CO₃ aqueous solution. After 24 hours, the eluted ratio of phosphate was 67% for the reflux sample and 23% for the hydrothermal sample. The decomposition was suppressed in the latter.

Abstract: The bamboo processing residues, as raw material, was modified by quaternary ammonium to obtain a quaternary ammonium modified bamboo powder adsorbent. The phosphate’s adsorption capacity of the powder adsorbent was investigated. In addition, the effects of dosage, pH, time, temperature, initial concentration on phosphate’s adsorption capacity. Then, the research performed the adsorption isotherm model fitting. The results showed that the adsorption rate of modified bamboo powder to phosphate increased with increase of dosing amount of modified bamboo powder, tended to be equilibrium when the removal rate reached to 97%; while the phosphate with high initial concentration could improve the adsorption capacity of modified bamboo powder. In acidic condition, the modified bamboo powder presented unsatisfied adsorption effect on phosphate, when pH= 6 the adsorption effect become well, but adsorption effect did not vary apparently with the increase of pH. With the increase of temperature (25, 35, 45°C), the maximum saturated adsorption capacity of modified bamboo powder gradually reduced. The adsorption of modified bamboo powder on phosphate was a rapid process, which could reach equilibrium status within 50 minutes. The bamboo powder before and after the modification was conducted IR element analysis, the values before modification are N=0, C=45.54 and H=6.03; while after the modification, the values are N=2.65, C=40.33 and H=6.79, it is concluded that the nitrogen content of modified bamboo powder increase obviously and the quaternary ammonium can well be grafted.

Abstract: Algeria has a fragile ecosystem, characterized by a relative scarcity of water resources and their preservation is a vital imperative. The excessive intake in the natural environment of nitrogen and phosphate load in wastewater, from agricultural activities, domestic and industrial pollution, represents a pollution threat and a serious danger to the aquatic environment. Municipal wastewater contains various wastes, and usually consists of about 99.94% liquid and 0.06% solids. If this wastewater is not treated or improperly collected, it can affect both public health and environment. In our study, we will focus on the biological treatment by natural lagoon and activated sludge, which suits perfectly our country, where space and climate are favorable factors; our main objective is to eliminate the maximum existing phosphorus in wastewater by these biological treatments, which can actually eliminate total phosphorus. Through these modes of treatment we try to remove the maximum of organic matter and phosphorus in the wastewater. Consequently, the receiving environment is preserved.

Abstract: The chemical quality of several water samples comprised groundwater from various aquifers and water dam, in Biskra area of South Algeria was investigated. Water samples were collected to monitor water chemistry of major ions and minor ions comprising inorganic pollutants such as fluoride, phosphates, nitrates and trace element as cadmium. The results showed a high salinity associated with an excessive hardness. The concentrations of many inorganic compounds are above the permissible limits for standard drinking water in almost water sources. The pollution is mainly attributed to a geological origin and an extensive use of fertilizers. Some water need adequate treatment to overcome inorganic pollution problem for drinking purpose. The adsorption of fluoride, nitrate, phosphate and cadmium ions onto Algerian bentonitic clay was studied in batch system. The results showed that sulphuric acid activated bentonite was more efficient than raw clay for fluoride, nitrate and phosphate removal. The results also revealed that cadmium adsorption was better with raw bentonite. The equilibrium data were confirmed using Langmuir isotherm model.

Abstract: Mg and its alloys draw more and more attentions to be used as biodegradable medical materials. But the rapid degradation of those materials limits their clinical applications. In this article, a phosphate coating was prepared on AZ31B magnesium alloy to improve its anti-corrosion property. Morphology, composition and corrosion resistance of the coating were studied. The SEM research showed that the coating that composed of rod-like phosphates with small amount of random distributed micro-voids was approximately10-20μm in thickness. The XRD analysis indicated that the coating was mainly composed of MgO, Mg₃(PO₄)₂and Zn₃(PO₄)₂·xH₂O. Electrochemical test showed the phosphate treatment could significant improve the corrosion resistance of AZ31B.

Abstract: Lead pollution, commonly found in lead-acid battery plants or electroplating manufactures, has drawn more and more attention due to its intrinsic toxicity to human health and potential disturbances to local ecological system. Soluble phosphates showed great advantages over other inorganic stabilizers and could provide a rapid, cost-effective approach for lead contaminated sites, despite of complex contaminants presence and heterogeneity distribution of contamination. Chemical stabilization using soluble phosphates was demonstrated by immobilize both lab samples and on-site samples from a local lead contaminated site in this study. The soil samples were mixed with soluble phosphates and stabilized for selected intervals, while adding supplements for the purpose of pH control and solidification. Experiments for treatment duration and immobilization rate in comparison with other stabilizers were also investigated to provide guidance for following demonstration project. Soil samples were analyzed before and after the treatments to compare lead immobilization rates under different circumstances. The results suggested that 90% of lead in lab soil samples was stabilized after one day treatment with phosphates, while on-site soil samples took another 30 to 50 days due to their complexity. Phosphates treatment showed great consistence over all the soil samples after 50 days in contrast with the performance of lime treatment and ferrous sulfate stabilization. It is recommended that the stabilization duration for the specific site should be longer than 30 days, at an average cost of stabilization per ton of soil around 300 RMB. This study demonstrated the use of soluble phosphates in pilot-scale lead pollution remediation, as well as the possibility of extending the remediation concept for other heavy metal contamination scenarios. In addition, chemical stabilization could also be combined with other remediation technology in future due to its simplicity and convenience.

Abstract: This article uses hydroxylethyl acrylate and phosphorylation reagent for esterification reaction, synthesis of a phosphate ester monomer with double bonds, and phosphate ester monomer ,Participation as the third monomer polymerization of acrylic acid and isoprene polyoxyethylene ether (TPEG). Polycarboxylate was synthesized with phosphoric acid ester structure,Investigate the impact of Phosphate ester content in single and double to polycarboxylate performance. The results showed that the polycarboxylate with phosphate structure has excellent adaptability and reduction of water slump performance.

Abstract: Industries producing fertilizers, aluminium, steel, bricks, glass, and semiconductor discharge several thousand tons of phosphate and fluoride per year into the open atmosphere in the form of wastewater which cause many environmental issues as well as loss of drinking water. The objective of this review is to select the suitable method for the removal of phosphate and fluoride from industrial wastewater which is highly hazardous and acidic in nature. So that treated water can be reused for agricultural and industrial purposes. Industries discharge several thousand tons of phosphate and fluoride per year in the form of wastewater which cause many environmental issues and loss of drinking water. This review is provided with aimed a precise and accurate knowledge for the removal of phosphate and fluoride from industrial wastewater. A lot of technologies are available for the treatment of industrial wastewater treatment including chemical precipitation, crystallization, ion exchange, adsorption, reverse osmosis and nanofiltration methods. The selection of most suitable treatment technology is based on retention time, principle of operation, applications, chemicals and maintenance cost.

Abstract: In view of the mid-low grade phosphate rock somewhere in Yunnan province, first of all study the mechanical properties of ore, on the basis of which combine Duanshi semi diameter theory formula and crushing statistic mechanics, optimized from diameters, shapes and proportion of the grinding medias, increasing the grinding selectivity only to get selective optimization scheme, finally proved by practice, after changing the media system, on the basis of original mill processing capacity increased by 19.54%, the average steel consumption reduced more than 10%, the particle size of grinding product is easy to process, having an obvious energy saving effect.