?hydroponics

hydroponics發(fā)音

英：[?ha?dr??p?n?ks]　　美：[?ha?dr??pɑn?ks]

英：　　美：

hydroponics中文意思翻譯

n. (單復同)水耕法, 水栽培

hydroponics詞形變化

副詞: hydroponically | 名詞: hydroponicist | 形容詞: hydroponic |

hydroponics常見(jiàn)例句

1 、Hydroponics or soil-less culture is a technology for growing plants in nutrient solutions that supply all nutrient elements needed for optimum plant growth.───水培或無(wú)土栽培是一種用營(yíng)養液來(lái)栽培農作物的技術(shù)，營(yíng)養液可以提供農作物生長(cháng)所必需的所有營(yíng)養元素。

2 、In the research, 66 maize genotypes were studied by hydroponics experiments.───采用水培方法對66個(gè)玉米雜交種進(jìn)行氮脅迫下玉米適應性篩選研究。

3 、And finally it made the conclusion that the way of hydroponics would be widely used in medicinal plant study.───指出溶液培養法將在藥用植物研究中得以廣泛應用。

4 、The system, called Grow-Tech 2000, grows vegetables and other crops inside standard metal shipping containers using hydroponics,───被稱(chēng)作“種植技術(shù)2000”的系統是一種利用溶液培養學(xué)技術(shù)在一個(gè)標準的金屬集裝箱內生產(chǎn)蔬菜和其它農作物的種植系統。

5 、Computers control the collection and recycling of waste, which is injected into large vats of algae which consume the waste or processed into fertilizer for the Space Ship hydroponics garden.───在飛船中，必須由電腦控制，歸集并再利用這些廢棄物，把這些廢棄物注入到一個(gè)含有大量藻類(lèi)的分解槽之中，將它們制成肥料然后用在飛船上無(wú)土栽培的植物園之中。

6 、Keywords wastewater;purification;turtle-breeding;hydroponics;cos lettuce;───廢水;凈化;養鱉廢水;水培;生菜;

7 、Today this method of farming is called hydroponics.───現在把這種栽培方法叫做水栽法。

8 、hydroponics chlorophytum comosum───水培吊蘭

9 、Hydroponics (water culture) The growth of plants in liquid culture solutions rather than soil.───水培：是在液體培養基中栽培植物而不是在土壤中。

10 、Flower plant hydroponics───花卉水培

11 、Providing technical consultation on hydroponics vegetable production programme, forced culture facilities and related areas for 14 units both in and out Jiangsu province;───幫助省內外14個(gè)單位規劃設計蔬菜無(wú)土栽培生產(chǎn)基地與設施，并提供技術(shù)知道與咨詢(xún)服務(wù)；

12 、I learned a ton at boarding school ritual hazing, keg stands, advanced hydroponics.─── 我在寄宿學(xué)?？墒菍W(xué)到不少 欺負新人 倒立喝酒 種大麻

13 、Hydroponics was employed to study the effects of different nutritional levels on root vigor and free amino acid composition and content of Astragalus membranaceus seedlings.───摘要運用水培試驗法研究不同營(yíng)養水平對黃芪幼苗根系活力和游離氨基酸組成及含量的影響。

14 、We used to grow hydroponic pot out here.─── 我們以前在這里種水培花盆

15 、Abstract : This paper discussed the effect of budburst detached peach branch with different chemicals, different temperature and different grads by hydroponics.───摘要 ： 用水培的方法研究了不同的化學(xué)藥劑、不同的溫度、不同的水培梯度對桃樹(shù)離體休眠枝條萌芽開(kāi)花的影響。

16 、2、Hydroponics in Horticulture; Published by Academic publishing company in Korea; 1999.───親環(huán)境營(yíng)養液栽培；韓國全南大學(xué)出版社,1999。

17 、Study on the hydroponics technique of leaf vegetables with low-nitrate content───低硝酸鹽葉菜類(lèi)蔬菜水培技術(shù)研究

18 、They're using distilled water in the hydroponic supply instead of the proper mineral solutions needed for longterm stability.─── 他們在水培物質(zhì)里使用的是蒸餾水 而不是植物長(cháng)期穩定生長(cháng)所需的 合適礦物質(zhì)溶液

19 、Please show the brief differentia between hydroponics and soil culture.───請簡(jiǎn)要說(shuō)明營(yíng)養液栽培與土壤栽培在植物養分供應上的不同點(diǎn)。

20 、Effects of harvesting time and controlled supply of nitrogen on nitrate content of Brassia campestris in hydroponics───不同收獲時(shí)期和控氮條件對水培小白菜硝酸鹽含量的影響

21 、Most areas are for vegetable production, and a few for flower production.They are mainly eco-organic type soilless culture system, floating capillary hydroponics, NFT, DFH and Lu-SC system.───目前中國生產(chǎn)上使用的無(wú)土栽培系統主要為有機生態(tài)型無(wú)土栽培系統、浮板毛管法、NFT、DFH和魯-SC系統。

22 、Keywords industrializing aquaculture;vegetable hydroponics;water quality purification;───工廠(chǎng)化養殖;蔬菜水栽培;水質(zhì)凈化;

23 、Using the method of hydroponics which doesn't require soil, water is preserved in a closed loop system, eliminating the concern of agricultural runoff, and since it is continually recycled, the total water usage is 70% less than current requirements.─── 水培法不需要使用泥土 而是將水貯存在一個(gè)閉循環(huán)系統中 這樣就不用再擔心農田徑流帶來(lái)污染 而且因為水被不斷地回收利用 使用這種方法可以節省70%的水量

24 、Effects of Nutrient Conditions on Yield and Quality of Hydroponics Pumpkin───營(yíng)養條件對無(wú)土栽培西葫蘆產(chǎn)量和品質(zhì)的影響

25 、We also do business on hydroponics flowers, soilless culture device used for planting at home, design and construction of sighting agriculture project in greenhouse as well.───孫橋農業(yè)開(kāi)發(fā)區是首批國家級農業(yè)科技園區，國家引進(jìn)國外智力成果示范**基地。

26 、Techniques of hydroponics hybridization breeding of poplar───楊樹(shù)水培雜交育種技術(shù)

27 、Plant hydroponics and its application prospect in medicinal plants study───植物溶液培養及其在藥用植物研究中的應用展望

28 、For any of you sceptical about the limitations of hydroponic farming, here is a list of already commercially available products from hydroponically produced plants.─── 你若對水培法仍然持懷疑態(tài)度 可以參考此列表 上面是已經(jīng)能夠購買(mǎi)到的水培作物

29 、Hydroponics: A Practical Guide for the Soilless Grower, Second Edition───水栽法:無(wú)土生長(cháng)物實(shí)用指南

30 、Which means the hydroponics have been contaminated.─── 也就是說(shuō)水耕系統已經(jīng)受到污染

31 、In order to investigate the interaction of NH+4 with K+ in cotton seedlings,an hydroponics experiment containing three K+ concentrations(0.───在溶液培養條件下研究了NH+4+對棉花不同基因型幼苗干物質(zhì)積累以及K+吸收和利用的影響。

32 、Hydroponics culture───水培

33 、Preliminary Research on the Contrasting of Different Nutrient Solution in the Hydroponics of Flower Plant───花卉水培不同營(yíng)養液效果比較試驗初報

34 、Purification and utilization of turtle-breeding wastewater in Lactuca sativa var. Romana hydroponics system───生菜水培系統對養鱉廢水的凈化與利用

35 、Hydroponics of deep flow technique───深液流水培

36 、Crops would be irrigated by water recycled through the building's hydroponics system and without using soil, many diseases are ruled out - meaning no need for chemical pesticides.───農作物用該建筑物溶液培養系統的循環(huán)水進(jìn)行灌溉，而且沒(méi)有土壤，避免多種病害，也不需要任何化學(xué)殺蟲(chóng)劑。

37 、NewYork cityNew York City has an usual dementstration unusual demonstration farm for hydroponics.───紐約市有一個(gè)不同尋常的水栽法展示農場(chǎng)。

38 、Studies on Hydroponics Design and Its Effect of Vegetables on the Roof Platform of Buildings───樓頂平臺蔬菜水培系統設計及應用效果

39 、Hydroponics experiment───水培試驗

40 、Effect of Partial Replacement of Nitrate by Amino Acid and Urea on Nitrate Content of Nonheading Chinese Cabbage and Lettuce in Hydroponics───氨基酸和尿素替代硝態(tài)氮對水培不結球白菜和生菜硝酸鹽含量的影響

41 、Keywords heavy metal;adaptability of plant;hydroponics;simulated wastewater;───重金屬;植物適應性;漂浮栽培;模擬廢水;

42 、water culture(hydroponics)───(植物)水培

43 、different hydroponics gradients has no effect on budburst.───不同的水培梯度對芽體萌芽影響不大。

44 、The confection of the nutritious liquid is a important technical problem in the hydroponics .───營(yíng)養液配制是無(wú)土栽培一個(gè)關(guān)鍵的技術(shù)問(wèn)題。

45 、hydroponics n.───水栽法；

46 、We have phageresistance bacteria in the hydroponic lines to prevent that, which means that something got in and killed the good bacteria.─── 我們在水耕系統里加入了 噬菌體抗性菌株以避免這種情形 這代表有某種物質(zhì)滲入 并且殺死了有益菌

47 、New York City has a unusual demostration farm of hydroponics.───紐約市有一個(gè)特別的水培農場(chǎng)展示。

48 、New York City has an unusual demonstration farm for hydroponics.───紐約有一個(gè)特別的水培示范農場(chǎng)。

49 、From our brandnew hydroponic herb garden in the cafeteria to our solarpowered charging stations in the quad.─── 從餐廳的全新水培植物花園 到院子里的太陽(yáng)能充電站

50 、Flocco C G.Lobalbo A.Carranza M P.Giulietti A M Removal of Phenol by Alfalfa plants (Medicago sativa L.) grown in hydroponics and its effect on some physiological parameters 2002───宋玉芳.周啟星.許華夏.任麗萍.宋雪英.龔平菲、芘、1,2,4-三氯苯對土壤高等植物根伸長(cháng)抑制的生態(tài)毒性效應[期刊論文]-中國農業(yè)科學(xué)2002(11

51 、Description: hydroponic banana How to hydroponics(aquaponics) bananas 1, Can not use the soil .───如何種生態(tài)水耕香蕉 1、 不可以用土壤.會(huì )使植物根缺氧而腐爛。

52 、Still hydroponics───顯根水培

53 、Technical regulation of pollution-free cucumber hydroponics production───無(wú)公害黃瓜無(wú)土栽培生產(chǎn)技術(shù)規程

54 、Application of Plant Ecological Adaptability in Hydroponics───生態(tài)適應性在植物水生誘導上的運用

55 、This version of hydroponics uses an aquarium as a hatchery for freshwater fish, while vegetables grow on top in glass pods.───這個(gè)魚(yú)缸被用作淡水魚(yú)的孵化器，蔬菜生長(cháng)在上面的玻璃容器內。

56 、Effect of cerium(Ce3+) on photosynthesis in soybean seedlings was studied with hydroponics under laboratory conditions.───以大豆為實(shí)驗材料,用溶液培養試驗法研究稀土鈰(Ce3+)對大豆幼苗光合作用的影響。

57 、Let me turn on the lights and the hydroponics so you can get the full experience.─── 我來(lái)打開(kāi)燈和水培系統 你可以全方位體驗下

58 、Beef up the nutrient slurry in the hydroponics, and make version 2.0 a supertomato.─── 我可以增加水培養液里的營(yíng)養成分 種一個(gè)升級版超級番茄

59 、The Theory of Mineral Nutrition and Hydroponics───植物的礦質(zhì)營(yíng)養學(xué)說(shuō)與無(wú)土栽培

60 、Hydroponics Flower───水培花卉

61 、Improving aeration in hydroponics Principle and practice:───改善水培作物根際氧氣供給的原理和實(shí)踐

62 、Hydroponics euhture───水培條件

63 、Crops would be irrigated by water recycled through the building's hydroponics system and without using soil, many diseases are ruled out-meaning no need for chemical pesticides.───農作物用該建筑物溶液培養系統的循環(huán)水進(jìn)行灌溉，而且沒(méi)有土壤，避免多種病害，也不需要任何化學(xué)殺蟲(chóng)亮劑。

64 、The best outcome is that we grow healthy, strong plants that yield at the same rate as they would in standard hydroponics.───由于我們能夠平衡魚(yú)與植物對養分供需狀態(tài)，我們不需要換水，補充蒸散之消耗所做的補水量是很少的。

有關(guān)濕法**酸的5000字中英文翻譯

中文版的呢？

有關(guān)濕法**酸的5000字中英文翻譯

濕法**酸 wet -process phosphoric acid

資料

http://www.epa.gov/ttn/chief/ap42/ch08/final/c08s09.pdf

Phosphoric acid, also known as orthophosphoric acid or phosphoric(V) acid, is a mineral (inorganic) acid having the chemical formula H**O4. By contrast, orthophosphoric acid molecules can combine with themselves to form a variety of compounds referred to as phosphoric acids in a more general way. The term phosphoric acid can also refer to a chemical or reagent consisting of phosphoric acids, usually mostly orthophosphoric acid.

Orthophosphoric acid chemistry

Pure anhydrous phosphoric acid is a white solid that melts at 42.35 °C to form a colorless, viscous liquid.

Most people and even chemists refer to orthophosphoric acid as phosphoric acid, which is the IUPAC name for this compound. The prefix ortho is used to distinguish the acid from other phosphoric acids, called polyphosphoric acids. Orthophosphoric acid is a non-toxic, inorganic, rather weak triprotic acid, which, when pure, is a solid at room temperature and pressure. The chemical structure of orthophosphoric acid is shown above in the data table. Orthophosphoric acid is a very polar molecule; therefore it is highly soluble in water. The oxidation state of phosphorus (P) in ortho- and other phosphoric acids is +5; the oxidation state of all the oxygen atoms (O) is -2 and all the hydrogen atoms (H) is +1. Triprotic means that an orthophosphoric acid molecule can dissociate up to three times, giving up an H+ each time, which typically combines with a water molecule, H2O, as shown in these reactions:

H**O4(s) + H2O(l) ⇌ H3O+(aq) + H2PO4–(aq) Ka1= 7.5×10−3

H2PO4–(aq)+ H2O(l) ⇌ H3O+(aq) + HPO42–(aq) Ka2= 6.2×10−8

HPO42–(aq)+ H2O(l) ⇌ H3O+(aq) + PO43–(aq) Ka3= 2.14×10−13

The anion after the first dissociation, H2PO4–, is the dihydrogen phosphate anion. The anion after the second dissociation, HPO42–, is the hydrogen phosphate anion. The anion after the third dissociation, PO43–, is the phosphate or orthophosphate anion. For each of the dissociation reactions shown above, there is a separate acid dissociation constant, called Ka1, Ka2, and Ka3 given at 25°C. Associated with these three dissociation constants are corresponding pKa1=2.12 , pKa2=7.21 , and pKa3=12.67 values at 25°C. Even though all three hydrogen (H ) atoms are equivalent on an orthophosphoric acid molecule, the successive Ka values differ since it is energetically less favorable to lose another H+ if one (or more) has already been lost and the molecule/ion is more negatively-charged.

Because the triprotic dissociation of orthophosphoric acid, the fact that its conjugate bases (the phosphates mentioned above) cover a wide pH range, and, because phosphoric acid/phosphate solutions are, in general, non-toxic, mixtures of these types of phosphates are often used as buffering agents or to make buffer solutions, where the desired pH depends on the proportions of the phosphates in the mixtures. Similarly, the non-toxic, anion salts of triprotic organic citric acid are also often used to make buffers. Phosphates are found pervasively in biology, especially in the compounds derived from phosphorylated sugars, such as DNA, RNA, and adenosine triphosphate (ATP). There is a separate article on phosphate as an anion or its salts.

Upon heating orthophosphoric acid, condensation of the phosphoric units can be induced by driving off the water formed from condensation. When one molecule of water has been removed for each two molecules of phosphoric acid, the result is pyrophosphoric acid (H4P2O7). When an average of one molecule of water per phosphoric unit has been driven off, the resulting substance is a glassy solid having an empirical formula of HPO3 and is called metaphosphoric acid.[1] Metaphosphoric acid is a singly anhydrous version of orthophosphoic acid and is sometimes used as a water- or moisture-absorbing reagent. Further dehydrating is very difficult, and can be accomplished only by means of an extremely strong desiccant (and not by heating alone). It produces phosphoric anhydride, which has an empirical formula P2O5, although an actual molecule has a chemical formula of P4O10. Phosphoric anhydride is a solid, which is very strongly moisture-absorbing and is used as a desiccant.

[edit] pH and composition of a phosphoric acid solution

For a given total acid concentration [A] = [H**O4] + [H2PO4−] + [HPO42−] + [PO43−] ([A] is the total number of moles of pure H**O4 which have been used to prepare 1 liter of solution) , the composition of an aqueous solution of phosphoric acid can be calculated using the equilibrium equations associated with the three reactions described above together with the [H+][OH−] = 10−14 relation and the electrical neutrality equation. The system may be reduced to a fifth degree equation for [H+] which can be solved numerically, yielding:

[A] (mol/L) pH [H**O4]/[A] (%) [H2PO4−]/[A] (%) [HPO42−]/[A] (%) [PO43−]/[A] (%)

1 1.08 91.7 8.29 6.20×10−6 1.60×10−17

10−1 1.62 76.1 23.9 6.20×10−5 5.55×10−16

10−2 2.25 43.1 56.9 6.20×10−4 2.33×10−14

10−3 3.05 10.6 89.3 6.20×10−3 1.48×10−12

10−4 4.01 1.30 98.6 6.19×10−2 1.34×10−10

10−5 5.00 0.133 99.3 0.612 1.30×10−8

10−6 5.97 1.34×10−2 94.5 5.50 1.11×10−6

10−7 6.74 1.80×10−3 74.5 25.5 3.02×10−5

10−10 7.00 8.24×10−4 61.7 38.3 8.18×10−5

For large acid concentrations, the solution is mainly composed of H**O4. For [A] = 10−2, the pH is closed to pKa1, giving an equimolar mixture of H**O4 and H2PO4−. For [A] below 10−3, the solution is mainly composed of H2PO4− with [HPO42−] becoming non negligible for very dilute solutions. [PO43−] is always negligible.

[edit] Phosphoric acid as a chemical reagent

Pure 75-85% aqueous solutions (the most common) are clear, colourless, odourless, non-volatile, rather viscous, syrupy liquids, but still pourable. Phosphoric acid is very commonly used as an aqueous solution of 85% phosphoric acid or H**O4. Because it is a concentrated acid, an 85% solution can be corrosive, although nontoxic when diluted. Because of the high percentage of phosphoric acid in this reagent, at least some of the orthophosphoric acid is condensed into polyphosphoric acids in a temperature-dependent equilibrium, but, for the sake of labeling and simplicity, the 85% represents H**O4 as if it were all orthophosphoric acid. Other percentages are possible too, even above 100%, where the phosphoric acids and water would be in an unspecified equilibrium, but the overall elemental mole content would be considered specified. When aqueous solutions of phosphoric acid and/or phosphate are dilute, they are in or will reach an equilibrium after a while where practically all the phosphoric/phosphate units are in the ortho- form.

[edit] Preparation of hydrogen halides

Phosphoric acid reacts with halides to form the corresponding hydrogen halide gas (steamy fumes are observed on warming the reaction mixture). This is a common practice for the laboratory preparation of hydrogen halides.

3NaCl(s) + H**O4(l) → NaH2PO4(s) + HCl(g)

3NaBr(s) + H**O4(l) → NaH2PO4(s) + HBr(g)

3NaI(s) + H**O4(l) → NaH2PO4(s) + HI(g)

[edit] Rust removal

Phosphoric acid may be used by direct application to rusted iron, steel tools, or surfaces to convert iron(III) oxide (rust) to a water-soluble phosphate compound. It is usually available as a greenish liquid, suitable for dipping (acid bath), but is more generally used as a component in a gel, commonly called naval jelly. As a thick gel, it may be applied to sloping, vertical, or even overhead surfaces. Care must be taken to avoid acid burns of the skin and especially the eyes, but the residue is easily diluted with water. When sufficiently diluted, it can even be nutritious to plant life, containing the essential nutrients phosphorus and iron. It is sometimes sold under other names, such as "rust remover" or "rust killer." It should not be directly introduced into surface water such as creeks or into drains, however. After treatment, the reddish-brown iron oxide will be converted to a black iron phosphate compound coating that may be scrubbed off. Multiple applications of phosphoric acid may be required to remove all rust. The resultant black compound can provide further corrosion resistance (such protection is somewhat provided by the superficially similar Parkerizing and blued electrochemical conversion coating processes.) After application and removal of rust using phosphoric acid compounds, the metal should be oiled (if to be used bare, as in a tool) or appropriately painted, by using a multiple coat process of primer, intermediate, and finish coats.

[edit] Processed food use

Food-grade phosphoric acid is used to acidify foods and beverages such as various colas, but not without controversy regarding its health effects. It provides a "tangy" taste, and, being a mass-produced chemical, is available cheaply and in large quantities. The low cost and bulk availability is unlike more expensive natural seasonings that give comparable flavors, such as ginger for tangyness, or citric acid for sourness, obtainable from lemons and limes. (However most citric acid in the food industry is not extracted from citrus fruit, but fermented by Aspergillus niger mold from scrap molasses, waste starch hydrolysates and phosphoric acid.) It is labeled as E number E338.

[edit] Biological effects on bone calcium and kidney health

Phosphoric acid, used in many soft drinks (primarily cola), has been linked to lower bone density in epidemiological studies. For example, a study[2] using dual-energy X-ray absorptiometry rather than a questionnaire about breakage, provides reasonable evidence to support the theory that drinking cola results in lower bone density. This study was published in the American Journal of Clinical Nutrition. A total of 1672 women and 1148 men were studied between 1996 and 2001. Dietary information was collected using a food frequency questionnaire that had specific questions about the number of servings of cola and other carbonated beverages and that also made a differentiation between regular, caffeine-free, and diet drinks. The paper cites significant statistical evidence to show that women who consume cola daily have lower bone density. Total phosphorus intake was not significantly higher in daily cola consumers than in nonconsumers; however, the calcium-to-phosphorus ratios were lower. The study also suggests that further research is needed to confirm the findings.

On the other hand, a study funded by Pepsi suggests that low intake of phosphorus leads to lower bone density. The study does not examine the effect of phosphoric acid, which binds with magnesium and calcium in the digestive tract to form salts that are not absorbed, but, rather, it studies general phosphorus intake.[3]

However, a well-controlled clinical study by Heaney and Rafferty using calcium-balance methods found no impact of carbonated soft drinks containing phosphoric acid on calcium excretion.[4] The study compared the impact of water, milk, and various soft drinks (two with caffeine and two without; two with phosphoric acid and two with citric acid) on the calcium balance of 20- to 40-year-old women who customarily consumed ~3 or more cups (680 ml) of a carbonated soft drink per day. They found that, relative to water, only milk and the two caffeine-containing soft drinks increased urinary calcium, and that the calcium loss associated with the caffeinated soft drink consumption was about equal to that previously found for caffeine alone. Phosphoric acid without caffeine had no impact on urine calcium, nor did it augment the urinary calcium loss related to caffeine. Because studies have shown that the effect of caffeine is compensated for by reduced calcium losses later in the day,[5] Heaney and Rafferty concluded that the net effect of carbonated beverages – including those with caffeine and phosphoric acid - is negligible, and that the skeletal effects of carbonated soft drink consumption are likely due primarily to milk displacement.

Other chemicals such as caffeine (also a significant component of popular common cola drinks) were also suspected as possible contributors to low bone density, due to the known effect of caffeine on calciuria. One other study, comprised of 30 women over the course of a week, suggests that phosphoric acid in colas has no such effect, and postulates that caffeine has only a temporary effect, which is later reversed. The authors of this study conclude that the skeletal effects of carbonated beverage consumption are likely due primarily to milk displacement.[4] (Another possible confounding factor may be an association between high soft drink consumption and sedentary lifestyle.)

Cola consumption has also been linked to chronic kidney disease and kidney stones through medical research.[6] This study differentiated between the effects of cola (generally contains phosphoric acid), non-cola carbonated beverages (substitute citric acid) and coffee (control for caffeine), and found that drinking 2 or more colas per day more than doubled the incidence of kidney disease.

[edit] Medical use

Phosphoric acid is used in dentistry and orthodontics as an etching solution, to clean and roughen the surfaces of teeth where dental appliances or fillings will be placed. Phosphoric acid is also an ingredient in over-the-counter anti-nausea medications that also contain high levels of sugar (glucose and fructose). It should not be used by diabetics without consultation with a doctor. This acid is also used in teeth whiteners to eliminate any plaque that may be on your teeth.

[edit] Preparation of phosphoric acid

Phosphoric acid can be prepared by two routes - the Thermal Process and the Wet Process.

Thermal phosphoric acid: This very pure phosphoric acid is obtained by burning elemental phosphorus to produce phosphorus pentoxide and dissolving the product in dilute phosphoric acid. This produces a very pure phosphoric acid, since most impurities present in the rock have been removed when extracting phosphorus from the rock in a furnace. The end result is food-grade, thermal phosphoric acid; however, for critical applications, additional processing to remove arsenic compounds may be needed.

Wet phosphoric acid: Wet process phosphoric acid is prepared by adding sulfuric acid to calcium phosphate rock.

The simplified reaction is:

3 H2SO4 + Ca3(PO4)2 + 6 H2O ↔ 2 H**O4 + 3 CaSO4.2H2O

Wet-process acid can be purified by removing fluorine to produce animal-grade phosphoric acid, or by solvent extraction and arsenic removal to produce food-grade phosphoric acid.

[edit] Other applications

Phosphoric acid is used as the electrolyte in phosphoric-acid fuel cells. It is also used as an external standard for phosphorus-31 nuclear magnetic resonance (NMR).

Phosphoric acid is used as a cleaner by construction trades to remove mineral deposits, cementitious smears, and hard water stains. It is also used as an ingredient in some household cleaners aimed at similar cleaning tasks.

Hot phosphoric acid is used in microfabrication to etch silicon nitride (Si3N4). It is highly selective in etching Si3N4 instead of SiO2, silicon dioxide. [7]

Phosphoric acid is used as a flux by hobbyists (such as model railroaders) as an aid to soldering.

Phosphoric acid is also used in hydroponics pH solutions to lower the pH of nutrient solutions. While other types of acids can be used, phosphorus is a nutrient used by plants, especially during flowering, making phosphoric acid particularly desirable. General Hydroponics pH Down liquid solution contains phosphoric acid in addition to citric acid and ammonium bisulfate with buffers to maintain a stable pH in the nutrient reservoir.

Phosphoric acid is used as a pH adjuster in cosmetics and skin-care products.[8]

Phosphoric acid is used as a chemical oxidizing agent for activated carbon production.[9]

Phosporic acid is also used for High Pressure Liquid Chromotography.