Boric acid, กรดบอริก, บอริกแอซิด, บอริคแอซิด

Boric acid, บอริกแอซิด, กรดบอริก

กรดบอริก

เป็นสารใส ไม่มีสี ไม่มีกลิ่น เป็นผลึกหรือผงสีขาว บางครั้งเป็นเงาคล้ายไข่มุก

ละลายได้ดีในน้ำและแอลกอฮอล์ จะละลายได้ดียิ่งขึ้นในน้ำร้อนและกลีเซอรอล

กรดบอริกจะระเหยในไอน้ำเมื่อให้ความร้อนถึง 100 องศาเซลเซียส จะสุญเสียน้ำและค่อยๆ เปลี่ยนเป็นเมตาบอริกแอซิด อุณหภูมิ 140 องศาเซลเซียส จะเปลี่ยนเป็นเตตราบอริกแอซิด และที่อุณหภูมิสูงๆ จะเปลี่ยนเป็นโบรอนไตรออกไซด์ (boron trioxide, B2O3) กรดบอริก (boric Acid) ใช้เป็นสารต้านจุลชีพ (antiseptic) เป็นวัตถุกันเสีย (preservative) และใช้เป็นตัวหยุดยั้งการเจริญของเชื้อรา (mold) ในแป้งทาตัว ประกาศกระทรวงสาธารณสุขฉบับที่ 151 (พ.ศ. 2536) เรื่องวัตถุที่ห้ามใช้ในอาหารกรดบอริก เป็นวัตถุที่ห้ามใช้ในอาหาร (prohibit substances) เป็นอันตรายในอาหาร (food hazard) ประเภทอันตรายทางเคมี (chemical hazard) ทั้งบอร์แรกซ์และกรดบอริกมีคุณสมบัติการดูดซึม การขับถ่าย และพิษที่เกิดขึ้นคล้ายคลึงกัน บอริคแอซิ ด (H3BO3) : ช่วยในการเคลื่อนย้ายน้ำตาลไปยั งส่วนต่างๆ ของพื ช ถ้ าขาดสารกลุ่มนี้ พืชจะโตผิดปกติ  หรือหยุดการเจริ ญเติบโต Boric Acid (boracic

acid):  White or colorless, smooth

crystals or powder, soluble in water, alcohol and glycerin. คุณประโยชน์: เป็นสารเคมีที่ใช้ในอุสาหกรรมเซรามิก, ซิเมนต์, สารประกอบวัตถุกันเสียในอาหาร, เป็นสารสำหรับหนังรวมทั้งการตกแต่งและสารประกอบในการจัดทำหนังก่อนที่จะมีการฟอกหนัง, อัญมนีเทียม, อุตสาหกรรมสี สีเคลือบ, เคลือบกระดาษ, เครื่องสำอาง, สบุ่, ยา, สิ่งทอ

Boric

acid, also called hydrogen borate, boracic acid, orthoboric acid and acidum

boricum, is a weak acid of boron often used as an antiseptic, insecticide,

flame retardant, neutron absorber, or precursor to other chemical compounds. It

has the chemical formula H3BO3 (sometimes written B(OH)3), and exists in the

form of colorless crystals or a white powder that dissolves in water. When

occurring as a mineral, it is called sassolite. 

Uses

Medical

Boric

acid can be used as an antiseptic for minor burns or cuts and is sometimes used

in dressings or salves. Boric acid is applied in a very dilute solution as an

eye wash. Dilute boric acid can be used as a vaginal douche to treat bacterial

vaginosis due to excessive alkalinity. As an antibacterial compound, boric acid

can also be used as an acne treatment. It is also used as prevention of

athlete's foot, by inserting powder in the socks or stockings, and in solution

can be used to treat some kinds of otitis externa (ear infection) in both

humans and animals. The preservative in urine sample bottles in the UK is boric

acid.

Boric

acid solutions used as an eye wash or on abraded skin are known to be toxic,

particularly to infants, especially after repeated use; this is because of its

slow elimination rate.

Insecticidal

Boric

acid was first registered in the US as an insecticide in 1948 for control of cockroaches,

termites, fire ants, fleas, silverfish, and many other insects. The product is

generally considered to be safe to use in household kitchens to control

cockroaches and ants. It acts as a stomach poison affecting the insects'

metabolism, and the dry powder is abrasive to the insects' exoskeletons.

Preservation

In

combination with its use as an insecticide, boric acid also prevents and

destroys existing wet and dry rot in timbers. It can be used in combination

with an ethylene glycol carrier to treat external wood against fungal and

insect attack. It is possible to buy borate-impregnated rods for insertion into

wood via drill holes where dampness and moisture is known to collect and sit.

It is available in a gel form and injectable paste form for treating rot

affected wood without the need to replace the timber. Concentrates of

borate-based treatments can be used to prevent slime, mycelium, and algae

growth, even in marine environments.

Boric

acid is added to salt in the curing of cattle hides, calfskins, and sheepskins.

This helps to control bacteria development, and helps to control insects.

Lubrication

Colloidal

suspensions of nanoparticles of boric acid dissolved in petroleum or vegetable

oil can form a remarkable lubricant on ceramic or metal surfaces[19] with a

coefficient of sliding friction that decreases with increasing pressure to a

value ranging from 0.10 to 0.02. Self-lubricating H3BO3 films result from a

spontaneous chemical reaction between water molecules and B2O3 coatings in a humid

environment. In bulk-scale, an inverse relationship exists between friction

coefficient and Hertzian contact pressure induced by applied load.

Boric acid is used to lubricate carrom and novuss boards, allowing for faster play.

Nuclear power

Boric

acid is used in nuclear power plants as a neutron poison to slow down the rate

at which fission is occurring. Fission chain reactions are generally driven by

the amount of neutrons present (as products from previous fissions). Natural

boron is 20% boron-10 and about 80% boron-11. Boron-10 has a high cross-section

for absorption of low energy (thermal) neutrons. By adding more boric acid to

the reactor coolant which circulates through the reactor, the probability that

a neutron can survive to cause fission is reduced. Therefore, changes in boric

acid concentration effectively regulate the rate of fission taking place in the

reactor. This method is only used in pressurized water reactors (PWRs). Boron

is also dissolved into the spent fuel pools containing used uranium rods. The

concentration is high enough to keep neutron multiplication at a minimum. Boric

acid was dumped over Reactor 4 of the Chernobyl Nuclear Power Plant after its

meltdown to prevent another reaction from occurring.

Industrial

The

primary industrial use of boric acid is in the manufacture of monofilament

fiberglass usually referred to as textile fiberglass. Textile fiberglass is

used to reinforce plastics in applications that range from boats, to industrial

piping to computer circuit boards. In the jewelry industry, boric acid is often

used in combination with denatured alcohol to reduce surface oxidation and

firescale from forming on metals during annealing and soldering operations.

Boric acid is used in the production of the glass in LCD flat panel displays.

In

electroplating, boric acid is used as part of some proprietary formulas. One

such known formula calls for about a 1 to 10 ratio of H3BO3 to NiSO4, a very

small portion of sodium lauryl sulfate and a small portion of H

 2SO4. Boric acid, mixed with borax (sodium

tetraborate decahydrate) at the weight ratio of 4:5, is highly soluble in

water, though they are not so soluble separately. The solution is used for fire

retarding agent of wood by impregnation. It is also used in the manufacturing

of ramming mass, a fine silica-containing powder used for producing induction

furnace linings and ceramics. Boric acid is one of the most commonly used

substances that can neutralize active hydrofluoric acid (HF). It works by

forcing the free F? anions into

complex salts. This process defeats the extreme toxicity of hydrofluoric acid,

particularly its ability to sequester ionic calcium from blood serum which can

lead to cardiac arrest and bone decomposition; such an event can occur from

just minor skin contact with HF. Boric acid is added to borax for use as

welding flux by blacksmiths. Boric acid, in combination with silicone oil, is

used to manufacture Silly Putty. Boric acid, in combination with eighty other

chemicals, is used in Marcellus Shale hydraulic fracturing.

Pyrotechnics

Boron

is used in pyrotechnics to prevent the amide-forming reaction between aluminum

and nitrates. A small amount of boric acid is added to the composition to

neutralize alkaline amides that can react with the aluminum. Boric acid can be

used as a colorant to make fire green. For example, when dissolved in methanol

it is popularly used by fire jugglers and fire spinners to create a deep green

flame.

 

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