Activated carbon possesses adsorption properties for organic matter in water. Due to its well-developed pore structure and large specific surface area, it exhibits strong adsorption capabilities for dissolved organic pollutants in water, such as benzene compounds, phenolic compounds, petroleum, and petroleum products. Moreover, it effectively removes organic pollutants that are difficult to eliminate by biological and other chemical methods, including color, peculiar odors, methyl blue surfactants, herbicides, pesticides, agricultural chemicals, synthetic detergents, synthetic dyes, amines, and many other artificially synthesized organic compounds.
Activated carbon's adsorption of Cr(VI)
With the rapid development of electroplating industry, a large amount of electroplating wastewater poses increasingly severe harm to the human environment. Chromium(VI) is abundant in chromium-containing electroplating wastewater, and if not treated before discharge, it can severely pollute the environment upon which humans depend. Activated carbon possesses highly developed microporous structures and a high specific surface area, with strong physical adsorption capabilities, effectively adsorbing Cr(VI) from wastewater. Additionally, the surface of activated carbon contains numerous oxygen-containing groups such as hydroxyl (-OH) and carboxyl (-COOH), which possess electrostatic adsorption functions and exhibit chemical adsorption on Cr(VI), making it suitable for treating Cr(VI) in electroplating wastewater. Studies have shown that for wastewater with a pH of 4-5 and a 50 mL Cr(VI) concentration of 100 mg/L, when 2g of activated carbon is used, after 1 hour of oscillation adsorption, the Cr(VI) concentration in the effluent reaches 0.38 mg/L, meeting the higher permissible Cr(VI) discharge concentration requirements as specified in the wastewater discharge standard (GB8978.1996).
Two activated carbon treatment of Qing wastewater
The electroplating industry, coking industry, purification of blast furnace gas, gold and silver ore beneficiation, and other sectors all emit pollutants.qingWastewater.qingChemical substances transformed into highly toxic materials pose significant dangers to humans and fish. Due to its large specific surface area, activated carbon is effective in...qingWastewater also exhibits good adsorption treatment effects. Tests have shown that: for a certain gold mine containing...qingWastewater, Total WastewaterqingChemical (CN') concentration was measured at 389.90 m2/L, with a water treatment volume of 26.3 mL and 1g of activated carbon. The adsorption volume of CN' was 10.24 m2/L, resulting in an effluent CN' concentration below 0.5 m2/L, with an adsorption removal rate of 99.9%. Additionally, research indicates that soaking activated carbon in 3% copper chloride or 5% copper sulfate, followed by rinsing and drying, then packing into columns, can enhance the removal efficiency.qingEfficiency Doubled to Tripled: When controlling the incoming water pH between 6-9, most of CN' is in complexed state, while activated carbon is effective in complexation.qingThe adsorption capacity of inorganic compounds is compared to that of simple compounds.qingThe substance has strong adsorption capacity.
Three activated carbon treatments for mercury-containing wastewater
In the chlor-alkali industry, mercury is used as the cathode to produce chlorine gas and caustic soda; the synthesis industries of polyvinyl chloride, acetaldehyde, and vinyl acetate also utilize mercury as a catalyst; the electronics instrument industry frequently employs mercury as well, thus these industries all discharge mercury-containing wastewater. Mercury has severe toxic effects on the human body, with methylmercury accumulating in the brain tissue, disrupting neural functions, and in severe cases, leading to death. Activated carbon can effectively adsorb mercury from wastewater, and some factories have adopted this method to treat mercury-containing wastewater, although it is more suitable for low-concentration mercury wastewater. When the mercury concentration in wastewater is high, it can be pre-treated to reduce the mercury concentration before using activated carbon for adsorption. Wastewater with mercury concentrations below 1mg/L to 2mg/L can pass through an activated carbon filter tower, reducing the mercury content in the effluent to between 0.01mg/L and 0.05mg/L. After mercury recovery, activated carbon can be regenerated and reused. For instance, in an electrolytic factory where the mercury concentration in wastewater ranges from 5mg/L to 10mg/L, the treatment process involves first adding ferrous sulfate and sodium sulfide to react, then separating the precipitate in a sedimentation tank, which reduces the mercury concentration in the supernatant to between 0.1mg/L and 1.0mg/L. Subsequently, the wastewater is passed through a granular activated carbon column, where the mercury content is further reduced to between 0.01mg/L and 0.05mg/L. Activated carbon has a higher adsorption and removal capacity for organic mercury than inorganic mercury. The removal rate of mercury increases with a decrease in pH value. It is reported that pretreating activated carbon with a carbon disulfide solution can significantly enhance its mercury removal capacity. Studies show that activated carbon treated with carbon disulfide can reduce the mercury concentration in wastewater from an initial 10.0g/L to 2.1.g/L, with the best treatment effect occurring at a pH of 10.
Four Activated Carbon Treatment of Phenolic Waste Water
Phenol-containing wastewater is widely sourced from petrochemical plants, plastic factories, synthetic fiber plants, coking plants, textile factories, nitrogen production plants, and oil refining plants. Activated carbon has good adsorption properties for phenol and can successfully treat phenol-containing wastewater. For high-concentration phenol-containing wastewater, when the phenol concentration in the influent water reaches 1950 mg/L, the phenol concentration in the effluent can be reduced to below 0.1 mg/L through a series of three activated carbon adsorption columns. However, the adsorption columns are quickly penetrated by phenol. Therefore, activated carbon is more suitable for treating medium and low-concentration phenol-containing wastewater. When the phenol influent concentration is between 0.12 mg/L and 44 mg/L, the removal rate of phenol can reach over 99%, with the effluent phenol concentration being less than 0.1 mg/L. Tests show that for coking wastewater with an influent phenol concentration of 427 mg/L to 547 mg/L, when the dosage of powdered activated carbon is 402 L, aeration for 2 hours can reduce the phenol content in the coking wastewater to below 0.5 mg/L, meeting discharge standards. Activated carbon adsorbs phenol under acidic and neutral conditions and is regenerated under alkaline conditions.
Five activated carbon treatment of dye wastewater
The development of the textile industry has spurred the growth of dye production. Surveys show that over 700,000 tons of dyes are produced worldwide each year, with 2% discharged directly into water bodies as wastewater, and another 10% lost during subsequent textile dyeing processes. Wastewater from dyes is complex, with varying water quality, high chromaticity, and high concentration, making it difficult to treat. The chromaticity in water affects the photosynthesis of aquatic plants, thus disrupting the ecological balance. The large specific surface area of activated carbon allows for effective removal of chromaticity from wastewater. Studies have shown that for solutions of methyl orange, crystal violet, direct fast black G, and active brilliant blue with an initial concentration of 30mg/L, at pH=7, with an aeration rate of 1m3/h, and an addition of 6g/L of powdered activated carbon for a 20-minute adsorption time, the removal rate for the four dyes was between 97% and 99%. For acidic fuchsin, basic fuchsin, and active black B-133 dye wastewater with an initial concentration of 250mg/L, when coconut shell activated carbon was added at 0.8%, 1.0%, and 2.0%, respectively, and the adsorption time was 3.5h, 6h, and 17h, the decolorization rate exceeded 97%, the dilution factor of the effluent chromaticity was not greater than 50, and the COD was less than 50mg/L, meeting the effluent standards (GB8978—1996) for wastewater discharge. For a pH range of 7.5 to 12.5, the change in pH does not significantly affect the adsorption rate of activated carbon for a considerable number of dyes. Regeneration of activated carbon after dye adsorption is also relatively easy. Experiments indicate that activated carbon fibers, granular activated carbon, and coconut shell activated carbon used to treat simulated dye wastewater, after being dried at 120°C for 12 hours and then microwave regenerated for 10 seconds, the adsorption performance of granular activated carbon and coconut shell activated carbon was restored to 100% of the original, while the adsorption capacity of activated carbon fibers reached 2.4 times the original amount.
