Overview
The potassium dichromate method is a standard analytical procedure for measuring chemical oxygen demand (COD), a critical parameter in assessing water pollution levels. This method involves the oxidation of organic and inorganic substances in a water sample by potassium dichromate in a strongly acidic solution. The amount of dichromate consumed is proportional to the oxygen demand, providing a quantitative measure of pollutants. The method is widely adopted in environmental laboratories and industrial settings due to its robustness and compatibility with automated systems. It is particularly effective for wastewater with high organic content, though it requires careful handling due to the toxic nature of hexavalent chromium (Cr⁶⁺).
Physical and Chemical Properties
Potassium dichromate (K₂Cr₂O₇) is an inorganic compound with vivid orange-red crystals. It is highly soluble in water, forming a stable acidic solution that serves as a potent oxidizing agent. The compound decomposes at 500°C, releasing oxygen and forming chromium(III) oxide. In the COD test, the dichromate ion (Cr₂O₇²⁻) oxidizes organic matter at high temperatures (typically 150°C) in the presence of sulfuric acid and silver sulfate catalyst. The reaction converts Cr⁶⁺ to Cr³⁺, with a distinct color change from orange to green, which is measured spectrophotometrically.
Main Applications
This method is primarily used for COD analysis in environmental monitoring, wastewater treatment plants, and industrial effluent testing. Regulatory agencies worldwide recognize it as a benchmark for compliance with water quality standards. Beyond environmental applications, the potassium dichromate method is employed in research to study oxidative degradation of organic compounds. Its high oxidation efficiency (up to 95-100% for many organics) makes it superior to alternative methods like permanganate oxidation.
Safety and Storage
Potassium dichromate is classified as a carcinogen and acute toxin. Laboratories must follow strict protocols, including fume hood use, chemical-resistant gloves, and proper waste disposal for chromium-containing residues. Storage requires airtight containers in ventilated areas, segregated from organic materials and reducing agents. Spill kits with reducing agents (e.g., sodium thiosulfate) should be readily available to neutralize accidental releases.
B2B Procurement Guide
When sourcing potassium dichromate for COD testing, prioritize suppliers with ISO 9001 certification and batch-specific certificates of analysis. Key specifications include ≥99.5% purity and low heavy metal impurities. For high-throughput labs, pre-prepared COD reagent vials (with dichromate, acid, and catalyst) offer convenience but at a premium cost. Bulk purchases of 25 kg drums may reduce costs by approximately 20-30% for large-scale operations.
Related Manufacturers
- 主营：COD测量仪、氨氮测定仪、总磷测定仪、水质检测仪、多参数水质检测仪、总氮测定仪、更携式COD测定仪、便携式氨氮测定仪、便携式总磷测定仪、便携式总氮测定仪、水质测定仪、多参数水质测定仪、测油仪、红外测油仪、红外分光测油仪、紫外测油仪、便携式测油仪、全自动测油仪、全自动红外测油仪、全自动紫外测油仪、全自动红外分光测油仪、全自动紫外分光测油仪、总余氯测定仪、总余氯快速测定仪、水质分析器
- 主营：全自动凯氏定氮仪、红外测油仪、BOD测定仪、台式多参数水质检测仪、重金属检测仪、农药残留检测仪、电厂专用硅酸根检测仪、便携式多参数水质检测、紫外多参数检测仪、综合重金属检测仪、食品安全测定仪、液液萃取仪、一体化万用蒸馏仪、紫外测油仪、磷酸根测定仪、粗纤维测定仪、测脂肪测定仪、全自动电位滴定仪、离子计、COD测定仪、余氯测定仪、光度计、溶解氧仪、水质理化箱、滴定仪
- 主营：voc测试仪、油烟测试仪、自动监测仪、检测仪、气体检测仪、环境检测仪、油烟分析仪、油烟监测仪、大气采样器、水质分析仪、烟气分析仪、明渠流量计、水质采样器
- 主营：恒湿称重系统、油烟监测仪、光散射、voc检测仪、油烟检测仪、水质检测仪、烟气检测仪、气体检测仪、回收检测仪、粉尘检测仪、测定仪、cod消解、粉尘连续、自动采样器、大气采样器、采样测试仪、水质采样器、在线分析仪、烟气含湿量、烟气分析仪、内置锂电池、自动分析仪、激光粉尘仪、氧化碳分析仪、氟化物采样器
- 主营：培养箱、分析仪、报警仪、检测仪、室内检测仪器、甲醛检测、振动检测分析仪、环保第三方检测、环境检测、测量仪、酸度计、风速仪、蓝牙、称重系统、测定仪、声校准器、酸碱浓度计、流量计、采样器、消解器、机器人、测试仪、防护包、生物安全柜、浊度仪
- 主营：纺织品、覆面材料、纺织面料、检测技术、检测中心、检测平台、检测设备、纤维检测、检测实验室、五氯苯酚、儿童服装、童装绳索、服装机械、儿童服饰安全
- 主营：水质采样器、水质分析仪、烟尘烟气测试仪、气体检测仪、油气回收检测仪、大气采样器、超声波明渠流量计、恒温恒湿称重系统、个人防护包
- 主营：分析仪、采样器、监测仪、检测箱、检测仪、车尾检测、压力计、烟度计、流量计、直读仪、传感器、速测仪、消解仪、报警仪、测油仪、溶解氧仪、流量校准器、恒温加热器、水质测定仪、表面沾污仪、数字风速仪、细菌培养箱、生物培养箱、火焰模拟器、智能采样仪
- 主营：水质分析仪、水质采样器、大气采样器、气体检测仪、粉尘颗粒物检测仪、油气回收检测仪、VOC检测仪、甲醛检测仪、ATP荧光检测仪、烟尘烟气分析仪、流量校准仪、林格曼黑度仪、FID、红外CO/CO2分析、激光甲烷遥距仪、明渠流量计、风速仪、TOC总有机碳分析仪、汽车尾气分析仪、红外测油仪、恒温恒湿称重系统
- 主营：单人防护装备包、个人防护包、水污染监测设备、移动执法装备、移动执法包、油烟检测仪、VOC检测仪、移动源执法设备、OBD检测仪、FID检测仪、红外气体泄漏检测仪、红外夜视仪、热成像仪、便携式超声波明渠流量、qdf-6风速仪、恒流大气采样器、在用车尾气分析仪、不透光烟度计、车用氮氧化物分析仪、便携式水质自动采样器、水质快检试剂包、多普勒流量计、转子流速仪、紫外线强度仪
- 主营：全自动凯氏定氮仪、红外测油仪、国标BOD测定仪、多参数水质检测仪、食品安全检测仪、cod检测仪、水质重金属检测仪、土壤肥料养分检测仪、便携式多参数检测仪、农残检测仪、水质微生物采样检测箱、溶解氧检测仪、高锰酸盐指数分析仪、光度计、水分仪、脂肪测定仪、粗纤维测定仪、紫外测油仪、滴定仪、全自动电位滴定仪、电厂锅炉水硅酸根测定、磷酸根测定仪、水质理化箱、全自动总磷测定仪
- 主营：分析仪、采样器、监测仪、检测仪、消解器、粉尘仪、回流管、防护箱、测量仪、培养箱、风速仪、黑度仪、微波炉、测定仪、遥测仪、萃取仪、指数仪、流量计、防护包、测油仪、真空泵、无氧培养、加热装置、水质监测、光电光度
- 主营：单人防护装备、不透光烟度计、氮氧化物分析仪、生态环境执法装备、移动执法包、移动源执法设备、水质多参数检测仪、cod检测仪、不分光红外气体检测仪、油烟检测仪、氢火焰离子检测仪、obd诊断仪、烟尘烟气测试仪、超声波明渠流量计、多普勒流速仪、热电风速仪、空气微生物采样器、照度计、大气环境采样器、粉尘仪、恒流空气采样器、水质自动采样器、林格曼黑度计
- 主营：水质传感器电极探头、TOC总有机碳分析仪、浮游菌采样器、在线氨氮检测仪、在线水质检测仪、在线总磷检测仪、在线总氮检测仪、在线COD检测仪、余氯检测仪、电导率检测仪、水质快速检测试剂盒、真菌毒素检测仪、车用尿素检测仪、二次供水水质检测仪、水产养殖检测仪、生物毒性检测仪、BOD检测仪、地下管网水质检测仪、浮标水质监测系统、尘埃粒子计数器、COD传感器、ph电极、电磁流量计、氮吹仪、风量仪风量罩
- 主营：水质检测仪、明渠流量计、在线水质采样器