Abstract
In terms of health, dyes have carcinogenic, mutagenic and toxic properties and can have adverse effects on health and the environment. Therefore, sewage containing to dyes must be purified before being discharged into the environment. The current study aimed to investigate the effectiveness of Alcea rosea root extract in Disperse red 60 and Reactive blue 19 dyes removal from synthetic sewage. In this study, the effect of different indices including pH (5–11), Alcea rosea concentration (50–300 mg/L) and initial dye concentration (10–80 mg/L) was investigated. During the tests, the coagulant was stirred with rapid mixing at a speed of 250 rpm for 2 min. In the following, the speed (30–60 rpm) and the time (10–25 min) were used for slow mixing and after mixing the effect of settling time (10–60 min) and temperature (20–70) on removal efficiency of Disperse and Reactive dyes was investigated. The results showed that the maximum of removal efficiency of Disperse and Reactive dyes in optimum conditions including (pH = 11, coagulant concentration = 200 and 250 mg/L, dye concentration 40 and 20 mg/L, speed 60 rpm, during 15 min with settling time 60 min and temperature 60 °C obtained 86% and 68%, respectively. According to the result, the Alcea rosea coagulant has the best ability in removing dyes from aqueous solutions and sewage, especially Disperse dyes. Disperse dye is much eliminated in the coagulation process due to its lower solubility, higher suspending materials and less required solved chemical oxygen demand to the total chemical oxygen demand (SCOD/TCOD).
Highlights
In recent years, development of industries has been caused environmental pollution because there are organic and inorganic pollutants, heavy metals, dyes, etc. in their sewage from production process (Santhi et al 2016)
The results showed that the highest removal of Disperse dye with 75% efficiency was obtained at 40 mg/L of dye concentration
The maximum Reactive dye removal efficiency was achieved with 56.8% efficiency at a concentration of 20 mg/L
Summary
Development of industries has been caused environmental pollution because there are organic and inorganic pollutants, heavy metals, dyes, etc. in their sewage from production process (Santhi et al 2016). Development of industries has been caused environmental pollution because there are organic and inorganic pollutants, heavy metals, dyes, etc. Due to the complicated and non-biodegradable molecular structure, dye is the most important pollutants in the industries, that can’t be removed by biological methods (Cengiz et al 2012). The chemical purification procedure can be useful in the removal of this contaminant (Chen et al 2018). Annual production of dyes is estimated at more than 700,000 tones (Moussavi and Mahmoudi 2009). Three dyes that commonly used in industries, and based on their chemical nature are classified as follows: acidic, Reactive and Disperse Dyes. Acidic dyes are water-soluble and Anionic compounds that used for nylon, wool, and silk fibers (Phalakornkule et al 2010). Disperse dyes are part of the derivatives of nitro-phenyl
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