Abstract
Recently, rapid industrialization leads to excessive release of heavy metals such as Cr(VI) in the environment. Exposure to chromium (VI) can cause kidney and liver damage, depressed immune systems, and a variety of cancers. Therefore, treatment of Cr(VI) containing wastewater is mandatory. This study aims to optimize the removal of Cr(VI) from aqueous solution using locally available Teff husk activated carbon adsorbent. The laboratory-based study was conducted on the optimization of Cr(VI) removal efficiency of Teff husk activated carbon from aqueous solution. A central composite design was used to examine the effect of the interaction of process parameters and to optimize the process using Design Expert version 7.0 software. The optimized removal efficiency of Teff husk activated carbon (95.597%) was achieved at 1.92 pH, 87.83 mg/L initial concentration, 20.22 g/L adsorbent dose, and 2.07 H contact time. The adsorption of Cr(VI) on Teff husk activated carbon was found to be best fitted with pseudo-second-order kinetics and Langmuir isotherm model of the adsorption. Teff husk activated carbon can be used as an efficient adsorbent for removal of chromium (VI) from contaminated water. Column adsorption needs to be studied in the future.
Highlights
The generation rate of wastewater is increasing dramatically worldwide due to the increased consumption of water
The physicochemical characteristics of THAC (Table 3) show as the prepared activated carbon has good quality to be used as an adsorbent for removal of hexavalent chromium from aqueous solution
The result of isotherm and kinetics studies was in agreement with other studies conducted to examine the kinetics of Cr(VI) on activated carbon (Mullick et al 2017; TESHOME 2015; Tadesse et al 2015)
Summary
The generation rate of wastewater is increasing dramatically worldwide due to the increased consumption of water. Over 80% of the wastewater is discharged to the environment without prior treatment (UN-WWAP 2017). The problem is severe in developing countries because they discharge more than 90% of the wastewater into the environment without proper treatment. Cr(VI) adversely affects the kidney and liver and causes dermatitis, diarrhea, mouth ulcers, nosebleeds, low white blood cell counts— depressed immune defense systems, miscarriages, and a variety of cancers (Solomon 2008; Singh and Singh 2012). According to the Blacksmith Institute’s world worst pollution problems, chromium pollution adversely affects about 16 million people in 2015 globally (Black-Smith-Institute 2015). Chromium is known to bioaccumulate in algae, aquatic plants, invertebrates, and fish. Toxicological studies proved that hexavalent chromium, even at relatively low concentrations, can cause reduced growth and photosynthesis in algae and
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