Removal of reactive dye from aqueous solution using coagulation–flocculation coupled with adsorption on papaya leaf

Abstract

Attempts were made to investigate the effectiveness of a combined process of coagulation-flocculation and adsorption for the removal of reactive dye (Reactive Red 3BS) from aqueous solution. The effluent obtained from the coagulation-flocculation process was the raw solution for the second step of the coupling process, i.e. adsorption. The coagulation-flocculation process and the adsorption method were also studied individually. The optimum pH and the optimum dosages of alum and calcium oxide for the coagulation-flocculation process were determined. Aluminium sulphate (alum), calcium oxide and papaya leaf were used as the coagulant, coagulant aid and adsorbent, respectively. Complete dye removal from raw solution having a concentration of 100 mg L -1 could be achieved by using 300 mg L -1 of alum, 80 mg L -1 of calcium oxide and 0.20 g of papaya leaf adsorbent. Adsorption tests showed that papaya leaf could be used as a potential adsorbent for the removal of Reactive Red 3BS from aqueous solution. The maximum sorption capacities of papaya leaf in the case of sorption from pretreated solution and pure solution were 50.23 mg g -1 and 21 mg g -1 , respectively. The combined coagulation-flocculation/adsorption process may be a useful treatment technique for wastewater contaminated with reactive dye.

Phosphoric Acid Activated Carbon from Melia azedarach Waste Sawdust for Adsorptive Removal of Reactive Orange 16: Equilibrium Modelling and Thermodynamic Analysis

“…Currently, conventional technologies being adopted for the treatment of reactive dyes include photocatalytic degradation [ 7 ], enzymatic action [ 8 ], chemical coagulation/flocculation [ 9 ], ion exchange [ 10 ] and membrane separation [ 11 ], etc. At an industrial scale these conventional treatment processes have certain limitations: e.g., phase, shape, band gap, light source, structure, reactor design and catalyst recovery [ 12 ], the temperature specificity and alkaline conditions of laccase enzyme [ 13 ], residual sludge generation during chemical coagulation [ 14 ], slow pore diffusion, low accessible flow rates, high pressure drop and flow channeling in ion exchange [ 15 ], and chemical incompatibility in membrane separation [ 16 ], etc.…”

Natural-based coagulants/flocculants as sustainable market-valued products for industrial wastewater treatment: a review of recent developments

“…The coagulation/flocculation process is widely employed for industrial wastewater treatment to remove colloidal particles, dyes, heavy metals, and organic matter due to its ease of use, low cost, and upgradeability. 25,26 This process involves the addition of coagulants/flocculants, which can be chemical or natural materials that destabilize and aggregate the suspended particles and colloids in the wastewater. 27 Coagulants, such as aluminium sulfate, ferric chloride, and polyaluminum chloride, work by neutralizing the charge on the particles, while flocculants, such as polyacrylamide and chitosan, bind the destabilized particles together to form larger, denser flocs that can be easily separated from the wastewater.…”