Abstract
Biosorption using natural waste has emerged as a potential and promising strategy for removal of toxic dyes from wastewaters in comparison to conventional ones. Herein, the Codium decorticatum alga (CDA) was biologically identified and used as a biosorbent for anionic and cationic dyes from aqueous solutions. SEM analysis showed a rough surface with an irregular edge and shape while hydroxyl, amine, sulfur and carboxyl functional groups were identified using FTIR analysis. TGA/DTG confirmed the stability of CDA and the adsorption process. Batch studies were conducted to investigate the effect of operational factors such as initial pH, biosorbent dosage, temperature, initial concentration, and solid/liquid contact time on the biosorption of crystal violet (CV) and Congo red (CR) dyes. For both CV and CR dyes, the biosorption kinetics was accurately described by the pseudo-second-order model and the Langmuir isotherm was found to be best fitted for equilibrium data. Maximum uptake capacities have attained up to 278.46 mg/g for CV and 191.01 mg/g for CR. The CV and CR dye biosorption mechanism was ultimately manifested through the electrostatic interactions. The regeneration study showed that the CDA presents excellent reuse performance up to four consecutive cycles. The process optimization was performed using the response surface methodology based on Box–Behnken design (RSM-BDD). Accordingly, the optimum predicted removal efficiencies using RSM-BBD for CV and CR were obtained, respectively, at 96.9 and 89.8% using a CDA dose of 1.5 g/L, dye concentration of 20 mg/L, pH of 10 for CV, and pH of 4 for CR. Overall, CDA behaves as an efficient, recyclable, cheap, and eco-friendly adsorbent for cleaning-up of dyed effluents.
Highlights
The overwhelming discharge into wastewater, as well as clean water, is expected to provoke diseases and perturbations of the ecosystem from domestic and industrial wastes.[1,2] Since many researchers around the world have confirmed that heavy metals and dyes are frequently released into the aquatic environment.[3]
The medium pH, as it is well known, plays an indispensable role in the biosorption process; correspondingly, we have evaluated the influence of this factor on crystal violet (CV) and Congo red (CR) dye biosorption onto the Codium decorticatum alga (CDA) biosorbent by varying the pH from 2.0 to 11.8, using an optimum sorbent dose of 1 g/L for 120 min at ambient temperature
Fourier transform infrared (FTIR) analysis exhibited that the chemical structure of isolated CDA contains several functional groups such as hydroxyl, amine, sulfur, and carboxyl groups
Summary
The overwhelming discharge into wastewater, as well as clean water, is expected to provoke diseases and perturbations of the ecosystem (flora and fauna) from domestic and industrial wastes.[1,2] Since many researchers around the world have confirmed that heavy metals and dyes are frequently released into the aquatic environment.[3]. Dyes are mutagenic and carcinogenic agents and attack the whole food chain.[4] dyes could be released into common wastewater and affect the growth of plants and germination by irrigation agriculture.[5,6] Several techniques, such as ultrafiltration,[7] coagulation,[8] photocatalysis,[9] osmosis,[10] and adsorption,[11] were used to get rid of dyes or reduce their toxicity. In this context, the development of low-cost and efficient methods to remove the contaminants from water is required. Several species, such as Ulva lactuca,[20] Caulerpa stapeliiformis,[21] Chlorella vulgaris,[22] Systoceira stricta,[23] Spirogyra,[24] are used as biosorbents for efficient elimination of colored compounds from drinking and contaminated waters
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