Modification of Sargassum angustifolium by molybdate during a facile cultivation for high-rate phosphate removal from wastewater: structural characterization and adsorptive behavior.

Firozeh Saberzadeh Sarvestani,Hossein Esmaeili,Bahman Ramavandi

doi:10.1007/s13205-016-0570-z

Firozeh Saberzadeh Sarvestani, Hossein Esmaeili + Show 1 more

Open Access

https://doi.org/10.1007/s13205-016-0570-z

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Abstract

In this paper, a new and facile approach for molybdate loading in the brown algae of Sargassum angustifolium is introduced. The molybdate ions were entered into the algae body during a short cultivation to produce algae–Mo as a novel adsorbent for eliminating phosphate ions from synthetic and real wastewaters. Results of the surface analysis showed that molybdate loading onto the algae was successfully performed. Herein, basic variables, such as initial solution pH, adsorbent dosage, contact time, phosphate concentration, and temperature, were investigated in detail to assess the phosphate adsorption performance of algae–Mo. The pseudo-second-order kinetic model fitted our acquired experimental kinetic data most appropriately, in comparison to the use of a pseudo-first-order model. The Langmuir model appeared to fit the adsorption data more desirably than that of Freundlich and Dubnin–Radushkevich models, with a maximum phosphate adsorption capacity of 149.25 mg/g at 25 °C. The finding of the thermodynamic study revealed that the phosphate adsorption onto algae–Mo was spontaneous, feasible, and endothermic in nature. The study on Mo2+ ions leaching strongly suggested that the risk of Mo2+ leakage during phosphate adsorption was negligible at a wide pH range of 3–9. The adsorption efficiency attained was 53.4% at the sixth cycle of reusability. Two real wastewaters with different qualities were successfully treated by the algae–Mo, suggesting that the algae–Mo could be ordered for practical wastewater treatment.

Highlights

Phosphate (PO43−) is a basic material for many industries, including beverages, fertilizers, detergents, pharmaceuticals, paints, and corrosion inhibitors
Numerous adsorbent materials have been used for phosphate removal, such as sugarcane bagasse (Zhang et al 2011), soybean milk residues (Nguyen et al 2013), granular date stones (Ismail 2012), iron/zirconiumloaded okara (Nguyen et al 2014a), zirconium-loaded MUROMAC (Biswas et al 2008), and bayoxide-E33 (Lalley et al 2016) with the maximum adsorption capacity of 1.10– 131.77 mg/g
Surface analysis showed that algae–Mo particles had a BET multipoint surface area of 1.44 m2/g and a total pore volume of 0.0497 cm3/g

Summary

Introduction

Phosphate (PO43−) is a basic material for many industries, including beverages, fertilizers, detergents, pharmaceuticals, paints, and corrosion inhibitors. Excess amounts of wastewater phosphate discharged into water reservoirs, such as streams, rivers, and lakes, can cause algal bloom and eutrophic conditions. To control such adverse effects in water bodies and to maintain good effluent quality, removal of the excessive phosphate in wastewaters is required. This will ensure that the phosphate concentration in effluent from wastewater treatment plants, runoff, and subsurface drainage from agricultural land and urban areas, as well as domestic septic systems does not exceed 0.1 mg/L, a concentration above which eutrophication is likely (Johir et al 2015).

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