A comparative study on different metal loaded soybean milk by-product ‘okara’ for biosorption of phosphorus from aqueous solution

Abstract

Cationization of agricultural by-products using metal salts is widely used to activate their phosphorous capture ability. This study developed three kinds of new metal loaded soybean milk by-product 'okara' for phosphorus biosorption. A comparative study among these biosorbents was carried out with respect to their performances in terms of affinity, stability and reusability. Zirconium loaded okara (ZLO) was found to have the highest affinity towards PO(4)(3-) anions (47.88 mg/g), followed by iron/zirconium loaded okara--IZLO (40.96 mg/g) and iron loaded okara--ILO (16.39 mg/g). ZLO was successfully desorbed with 0.2M NaOH and activated with 0.1 HCl prior to the next cycle. After five consecutive cycles, the efficiency of both adsorption and desorption of ZLO remained about 85% whilst no Zr(IV) leakage was observed. Conversely, IZLO and ILO suffered from vital short comings such as high metal release and/or sharp reduction in PO4(3-) sequestering capability after multi operation cycles.

Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

“…In the earlier batch adsorption tests, the dilute alkaline solution (0.2 M NaOH) was proven to be the best desorption solution (Nguyen et al, 2014b). In the present study, 0.2 M NaOH was employed for eluting phosphorus from saturated ZLO column.…”

“…0.2 M NaOH was chosen as desorption solution while 0.1 M HCl was used for regeneration since these solutions were proven to be effective in the previous batch experiments (Nguyen et al, 2014b). Prior to desorption, phosphorus loaded ZLO was rinsed with 300 mL distilled water at the flow rate of 12 mL/min to remove residual phosphorus.…”

“…Metal loading provides the bio-materials with positively charged metal ions, which are suitable for retention of negatively charged anions, such as phosphate (Mallampati and Valiyaveettil, 2013). Zirconium was found to be an excellent loading metal in many studies performed by Biswas (2008); Mallampati and Valiyaveettil (2013); Nguyen et al, 2014b;Ohura et al (2011), etc. However, the high-cost remains a challenge, limiting the use of zirconium compounds for this purpose (Nguyen et al, 2014c;Ren et al, 2012).…”

Removal of As(V) from wastewater by chemically modified biomass

“…Adsorption is widely regarded as one of the most promising technologies because it is costeffective, little by-product, and simple operation. Biosorption has gained important credibility in recent years because of its eco-friendly nature, excellent performance, and low cost domestic technique for remediation heavily metal contaminated wastewater [12][13][14]. Cell wall of microorganisms, consisting abound polysaccharides, proteins and lipids, offers many functional groups (such as carboxylate, hydroxyl, thiol, sulfonate, phosphate, amino and imidazole groups) for the binding of metal ions [15].…”

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

“…Although chemical and biological methods are most commonly used for phosphate removal, adsorption processes have attracted increasing attention, with the primary benefits of being effective, best suited for low levels of phosphate, and favorable to phosphate recovery (Nguyen et al 2014a). So far, 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/zirconium-loaded 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.…”