Potential of Moringa Oleifera Seed as a Natural Adsorbent for Wastewater Treatment

The present study deals with the appropriateness of the coagulation process using natural coagulant Moringa oleifera seed. Natural coagulants are useful for the treatment of wastewater because of its sustainability, cost-effectiveness, non-toxicity and lesser quantity of sludge formation. M. oleifera seed having a chemical composition of polypeptides having 6 amino acids like arginine acid, methionine acid, glutamic acid, phenylalanine, threonine, and histidine. M. oleifera is also known as a cationic polyelectrolyte and having molecular weight 6,000 to16,000 Dalton. The main objective of research work is the application of the M. oleifera seed as a natural adsorbent to treat synthetic dairy wastewater. The effects of pH, agitation time, the dose of sorbent and efficacy of M. oleifera seeds kernel for turbidity removal was assessed. M. oleifera seed eliminates turbidity 95 % and colour 94 % using 0.22 gm pod powder, and 0.2 L of 1.0 g/L synthetic dairy wastewater. Naturally dried M. oleifera seeds remove turbidity 95 %, sundried seeds remove turbidity 52 % and oven-dried seeds 45 %. As naturally dried M. oleifera pod having more surface area for adsorption and inter-particulate bridging which extract the extra active ingredients. pH range between 5 and 8 is more suitable to degrade the turbidity and colour. It is concluded that in the presence of an aqueous soluble cationic coagulant protein has great potential to remove the turbidity and colour of wastewater. HIGHLIGHTS oleifera seed having a chemical composition of polypeptides having 6 amino acids like arginine acid, methionine acid, glutamic acid, phenylalanine, threonine, and histidine oleifera seeds consist of crude fiber, lignin, hemicellulose, and cellulose. It also contains amino functional groups (R-NH3), carboxyl group (C=O), and fiber carbonaceous. The functional group present in M. oleifera seeds is dissociated during the adsorption process at various pH oleifera has good property of coagulation-flocculation (C-F) The effectiveness of naturally dried seed kernel is more effective than other seed kernels GRAPHICAL ABSTRACT

Investigation on the use of aluminium rich sandy soil as natural adsorbent in the removal of lead from water

The feasibility of aluminium rich sandy soil collected from Jeram as natural adsorbent in removing lead (Pb) from water was investigated without any surface modification. The investigation on the effect of initial concentration, solution pH, and soil:solution ratio was carried out using response surface methodology. The adsorption efficiency was increased at higher pH and soil:solution ratio, as well as lower initial concentration, as a result of higher availability of adsorption sites and less adsorbate competition. The adsorption followed Langmuir isotherm and monolayer chemisorption with an adsorption capacity of 10.64 mg g−1. The process followed pseudo-second order kinetic model, with a rate constant of 0.011 g mg−1 min−1 at optimum adsorption pH of 4-5.

Remediation of Emerging Heavy Metals from Water Using Natural Adsorbent: Adsorption Performance and Mechanistic Insights

The presence of potentially toxic metals in water causes a strong impact on environment and human health. In this study, activated biochar was produced by using chemical oxidation method from wheat straw as natural adsorbent and was employed for heavy metals competitive remediation. The morphology, structure, and chemical properties of biochar before and after adsorption were characterized by FTIR, XRD, SEM and EDX mapping techniques. The competitive adsorption efficiency of adsorbent for divalent cadmium (Cd) and lead (Pb) from contaminated water was investigated by using wide range of several initial metal concentration, contact time and pH. Maximum adsorption of Cd(II) and Pb(II) was found in the pH range of 6–8. The adsorption capacity for Cd(II) and Pb(II) was 8.85 and 9.03 mg/g, respectively. Thermodynamics parameters and kinetic models were applied to adsorption data. The isotherm data followed Langmuir model, corresponding to monolayer adsorption of the two ions in the contaminated water. The kinetic data followed the pseudo 2nd order kinetics model, which authenticates the chemisorption nature. The thermodynamic study indicated that Cd adsorption is a spontaneous exothermic process while Pb adsorption is an endothermic process. Mineral precipitation, surface complexation, and cation-π interactions are the major remediation strategies for Cd(II) and Pb(II).

Investigation of Seeds and Peels of Citrullus colocynthis as Efficient Natural Adsorbent for Methylene Blue Dye

Natural adsorbents as low-cost materials have been proved efficient for water remediation and have significant capacity for the removal of certain chemicals from wastewater. The present investigation aimed to use Citrullus colocynthis seeds (CCSs) and peels (CCPs) as an efficient natural adsorbent for methylene blue (MB) dye in an aqueous solution. The examined biosorbents were characterized using surface area analyzer (BET), scanning electron microscope (SEM), thermogravimetric analyzer (TGA) and Fourier transform infra-red (FT-IR) spectroscopy. Batch adsorption experiments were conducted to optimize the main factors influencing the biosorption process. The equilibrium data for the adsorption of MB by CCSs were best described by the Langmuir isotherm followed by the Freundlich adsorption isotherms, while the equilibrium data for MB adsorption by CCPs were well fitted by the Langmuir isotherm followed by the Temkin isotherm. Under optimum conditions, the maximum biosorption capacity and removal efficiency were 18.832 mg g−1 and 98.00% for MB-CCSs and 4.480 mg g−1 and 91.43% for MB-CCPs. Kinetic studies revealed that MB adsorption onto CCSs obeys pseudo-first order kinetic model (K1 = 0.0274 min−1), while MB adsorption onto CCPs follows the pseudo-second order kinetic model (K2 = 0.0177 g mg−1 min−1). Thermodynamic studies revealed that the MB biosorption by CCSs was endothermic and a spontaneous process in nature associated with a rise in randomness, but the MB adsorption by CCPs was exothermic and a spontaneous process only at room temperature with a decline in disorder. Based on the obtained results, CCSs and CCPSs can be utilized as efficient, natural biosorbents, and CCSs is promising since it showed the highest removal percentage and adsorption capacity of MB dye.