Application of Opuntia ficus-indica in bioremediation of wastewaters: a critical review

Heavy metal ion, pesticide and dye wastewaters cause severe ecological contamination with conventional treatment methods proving inadequate, unsuccessful or expensive to apply. Several biomaterials have recently been explored for the biosorption and biocoagulation-flocculation of pollutants .from wastewaters. In the past 10 years, there has been an extensive research output on the use of biological materials such as agricultural wastes, chitosan, Motinga Oleifera, Eichhomia crassipes. bapteria,/algae. Cactus plants etc. in environmental remediation. The present paper reviews the scattered iniof(nation about the green technology involving Opuntia ficus-indica derived biomaterials in wastewaf^n efecon- tamination. Its characterization, physicochemical compositions,its application in biosorptiorelaftd flocculation of dyes, pesticides and metallic species focussing on equilibrium, kinetics and thermodynamic properties are reviewed. The main results obtained in the depollution of a variety of contaminated wastewaters using cladodes, fruit pulp and peels mucilage and electrolytes show very high and promising pollutant maximum sorption capacities and removal percentages in the range -125.4,-1000 mg/g and 0.31-2251.56 mg/g for the biosorption of dyes and metallic species respectively and removal % ranges of 50-98.7%, 11-93.62% and 17-100% for turbidity, chemical oxygen demand and heavy metals respectively by coagulation-flocculation process. The biomaterials proved to be efficient in pollutant removal that there is need to explore the scaling up of the study from the laboratory scale to community pilot plants and eventually to industrial levels

Competitive adsorption of Pb2+, Cd2+ and Zn2+ ions onto Eichhornia crassipes in binary and ternary systems

A batch sorption technique was used to study the biosorption of Pb2+, Cd2+ and Zn2+ ions onto the vastly abundant water hyacinth weed, Eichhornia crassipes biomass in binary and ternary systems at a temperature of 30 C and pH 4.84. Mutual interference effects were probed using equilibrium adsorption capacity ratios, q0 e=qe, where the prime indicates the presence of one or two other metal ions. The combined action of the metals was found to be antagonistic, and the metal sorption followed the order Pb2+ Cd2+ Zn2+. The behaviour of competitive biosorption for Pb–Cd and Pb–Zn combinations were successfully described by the Langmuir Competitive Model (CLM), whilst the model showed poor fitting to the Cd–Zn data. In conclusion, Pb2+ ions could still be effectively removed from aqueous solution in the presence of both Cd2+ and Zn2+ ions, but removal of the Cd2+ and Zn2+ ions would be suppressed in the presence of Pb2+

Single and Binary sorption of lead(II) and zinc(II) ions onto Eichhornia Crassipes (water hyacinth) ash

Eichhornia crassipes ash was used for the removal of Pb(II) and Zn(II) ions from mono and binary systems. Batch equilibrium studies were carried out under optimum conditions and the results were analysed by the Langmuir and Freundlich adsorption isotherms for single metal systems and by Langmuir competitive model for binary metal systems. The equilibrium data fitted well to both mono sorption isotherm models with R2 ≥ 0.99. The ash had greater affinity for Pb(II) ions (qm = 50 mg g-1 and n = 1.05) than Zn(II) ions (qm = 16.67 mg g-1 and n = 1.04) in mono sorption systems. There existed competition between Pb(II) and Zn(II) ions during their simultaneous removal by the ash (R2 ≥ 0.97). The ash showed preference for Pb (II) ion sorption (qm* = 50 mg g-1 and qm*/qm = 1) than Zn(II) ions (qm* = -2.94 mg g-1 and qm*/ qm = -1.53) that was attributed to physicochemical properties of the cations. Pb (II) and Zn (II) ions can be significantly sorbed onto Eichhornia crassipes ash from single metal systems. However, in multi-metal systems, the removal of Zn (II) ions is inhibited by Pb (II)ions, while Pb(II) ions removal is not affected by the presence of Zn(II) ions

Afzelia quanzensis bark extract for green synthesis of silver nanoparticles and study of their antibacterial activity

In the present study, Afzelia quanzensis bark 8 extract was tested for the biosynthesis of silver nanopartiJHJcles (AgNPs). Based on UV-Vis spectrum analysis, the 10 characteristic absorption band was observed at 427 nm. 11 Furthermore, the size and shape of the nanoparticles ranged 12 from 10 to 80 nm and were spherical in shape as observed 13 through SEM analysis. In addition, the X-ray diffraction URBlanalvsis showed that the silver nanoparticles are crystalline 15 in nature and have a face-centred cubic structure. Based on 16 FTIR analysis, the presence of phytochemical functional 17 groups such as carboxyl (-C=0) and amine (N-H) in 18 Afzelia quanzensis bark extract further confirmed the 19 responsible reducing agents for nanoparticles formation. 20 Interestingly, the synthesized silver nanoparticles at 50 mg/ 21 L concentration showed significant antibacterial activity 22 against Escherichia coli and Staphylococcus aureus

Exploring the use of cactus Opuntia ficus indica in the biocoagulation–flocculation of Pb(II) ions from wastewater

Coagulation–flocculation processes play an important role in the treatment of water using inorganic and synthetic materials. Presently, cactus Opuntia ficus indica is explored as a cheap, abundant and eco-friendly bioflocculant of Pb(II) ions from aqueous solutions. The cactus powder was characterized by Fourier transform infrared spectrometer (FTIR), and the coagulation–flocculation process was optimized for pH, initial concentration of Pb(II) ions, particle size, dosage, ionic strength, contact time and temperature before its application to Mukuvisi River water. FTIR confirmed the involvement of –C–O–C–, –OH, –C=O, –N–H and –C–H groups of the polysaccharides, carboxylic acids and amino acids in the removal of Pb(II) ions. The variation of percentage removal and zeta potential with pH and flocculant dosage suggested the involvement of adsorption–charge neutralization and adsorption–bridging mechanisms in the coagulation–flocculation process. The process was optimum at pH 5, natural ionic strength, dosage of 8 mg/L, corresponding to zero zeta potential, with particle size <75 µm, at 35 °C for a floc settling time of 180 min. The coagulation–flocculation process was spontaneous and endothermic with a positive change in entropy of the system. Total heavy metal removal of 100 % (Pb), 85.74 % (Zn), 84.16 % (Cd) and 93.02 % (Cu) were achieved, under optimum conditions, when Opuntia ficus indica powder was used to remove metals from water sampled from Mukuvisi River, Harare, Zimbabwe. The cactus Opuntia ficus indica powder was found to be an efficient, eco-friendly flocculant that can effectively remediate Pb(II) ions from wastewaters

Kinetics and equilibrium studies on the biosorption of Cr(VI) by vigna subterranean (L.) verdc hull

The Vigna Subterranean (L.) Verdc hull’s (VSVH) potential to remove Cr(VI) ions from aqueous solutions was investigated. The biosorbent was characterised by FTIR, SEM-EDX and XRF before and after exposure to Cr(VI). The surface comprised of phenolic, carboxylate, sulphonate, carboxyl, ammines, silica, silanol, phosphite esters, alkyl and hydroxyl functional groups responsible for Cr(VI) removal. Batch experiments were carried out in erlenmeyer flasks to optimize pH, contact time, biosorbent dosage and initial concentration of Cr(VI) ions. Reutilization of biosorbent was investigated using predetermined and optimized 0.14 M H2SO4. The initial and residual total chromium concentrations were estimated by FAAS. The optimum pH, contact time and biosorbent dosage were found to be 2, 180 minutes and 3 g/L respectively. The data generated from the effect of contact time and initial Cr(VI) concentration was subjected to kinetics and isotherm modelling respectively. The kinetic data fitted the pseudo first order model (R 2 = 0.9334) and the sorption mechanism was diffusion controlled with both film and intra particle diffusion involved in the rate limiting step. The isotherm study confirmed favourable monolayer sorption best described by Langmuir model (R2 = 0.9986) with a very high monolayer sorption capacity of 232.5581 ± 0.9 mg/g. The Temkin model confirmed the endothermicity and weak ion-exchange nature of the Cr(VI)-biosorbent interactions that are important for biosorbent reuse. The biosorbent was recycled three times without significant loss of sorption-desorption capability. VSVH powder provides a renewable and reusable alternative for simple and effective Cr(VI) removal from wastewaters worth exploring for commercial-industrial application

Exploring the biosorption of Methylene Blue dye onto acid treated sugarcane bagasse

The potential of acid treated sugarcane bagasse (ATSB) to remove methylene blue from waste waters was explored. Surface characterization of the biomass before and after MB sorption was achieved using FTIR spectrophotometer. The ATSB had surface functional groups, SiO2 and C were performed under optimized pH, contact time, biosorbent dosage and varying MB initial concentrations. The Langmuir, Freundlich, Temkin, Dubinin equilibrium data generated from the effect of MB initial concentration. The equilibrium data fitted the isotherms in the order: Langmuir > Freundlich = Halsey > Dubinin 0.9957 to 0.9621. The Langmuir isotherm based separation factor, R intensity, n, (1/n < 1) indicated sorption favorability between MB and ATSB with the Langmuir sorption capacity of 64.9351 mg/g. The Fre comprised of both macropores and micropores. The energy of sorption, E R and Temkin isotherms respectively indicated that the biosorption nature. ATSB can be used to remove MB from waste waters. However there is need to explore the effects of metal ions, anions and other dyes on the removal of MB by ATSB

Fabrication of a sustainable maize stover-graft-methyl methacrylate biopolymer for remediation of methyl red contaminated wasters

In the present study, a sustainable maize stover-g-methyl methacrylate (MS-g-MMA) biopolymer was synthesized by free radical polymerization using benzoyl peroxide initiator and applied in the removal of methyl red dye from aqueous solutions. Monomer concentration, initiator concentration, temperature and reaction time were the synthesis independent variables. The prepared biopolymer was characterized by scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) and fourier transform infrared spectroscopy (FTIR). The effects of pH (2 − 11), contact time (5–300 min), initial concentration (5–50 mg/L), adsorbent dosage (0.2–2 g) and temperature (20–50 °C) were investigated through batch adsorption studies. The optimum conditions were determined to be pH 6, contact time 120 min, adsorbent dosage 0.2 g and initial concentration 5 mg·L− 1. The adsorption kinetic, isotherm and thermodynamic parameters were studied. The kinetic and isotherm data followed pseudo-second-order and Langmuir models, respectively. The maximum adsorption capacities of 13.58 and 23.47 mg/g were achieved for raw and modified maize stover, respectively. The adsorption process was endothermic, spontaneous and chemisorption. This study showed that MS-g-MMA could be applied as a potential biopolymer for the removal of methyl red from aqueous solutions

Electrodeposition of zinc oxide nanoparticles on multiwalled carbon nanotube-modified electrode for determination of caffeine in wastewater effluent

We report on the development of an electrochemical sensor based on electrodepositing zinc oxide on multiwalled carbon nanotube-modified glassy carbon electrode for the detection of caffeine in pharmaceutical wastewater effluents. The measurements were carried out using cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperometry and differential pulse voltammetry (DPV). DPV measurements showed a linear relationship between oxidation peak current and concentration of caffeine in 0.1 M HClO4 (pH 1.0) over the concentration range 0.00388–4.85 mg/L and a detection limit of 0.00194 mg/L. The diffusion coefficient and Langmuir adsorption constant for caffeine were calculated to be 3.25 × 10−6 cm2 s−1 and 1.10 × 103 M−1, respectively. The sensor showed satisfactory results when applied to the detection of caffeine in wastewater effluents