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The current investigation was designed to remove halosulfuron methyl from aqueous media by means of neem seed powder (NSP) in batch modes. Characterizations of NSP were carried out by using EDX, SEM, FTIR, point of zero charge and surface analysis. Optimum operation conditions were scrutinized by studying the influence of different factors like solution pH, dose of NSP, contact time, initial halosulfuron methyl concentration and temperature. Result indicates the dependency of the removal of halosulfuron methyl on solution pH and maximal removal (54%) was achieved in acidic medium (i.e. pH 3.0). To identify the chemical surface of NSP, point of zero charge of NSP was determined and was found to be 6.5 which imply that the surface of NSP is positively charged below pH 6.6 and favored the anionic sorption. Kinetics of halosulfuron methyl were demonstrated well by pseudo second order due to highest R2 (0.99) owing to the nearness between experimental and calculated sorption capacities. Isotherm results imply that Langmuir was found to the principal model to explain the removal of halosulfuron methyl and maximum monolayer sorption capacity was determined to be 200 mg g−1. Thermodynamic parameters like ΔH°, ΔG° and ΔS° were calculated from van’t Hoff plot and were found negative which suggest that removal of halosulfuron methyl is exothermic and spontaneous at low temperature. These outcomes insinuate that neem seed power may be a valuable, inexpensive and ecofriendly biosorbent for the removal of pesticides.

Fe3O4 known as magnetite is one of the oxides of iron which plays a major role in various fields of sciences. Fe3O4 was synthesized by precipitation method using NH3.H2O, FeCl2.4H2O and FeCl3.6H2O as precursor materials. For synthesis of 5% Ag-Fe3O4, the green synthetic method was used for immobilization of Ag nanoparticles on Fe3O4 using leaves extract of Calotropis gigantea plant. The synthesized Fe3O4 and 5% Ag-Fe3O4 were employed as catalyst in degradation of methylene blue. The photo catalytic activity of Fe3O4 was remarkably enhanced by doping of Fe3O4 with Ag nanoparticles. Advanced instrumental techniques including XRD, EDX, TGA and SEM were used for characterization of synthesized particles. The immobilization of Ag on Fe3O4 enhanced the photo degradation of methylene blue from 40 to 72% at 40 °C which confirms that 5% Ag-Fe3O4 is an active catalyst for treatment of dye contaminated water. Ag-Fe3O4 exhibited almost same catalytic activity in two successive cycles. Bull. Chem. Soc. Ethiop. 2020, 34(1), 123-134. DOI: https://dx.doi.org/10.4314/bcse.v34i1.11

Visible light induced photo catalytic degradation of dyes is an inviting approach in wastewater treatment techniques. In this study, silver loaded alumina was synthesized by immobilization of Ag nanoparticles on Al2O3 by facile green method with Azadirachta indica leaves extract and characterized by different advanced techniques. The prepared Ag-Al2O3 particles were tested as photo catalyst on degradation of methylene blue under visible irradiation. Ag-Al2O3 showed improved photo catalytic performance on photo degradation of methylene blue. The deposition of Ag enhanced the photo catalytic activity of Al2O3 from 35 to 95% degradation of methylene blue. Effect of various parameters on catalytic activity were investigated. Curve Expert computer program was used for kinetics analyses of the data according to Langmuir–Hinshelwood and Eley–Rideal mechanism. A 100 mg L−1 solution (50 mL) completely degraded in 120 min of reaction duration at 50 °C over 0.1 g of 3% Ag-Al2O3 as catalyst. 0.01, 0.06 and 0.08 min−1 were calculated as average rate constants at 30, 40 and 50 °C respectively. 25.7 kJ mol−1 was calculated as average activation energy.

Green manufacturing of catalysts enables sustainable advanced oxidation processes and water treatment processes for removing trace contaminants such as pesticides. An environmentally friendly biosynthesis process produced high-surface-area CuO and NiO nanocatalysts using phytochemicals in the Capparis decidua leaf extract, which served as a reductant and influenced catalyst shape. Capparis decidua is a bushy shrub, widely distributed in dry and arid regions of Africa, Pakistan, India, Egypt, Jordan, Sudan, Saudi Arabia. The synthesized CuO and NiO nanoparticles were characterized by UV-vis spectroscopy (UV-vis), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) and thermo-gravimetric analysis/differential thermal analysis (TGA/DTA). The produced nanoparticles were spherical and flower-like in shape and have a characteristic face-centered cubic structure of CuO and NiO. Biosynthesized catalysts were photoactive and degraded recalcitrant pesticide Lambda-cyhalothrin (L-CHT). Photocatalytic degradation of L-CHT was affected by the initial L-CHT concentration, solution pH levels between 5 and 9, and photocatalyst concentration. The L-CHT removal percentage attained by CuO photocatalyst (~99%) was higher than for NiO photocatalyst (~89%). The degradation of L-CHT follows a pseudo-first-order kinetic model, and the apparent rate constant (kapp) decreased from 0.033 min−1 for CuO to 0.0084 min−1 for NiO photocatalyst. The novel flower-shaped nanoparticles demonstrated high stability in water and recyclability for removing L-CHT pesticide contamination in water.

The presence of heavy metals in water causes serious problems and their treatment before incorporating into the water body is a challenge for researchers. The present study was conducted to compare the sorption study of Ni (II) using silica gel, amberlite IR-120 and sawdust of mulberry wood in batch system under the influence of pH, initial Ni (II) concentration and contact time. It was observed that sorption process was depending upon pH and maximum sorption was achieved at pH 7.0. Kinetic data were well fitted into pseudo-second order kinetic model due to high R2 values and closeness of experimental sorption capacity and calculated sorption capacity of pseudo-second order. Isotherms study showed that Langmuir is one of the most suitable choices to explain sorption data due to high R2 values. The monolayer sorption capacities of silica gel, amberlite IR-120 and sawdust were found to be 33.33, 25.19, and 33.67 mg g−1, respectively. Desorption study revealed that NaCl is one of the most appropriate desorbent. It may be concluded from this study that sawdust is a suitable sorbent due to low cost, abundant availability and recycling of the materials for further study.

The plants assisted green synthesis of nanoparticles have drawn a momentous importance worldwide. NiO is one the metal oxides researched comprehensively for decades and still has dominance in the field of photo-catalysis. In present study NiO and Ag–NiO were successfully prepared by a simple and environmentally friendly method using nickel nitrate, silver nitrate and leaves extract of Azadirachta indica L. plant as precursor materials. The prepared materials were characterized by XRD, SEM and TGA. Then the photo-catalytic efficiency of NiO and Ag–NiO were evaluated by aqueous phase photo-degradation of rhodamine B as a model pollutant under ultraviolet irradiations. About 40% and 96% of 200 mg/L (50 mL) degraded in 120 min at 40 °C over NiO and Ag–NiO as photo-catalyst respectively. The apparent rate constants were determined as 0.0109, 0.0165, 0.0175 and 0.0190 per min at 30, 40, 50 and 60 °C respectively. 14.6 kJ/mol was calculated as activation energy of reaction.

The present study was carried out to know the sorption mechanism of Pb (II) and Ni (II) in aqueous solution using pea peels under the influence of sorbent dose, pH, temperature, initial metal ion concentration and contact time. SEM and FTIR were used for characterization of pea peels. The study showed that solution pH affects sorption process and the optimum pH for Pb (II) was 6.0 while for that of Ni (II) was 7.0. Pseudo-second order kinetic model was found to be the most suitable one to explain the kinetic data not only due to high value of R2 (>0.99) but also due to the closeness of the experimental sorption capacity values to that of calculated sorption capacity values of pseudo second order kinetic model. It can be seen from the results that Freundlich isotherm explains well the equilibrium data (R2>0.99). Sorption capacity of pea peels was 140.84 and 32.36 for Pb (II) and Ni (II) mg g-1 respectively. The positive value of ΔH° and negative values of ΔG° suggest that sorption of Pb (II) and Ni (II) onto pea peels is an endothermic and spontaneous process respectively.

Gamma and UV radiation alone and in the presence of oxidant (H2O2) were employed for the degradation of reactive yellow 145 dye. The observed degradation was 82.73 and 77.93% under UV radiation, while 100 and 94.84% using gamma ray treatment for 50 and 100 mg/L drug initial concentrations along with H2O2, respectively. The reduction in COD was noted as 73 and 60% for 50 and 100 mg/L dye initial concentrations using gamma/H2O2 combined process, respectively. The pH was reduced significantly when the samples were treated with gamma/H2O2. The removal efficiency (G-value), dose constant (k), D0.50, D0.90 and D0.99 of gamma-ray treated samples were also evaluated. The cytotoxicity and mutagenicity were measured, which reduced significantly in response of radiation treatment. The 44.45 and 55.56% decrease in cytotoxicity was shown by the Allium cepa, whereas 77.45 and 80.41% in case of hemolytic while 83.75 and 88.65% reduction in cytotoxicity was noted by the shrimp assay using UV/H2O2 and gamma/H2O2 treatments, respectively. The mutagenicity of dye solutions was reduced to 78.25 and 83.13% (in case of TA98), while 82.53 and 85.32% (in case of TA100) using UV/H2O2 and gamma/H2O2 processes, respectively. Results suggested that AOP can efficiently be used to degrade and detoxify the textile wastewater.

This study focuses on synthesis of nickel oxide catalyst and exploration of its catalytic activities for degradation of methyl orange in aqueous medium. Nickel oxide was prepared sole-gel method using nickel nitrate haxahydrate and citric acid as precursor materials. X-ray diffractometry and scanning electron microscopy were used for characterization of prepared nickel oxide particles. The prepared particles were used as the catalysts for the degradation of Methyl Orange in aqueous medium. The effects of different parameters on degradation of methyl orange were investigated. The degradation of methyl orange followed the Eley-Rideal (E-R) mechanism. The apparent activation energies for degradation of methyl orange determined was found as 36.4 kJ/mol.

This study was focused on the sorption of chlorpyrifos from aqueous media utilizing synthesized zinc oxide nanoparticles impregnated Pea peels (ZnONPs-IPPs) in batch mode under the impact of pH of solution, dosage of sorbent, time of contact, temperature and initial pesticide concentration. The prepared composite was characterized by SEM, EDX, Surface area pore size analyzer and FTIR before and after sorption of chlorpyrifos. It was observed that the sorption of chlorpyrifos depends upon pH and maximal sorption (56%) was occurred at pH 2. The data of sorption process were fitted into Freundlich, Langmuir, Temkin and Dubinin–Radushkevich (D–R) isotherm models and the results indicate that Temkin isotherm is a suitable choice to describe the data owing to higher R2 value (0.99). Monolayer sorption capacity of ZnONPs-IPPs for chlorpyrifos of the Langmuir isotherm was found to be 47.846 mg g−1. Kinetics of sorption were described by fitting data into pseudo-1st-order, pseudo-2nd-order, Elovich, intraparticle and liquid film diffusion models and the results showed that pseudo-2nd order interprets the data well owing to the higher R2 (0.99) well as the close agreement between the calculated and experimental sorption capacity. Thermodynamic parameters ( Δ G ∘ is negative and Δ H ∘ is positive) imply that sorption process of chlorpyrifos utilizing ZnONPs-IPPs is spontaneous and endothermic in nature. The prepared composite is an economical and eco-friendly biomass and may be efficiently used for the removal of other pollutants.

This study explores the lab prepared nickel hydroxide catalyzed oxidative degradation of Methylene Blue (MB) in aqueous medium using batch reactor. Nickel hydroxide was prepared by reaction of sodium hypochlorite, sodium hydroxide and nickel sulphate hexahydrate in distilled water. The catalytic oxidative degradation of Methylene Blue was explored in terms of various parameters like effect of time, hydrogen peroxide, temperature, initial concentration of dye, catalyst dosage and effect of speed of agitation on degradation of Methylene Blue. Experimental data was subjected to kinetics analysis using Curve Expert software. Degradation reaction was taking place according to Langmuir-Hinshelwood mechanism. According to this mechanism the reactants adsorb at the surface of catalyst in first step followed by chemical reaction between adsorbed reactants in second step. Catalyst was heterogeneous in nature which was separated by simple filtration easily.

A low cost and environment-friendly agriculture waste material, orange peel, was investigated for the removal and accumulation of Pb(II) from water and wastewater. Orange peel treated with acid (AOP) as well as converted into carbon (COP) and the effect of various parameters on biosorption of Pb(II) on AOP and COP was studied. The biosorption of Pb(II) was found to be pH dependant in both cases and maximum biosorption of Pb(II) (100 %) on AOP was achieved at pH 6 and 60 min shaking time while using COP the maximum biosorption (100 %) was obtained at pH 5.5 and 80 min contact time. The monolayer biosorption capacities of AOP and COP were found to be 1 040 mg g−1 and 993 mg g−1 using Langmuir isotherm at room temperature respectively. Similarly Freundlich empirical constants, KF and n obtained for Pb(II) on AOP and on COP were 0.453 L g−1, 1.90 and 0.334 L g−1, 2.51 respectively. For the kinetic study of biosorption of Pb(II) on AOP and COP pseudo-first-order and pseudo-second-order intraparticle d...

An adsorption study of Rhodamine B (RB) dye from aqueous solutions was carried out using walnut shells pretreated by different methods. In addition to the effects of the pretreatment, the effects of various parameters like pH, adsorbent dose, contact time, initial dye concentration and temperature on the adsorption of RB was studied. The adsorption process was highly pH dependent and a maximum adsorption was achieved at pH 3.0. The best fit for the rates of dye adsorption was a pseudo-second-order kinetic model with good correlation coefficients (R2>0.99). Langmuir isotherms were used to determine that the maximum loading capacity of the different walnut shells and the RB capacities ranged from 1.451–2.292 mg·g−1. The dye adsorption was also evaluated thermodynamically. Positive standard enthalpy (ΔH°) values were obtained indicating that the RB adsorption process is endothermic as well as ΔG° and ΔS° values showed that adsorption process is spontaneous with an increased randomness at the solid-liquid interface. Desorption studies were carried out to explore the feasibility of regenerating the used walnut shells and it was found that 97.71%–99.17% of the retained RB was recovered with 0.1 mol·L−1 NaOH solution. The walnut shells were also successfully used to remove RB from industrial effluents.

The efficiency of indigenous functionalized sorbent (sawdust functionalized with polyaniline) was compared with synthetic functionalized sorbents (Dowex functionalized with 8-hydroxyquinoline (Dowex-8HQ) and α-nitroso-β-naphthol (Dowex-αNβN)) for preconcentration and determination of Cu (II) from aqueous samples. The synthetic functionalized sorbents and indigenous functionalized sorbent were characterized using FTIR. Different parameters like pH, equilibration time and sample volume were investigated for maximum sorption of Cu (II). Isotherm studies showed that the sorption data fitted well into Langmuir isotherm for the sawdust functionalized with polyaniline. Freundlich isotherm was followed for Dowex-8HQ and Dowex-αNβN. Four types of kinetic equations were applied to the data, and it was observed that sorption of Cu (II) followed second-order kinetics. Thermodynamically, the sorption of Cu (II) on these three sorbents was found to be exothermic and spontaneous. For maximum recovery of Cu (II) from loaded sorbents, different parameters like shaking time, eluent type, concentration and volume were investigated, and 89% Cu (II) was recovered from loaded sawdust functionalized with polyaniline and Dowex-8HQ. The interference studies showed the selectivity of sawdust functionalized with polyaniline for Cu (II) in comparison to synthetic functionalized sorbents. Thus, Cu (II) can be easily removed from aqueous samples in the presence of foreign ions.

Synthetic resin Dowex 1X8 was functionalized with α-Nitroso β-Naphthol (Dowex-αNβN) and with 8-Hydroxy Quinoline (Dowex-8HQ) to form chelating resin. The resultant chelating resins were characterized using scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The efficiency of these resins for the removal/preconcentration of Pb (II) from aqueous samples was evaluated. Optimum conditions of pH, time of equilibrium, and sample volume were investigated for maximum retention of Pb (II) from aqueous solutions. At optimum conditions, 100% adsorption was observed for the functionalized resins. Both Freundlich and Langmuir isotherms were applied to the adsorption data and it was observed that data fits well to Langmuir isotherm. Various parameters such as shaking time, type, and concentration of eluents were investigated for the recovery of Pb (II) from the chelating resins. For Dowex-αNβN and Dowex-8HQ, 100% recovery with a preconcentration fac...

In the present study sawdust, an inexpensive material, obtained from mulberry wood has been studied after treatment with hydrochloric acid as biosorbent for cadmium removal using batch experiments. The effect of different parameters on biosorption process, such as contact time with shaking and without shaking, pH of the solution, and initial concentration of Cd(II) ions were studied. The biosorption of Cd(II) ions was found to be pH dependent and maximum biosorption was achieved at pH 6 after 30 min shaking. The maximum biosorption capacity of CTSD obtained from Langmuir isotherm was 403.73 (mg g−1) for Cd(II) ions. The Langmuir isotherm showed monolayer biosorption process of Cd(II) ions on the surface of CTSD. The empirical constants of Freundlich isotherm KF and n obtained for Cd(II) ions were 0.334 (L g−1) and 4.83 respectively. The data shows that the pseudo-second-order model (r2 = 0.9887) was the best choice among the kinetic models studied for description of biosorption of Cd(II) ions on CTSD. The...