Cadmium Removal Percentage Research Articles

A synergistic integration of life cycle assessment and response surface methodology to optimize grape stalk waste-based biosorption for effective Cd(II) removal

In order to remove Cd(II) ions from aqueous solutions, this research suggests an in-depth study on a laboratory scale for the efficient and sustainable removal of Cd(II) in aqueous solution using wine industry grape stalk waste. The maximum biosorption capacity that was achieved was 84.74 mg/g for the Langmuir isotherm model. The kinetic studies revealed that the biosorption data were better explained by a pseudo-second order model. By using the response surface method with desirability functions, the optimal variables were determined for three optimization scenarios. The first optimization scenario yielded the highest percentage of cadmium removal, reaching 87.75%. The goal of that scenario was intended to obtain the maximum percentage of cadmium removal while minimizing the cost of the process. In this scenario, the greatest environmental impact was on the marine aquatic ecotoxicity (2.685 kg 1.4 DB eq.) with a power consumption of 27.05 W. Furthermore, the values for the input variables were an initial cadmium concentration of 0.6 mg/l, pH of 7.5, stirring time of 10 min, stirring speed of 100 rpm, a process temperature of 15 °C, and a dose of grape stalk of 0.50 g. The experimental and predicted findings agree. This suggests that grape stalk waste has potential applications as a biosorbent for the removal of Cd(II) ions from aqueous solution.

Enhancement of Cadmium Adsorption Capacities of Agricultural Residues and Industrial Fruit Byproducts by the Incorporation of Al2O3 Nanoparticles.

In this work, two types of residues (industrial fruit byproducts and agricultural wastes) were studies as promising adsorbents for cadmium uptake. Adsorption experiments using the evaluated biomasses (corn crops CC, palm bagasse PB, orange peels OP, and lemon peels LP) were conducted in batch mode by varying initial solution pH (2, 4, and 6) as well as the particle size (0.355, 0.5, and 1 mm). The optimum operating conditions were defined for further adsorption tests. The biomasses were chemically modified with alumina nanoparticles to evaluate the enhancement in adsorption capacities and how the nature of biomass contributes to successful incorporation of nanotechnology-based materials. The point of zero charges was ranged between 4 and 5 for all biomasses. Simultaneously, the Böehm titration method confirmed the presence of lactonic and carboxylic acid groups on the surfaces of the biomasses. Optimum operating conditions for batch cadmium adsorption experiments were observed at pH 6. Moreover, no significant changes were detected as a function of biomass size. For corn cob and lemon peels, removal percentages at 86 and 88% were reached using particle size = 0.5 mm. For palm bagasse and orange peels, the optimum parameters were 0.355 and 1 mm, respectively. Al2O3 nanoparticles with a crystal size of 58 ± 12 nm were obtained by applying the sol–gel methodology. A higher cadmium removal percentage was detected after using the biomasses modified with the Al2O3 nanoparticles, determining for the agricultural wastes an adsorption capacity of 91% (CC-Al2O3) and 92% (PB-Al2O3). In comparison, the industrial fruit byproducts exhibited a removal percentage of 93% (LP-Al2O3) and 96% (OP-Al2O3). The modification of industrial fruit byproducts (lemon peels and orange peels) showed increases in adsorption efficiencies around 12–6% after incorporating alumina nanoparticles, suggesting that this type of biomass is more suitable for adsorption property enhancement using nanomaterials.

Improvement of cadmium phytoremediation after soil inoculation with a cadmium-resistant Micrococcus sp.

Cadmium-resistant Micrococcus sp. TISTR2221, a plant growth-promoting bacterium, has stimulatory effects on the root lengths of Zea mays L. seedlings under toxic cadmium conditions compared to uninoculated seedlings. The performance of Micrococcus sp. TISTR2221 on promoting growth and cadmium accumulation in Z. mays L. was investigated in a pot experiment. The results indicated that Micrococcus sp. TISTR2221significantly promoted the root length, shoot length, and dry biomass of Z. mays L. transplanted in both uncontaminated and cadmium-contaminated soils. Micrococcus sp. TISTR2221 significantly increased cadmium accumulation in the roots and shoots of Z. mays L. compared to uninoculated plants. At the beginning of the planting period, cadmium accumulated mainly in the shoots. With a prolonged duration of cultivation, cadmium content increased in the roots. As expected, little cadmium was found in maize grains. Soil cadmium was significantly reduced with time, and the highest percentage of cadmium removal was found in the bacterial-inoculated Z. mays L. after transplantation for 6weeks. We conclude that Micrococcus sp. TISTR2221 is a potent bioaugmenting agent, facilitating cadmium phytoextraction in Z. mays L.

Bacterial-assisted cadmium phytoremediation by Ocimum gratissimum L. in polluted agricultural soil: a field trial experiment

A field study of cadmium phytoremediation by Ocimum gratissimum L. and the potential enhancement by two cadmium-resistant bacteria, Ralstonia sp. TISTR 2219 and Arthrobacter sp. TISTR 2220, were explored in a cadmium-polluted agricultural area. The results demonstrated the ability of one of the bacterial strains to promote cadmium accumulation in O. gratissimum L. planted in soil with cadmium concentrations till 65.2 mg kg−1. After transplantation in contaminated soil for 2 months, soil inoculation with Arthrobacter sp. enhanced cadmium accumulation in the roots, above-ground tissues, and whole plant of O. gratissimum L. by 1.2-fold, 1.4-fold, and 1.1-fold, respectively, compared with the untreated control. The presence of Arthrobacter sp. in soil facilitated cadmium phytoremediation in O. gratissimum L. similar to that of an EDTA application. Seeds of O. gratissimum L. grown in polluted soil contained undetectable to negligible concentrations of cadmium. Significant increases in the bioconcentration and translocation factors of O. gratissimum L. were observed in Arthrobacter sp.-inoculated plants at only 2 months post-transplant compared with the uninoculated control. The highest percentage of cadmium removal was found in soil used to cultivate EDTA-treated O. gratissimum L., followed by an Arthrobacter sp.-inoculated plant. Our findings suggest that the synergistic use of Arthrobacter sp. with O. gratissimum L., an essential oil-producing crop, could be a feasible economic and environmental option for the reclamation of cadmium-polluted areas.

Utilization of a natural ecosystem bio-waste; leaves of Arundo donax reed, as a raw material of low-cost eco-biosorbent for cadmium removal from aqueous phase

Arundo donax reed grows in a natural ecosystem in Wadi Shueib in Jordan and is also grown in constructed wetlands built for domestic wastewater treatment. The utilization of leaves of excessive A. donax reed as an ecosystem bio-waste for the removal of Cd2+ from aqueous solutions was investigated. Effects of pH (3.5 to 7.5), contact time (10 to 360min), adsorbent dose (2.5 and 5gl−1), and adsorbate concentration (5 to 50mgl−1) at an ionic strength of 0.01M NaNO3 on adsorption efficiency and capacity were studied in batch adsorption experiments. Cadmium removal percentage of 92% occurred in 20mgl−1 Cd solutions at pH 5.5 containing 5gl−1 powdered leaves of A. donax. Cadmium removal percentage increased to 97% with decreasing the adsorbent dose to 2.5gl−1. The adsorption process was relatively fast and equilibrium was attained at 120min contact time. The equilibrium adsorption capacity of A. donax leaves increased from 1.96 to 18.80mgg−1 with increasing initial Cd concentration from 5 to 50mgl−1. The kinetic process of Cd2+ adsorption onto leaves of A. donax obeyed the pseudo-second-order kinetic model (R2>0.9995) indicating that chemisorption is the rate-limiting step. Although Freundlich and Langmuir isotherm models described well the experimental data, equilibrium isotherm data were best described by Freundlich model (R2 0.990 and 0.978, respectively). The monolayer adsorption capacity was 27.9mgg−1. A. donax leaves can be potentially used as a raw material of low cost eco-biosorbent for treating Cd-contaminated water systems.

Modification of polyethersulfone using sericin and polyvinylpyrrolidone for cadmium ion removal by polyelectrolyte-enhanced ultrafiltration

The present study deals with the synthesis of polyethersulfone (PES)-based membrane using a biopolymer sericin and polyvinylpyrrolidone (PVP) by phase inversion process. The synthesized membranes were characterized for hydrophilicity, pure water permeability (PWP), membrane stability, and surface functional group analysis. The synthesized membranes were used to study the effective removal of cadmium ions using poly(diallyldimethylammoniumchloride) and polyethyleneimine (PEI) by polyelectrolyte-enhanced ultrafiltration. PVP-sericin-incorporated PES membrane resulted in the highest average pore radius (22 nm) and PWP (34.11 L m−2 h−1 bar−1). It also showed that higher antifouling resistance of 10 folds than neat PES membrane retained the higher flux rate. Overall, PES/sericin/PVP membrane has better characteristics, and maximum percentage of cadmium removal was obtained when added with PEI ligand.

Influence of Reduction Agent of SSI on its Cadmium Removal from Wastewater

Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by charcoal or hydrogen. The capability of cadmium removal by SSI was investigated in. It was suggested that the reaction of SSI reduced by hydrogen was higher than that reduced by charcoal, and the increasing rate of pH and cadmium removal in solution by SSI reduced by hydrogen was higher than that reduced by charcoal. Moreover, cadmium removal percentage by SSI reduced with hydrogen was much higher than that reduced by charcoal. When the original concentration of cadmium was 50mg/L, cadmium removal by SSI appeared to be the pseudo-first-order reaction because the reaction order was from 0.861 to 0.984. The apparent reaction rate constant of cadmium removal by SSI reduced with charcoal was 0.586 h-1. While hydrogen was utilized as reduction agent, the apparent reaction rate constant of cadmium removal was increased by 7.3 and 13.7 times.

Influence of pH on Cadmium Removal from Wastewater by SSI

Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. pH value in solution increased despite initial pH because a large amount of H+ was depleted along with erosion battery reaction of SSI. It was suggested that initial pH has significant influence on pH value in solution and cadmium removal percentage by SSI. When the initial pH maintained at 2.03, cadmium removal percentages were only 10.17% and 22.00%, respectively, in 10min and 30min. While the initial pH was adjusted to 3.00, cadmium removal percentage could be elevated to 73.10% and 95.46% in similar libration time. Cadmium removal by SSI appeared to be the first-order reaction. When the initial pH was maintained at 2.03, the apparent reaction rate constant of cadmium removal by SSI was only 0.434 and 1.027 h-1, while which could be elevated to 5.882 and 5.249 h-1 when the initial pH was adjusted to 3.00.

Use of Jordanian natural zeolite as sorbent for removal of cadmium from aqueous solutions

This study considers Jordanian zeolite as adsorbent for the removal of cadmium from aqueous solution. Zeolite collected from a geographic zone in Jordan valley was assesses for its ability to adsorb heavy metal after preliminary treatment. Kinetics and equilibrium of cadmium uptake by this new adsorbent were followed in this investigation. The experimental results showed that the adsorption of Cd2+ ions on zeolite sands was dependent on the pH and temperature. The uptake of cadmium ions increased with increasing pH, temperature and initial adsorbate concentration. Cadmium per unit adsorbent decreased with the increase in the amount of adsorbent used; while the percentage of cadmium removal increased with the increase in the amount of adsorbent. Addition of electrolyte, as NaCl, to zeolite-metal suspension decreased metal uptake by the zeolite.