Plating Effluent Research Articles

Reduction of hexavalent chrome from artificial effluent of chrome: Batch electrocoagulation method [Reducción del cromo hexavalente de efluente artificial de cromado: Método de electrocoagulación por lotes

The present research evaluated treatment time, electrode area / effluent volume ratio, on the% reduction of hexavalent chromium in artificial chrome plating effluents, was evaluated by the batch electrocoagulation method; Method for which A-36 steel anodes and cathodes of (5.0 x 5.0 x 0.2) cm were used. The number of electrodes and the separation between them was varied in order to vary the ratio of electrode area / effluent volume and; for a batch type electrocoagulation reactor in which 27 tests were carried out; keeping the volume of effluent treated constant. From the results obtained, it was determined that the increase in the electrocoagulation time and the electrode area / effluent volume ratio influence the percentage of hexavalent chromium reduction of the artificial chromium plating, as supported by ANOVA and test F; the maximum reduction percentage achieved was 91.65%, with respect to the initial concentration (20 mg/L), for a test time of 60 minutes and a ratio of electrode area / effluent volume of 0.912 m2/L.

Electron utilization efficiency of ZVI core activating PMS enhanced by C-N/g-C3N4 shell

Removal of complexation metal from plating effluents is always a problem. In this work, a core-shell structure zero-valent iron@nitrogen/graphite carbon nitride doped carbon (ZVI@C-N/g-C3N4) composite was prepared and used to activate peroxymonsulfate (PMS) to treat complexation nickel simulated wastewater. Compared with ZVI, ZVI@C-N/g-C3N4 significantly enhanced the efficiency and repeatability of PMS activation. For 45 min treatment, the removal efficiency of 50 ppm Ni-EDTA and Ni-citrate simulated wastewater reached 95.8 % and 100 %, respectively. The excellent performance of ZVI@C-N/g-C3N4 is attributed to that the amino groups of nitrogen in C-N/g-C3N4 shell can regulate the transmission rate of electrons released from ZVI core by adjusting the transmission rate of H+, so as to improve the electron utilization efficiency of PMS activation.

<strong>Bioremediation of hexavalent chromium from electroplating effluents by wild and mutant strains of <em>Bacillus amyloliquifaciens</em></strong>

Chromium, a heavy metal, is a major xenobiotic element found in electroplating effluents. It is a recalcitrant of concern as it is highly toxic and carcinogenic. It exists as Cr (VI) which is highly soluble and bioavailable. Various conventional treatment technologies like adsorption, ion exchange, filtration, reverse osmosis and electrodialysis have been used but they generate lot of sludge and residue. Hence, there is a need for an economical, faster and ecofriendly means of remediation for which bioremediation is preferred. In this study we attempted chromium removal by employing improved indigenous isolate Bacillus amyloliquifaciens sourced and identified from a previous study from chrome plating effluent collected from Peenya industrial area, Bengaluru, India. Strain improvement was achieved using physical mutagen (UV radiation) and chemical mutagens (ethidium bromide, ethyl methane sulphonate and acrylamide). A comparative study was carried out to screen the chromium remediation potential of wild type and mutants in chromium spiked sample and the electroplating effluent. The mutant generated using acrylamide (150 µg/mL) in comparison with wild type and other mutants was more capable of remediating chromium. At the end of 18 days, from the chrome electroplating effluent containing chromium (490 mg/100mL), the wildtype could remove 74% (362.6 mg/100 mL), UV radiation induced mutant removed 83% (406.7 mg / 100 mL) whereas acrylamide induced mutants removed 96.67% (470.4 mg/100 mL) of chromium. Enzyme assays confirmed involvement of enzymes at sub cellular level in chromium remediation.

Recovery of phosphorus and metallic nickel along with HCl production from electroless nickel plating effluents: The key role of three-compartment photoelectrocatalytic cell system

A three-compartment photoelectrocatalytic (PEC) cell system combined with ion exchange and chemical precipitation was proposed to recover phosphorus and nickel from electroless nickel plating effluents containing hypophosphite (H2PO2−) and nickel ions (Ni2+). Ion exchange was used to concentrate and separate Ni2+ and H2PO2−. As a key unit, the established PEC system consisted of TiO2/Ni-Sb-SnO2 photoanode and Ti cathode. With 25.8 mM NaH2PO2 and 500 mM NiCl2, 100 % H2PO2− was oxidized to PO43− in the anode cell, 78 % Ni2+ was recovered as metallic Ni in the cathode cell, and 900 mM HCl was obtained in the middle cell within 24 h at 3.0 V. Based on quenching experiments and ESR technique, OH radicals were mainly responsible for H2PO2− oxidation. In situ Raman spectroscopy indicated that Ni2+ initially reacted with OH− to form α-Ni(OH)2, which was gradually reduced to metallic Ni. Fortunately, a slight pH decrease in the cathode cell in the three-compartment cell system was beneficial for Ni2+ reduction to Ni°. The obtained PO43− was recovered by chemical precipitation. Finally, recovery of phosphorus and metallic nickel along with HCl production from an actual electroless nickel plating effluents in terms of efficiency, cost-benefit, and stability assessment were demonstrated.

Recovery of Phosphorus from Hypophosphite-Laden Wastewater: A Single-Compartment Photoelectrocatalytic Cell System Integrating Oxidation and Precipitation.

Recovery of phosphorus through precipitation from hypophosphite-laden wastewater is more difficult than from orthophosphate-laden wastewater because of the higher solubility of hypophosphite (H2PO2-). Herein, a single-compartment photoelectrocatalytic (PEC) cell system consisting of a TiO2/Ni-Sb-SnO2 bifunctional photoanode and an activated carbon fiber (ACF) cathode with dosing Fe2+ ions was developed for recovery of phosphorus in the form of FePO4 from hypophosphite-laden wastewater. In the PEC process, H2PO2- with an initial concentration of 1.0 mM was completely oxidized and recovered within 30 min at 3.0 V, and the pseudo-first-order rate constant of H2PO2- oxidation was ∼4 times than that in the electrocatalytic process and even ∼89 times than that in the photocatalytic process. The bifunctional photoanode can simultaneously generate •OH radicals and O3; the ACF cathode can electrogenerate H2O2; H2O2, O3, and the added Fe2+ can interact with each other to produce •OH radicals and Fe3+ ions. •OH radicals mainly from the Fenton process were responsible for oxidation of H2PO2- to PO43-, which immediately combined with Fe3+ to form FePO4 at the optimized conditions to realize recovery of phosphorus. The long-term stability of this system was demonstrated. The efficiency for actual electroless nickel plating effluents was exhibited.

Molecular identification guided process design for advanced treatment of electroless nickel plating effluent

It has been long desired but challenging to forward the advanced treatment of wastewater from empirical trials towards scientific design due to the lack of molecular insight into the pollutants of concern. Herein, we first established a systematic methodology to identify the ligands of Ni(II)-complexes in an electroless nickel (EN) plating effluent. The presence of N-containing groups in the ligands of most Ni(II)-complexes was verified by time-aligned ICP-MS and ESI-HRMS, implying the suitability of autocatalytic ozonation for efficient decomplexation. Thereby, a combined process was proposed on the basis of ozonation to achieve over 83% decomplexation of Ni(II) (initially at 0.36 mg/L), followed by selective Ni(II) sequestration for resource recovery. Combinational LC-MS systems revealed the ozonation-induced fragmentation or elimination of most Ni(II)-complexes as well as the structural change of the residual complexed molecules. The released free Ni(II) was further sequestrated by a nanocomposite of hydrated Zr(IV) oxide confined in a polymeric cation exchanger (nHZO@PCE). The fixed-bed working capacity of nHZO@PCE (∼550 BV) for the ozonated EN plating effluent was over 18 times that of the cation exchanger host (∼30 BV) at the breakthrough point of 0.10 mg Ni/L. More attractively, five adsorption-regeneration cycles demonstrated the great potential of the hybrid adsorbent for sustainable utilization. This study is believed to shed new light on how to design rational processes for advanced treatment of real wastewater based on molecular identification.

Expulsion of Zn from the Downstream of Metal Plating Effluent onto Modified Agricultural Adsorbent Prepared from Peanut Shell

Present work deals with the removal of Zinc (Zn) from metal plating industry effluent (MPE) using peanut husk as a modified agricultural adsorbent (MAA). The adsorption of zinc from metal plating effluent has been investigated along with various adsorbent parameters. The MPE was investigated for various parameters like pH, adsorbent doze dose, contact time, initial zinc concentration and temperature. The maximum removal efficiency of zinc was found to be (75.85 %) at pH 3.5 and time 250 min). The sludge obtained after adsorption has been filtered followed by drying which can be used in a boiler furnace as a fuel.

Removal of chromium (VI) and lead from electroplating effluent using electrocoagulation

ABSTRACTThe present study deals with the treatment of electro plating effluent (EPE) by electrocoagulation (EC) using iron as a sacrificial electrode. The initial concentration of chromium (VI) and lead (Pb) is found to be 55.3 and 3.5 mg/dm3 in EPE. With four-plate configurations, a current density (CD) = 73.5 A/m2 and pH = 3.5 was found to be best. At this operating condition, maximum 91.7% Cr (VI) (i.e., 4.92 mg/dm3) and 91.3% Pb (i.e., 0.304 mg/dm3) removal obtained in 90-min EC. Anode consumption was increased with a decrease in pH. It was also observed that energy consumption increased with an increase in pH. The settling characteristics of EC treated sludge were also analyzed at different pH and settling at pH 9.5 was found to best. Study indicated that EC treatment is successfully applicable to treat heavy-metal-oriented waste water. In addition, this technique is very effective to treat real waste water (electroplating effluent) along with minimum cost.

Nickel speciation of spent electroless nickel plating effluent along the typical sequential treatment scheme

The electroless nickel (EN) industry has suffered from the reduction in Ni concentration to lower than 0.1 mg/L. Hence, Ni speciation along a typical sequential treatment scheme has important implications to optimize the design of advanced treatment. For the first time, we revealed the Ni speciation in segmented EN outfall effluents by virtue of multiple analytical methods. After ensuring all the Ni-bearing complexes were completely dissolved by size-fractioned ultrafiltration trials, customized mass spectra analysis was conducted. In a series of ICP-MS assays, the potential polyatomic interfering species was primarily excluded. The chromatography hyphenated IC-ICP-MS and SEC-ICP-MS results demonstrated that the dominant Ni species in the EN effluents was similar to EDTA-Ni but with a smaller size. The LC-MS experiment further distinguished several typical Ni-bearing complexes. Although Ni concentration declined continuously along the treatment scheme, the number of detected Ni-bearing complexes gradually increased but with lower molecular weights. Most of the detected mononuclear complexes had higher indexes of hydrogen deficiency (IHD) than EDTA-Ni, whereas it was believed that the similar stereo ring shape was widespread in the EN effluent. Considering the efficient Ni decrease after the Fenton unit, further post-treatment approaches featuring higher active radical yields were suggested.

Spectroscopic signature of branched polyaniline nanotubules decorated with nanospheres as an adsorbent for chromium

Branched Polyaniline tubules decorated with nano polyaniline structures (PANI) were obtained by self-assembly during slow polymerization in strongly acidic conditions at 5 °C. The surface area of PANI was found to be 37.6716 m²/g with a pore size of 149.6430 Å corresponding to a maximum pore volume of 0.08255 cm³/g. Thermogravimetric analysis indicated a three step weight loss attributed to loss of water, chloride and degradation of PANI. The potential of PANI in the acid doped form was investigated for Cr6+ ion removal. The effects of operating parameters including pH, contact time and Cr6+ concentration were examined by batch adsorption experiments. Optimum adsorption occurred at pH 5 with Langmuir monolayer adsorption capacity Qmax of 182 mg/g. The adsorption process was diffusion controlled and was governed by pseudo second-order kinetics. The adsorption data were well fitted with Freundlich, Halsey and Elovich isotherm models indicating interactive and multilayer nature of the adsorption process. The applicability of PANI for removal of chromium from plating effluent was demonstrated.

Sequential application of Fenton and ozone-based oxidation process for the abatement of Ni-EDTA containing nickel plating effluents

Treatment of Ni-EDTA in industrial nickel plating effluents was investigated by integrated application of Fenton and ozone-based oxidation processes. Determination of integrated sequence found that Fenton oxidation presented higher apparent kinetic rate constant of Ni-EDTA oxidation and capacity for contamination load than ozone-based oxidation process, the latter, however, was favorable to guarantee the further mineralization of organic substances, especially at a low concentration. Serial-connection mode of two oxidation processes was appraised, Fenton effluent after treated by hydroxide precipitation and filtration negatively affected the overall performance of the sequential system, as evidenced by the removal efficiencies of Ni2+ and TOC dropping from 99.8% to 98.7%, and from 74.8% to 66.6%, respectively. As a comparison, O3/Fe2+ oxidation process was proved to be more effective than other processes (e.g. O3-Fe2+, O3/H2O2/Fe2+, O3/H2O2-Fe2+), and the final effluent Ni2+ concentration could satisfied the discharge standard (<0.1 mg L−1, China) under the optimal conditions (H2O2 dosage of 1.0 mL L−1, Fe2+: H2O2 mole ratio of 1.46, and reaction time of 10 min for Fenton reaction, initial influent pH of 3.0, O3 dosage of 252 mg L−1, Fe2+ of 150 mg L−1, and reaction time of 30 min for O3/Fe2+ oxidation). Furthermore, pilot-scale test was carried out to study the practical treatability towards the real nickel plating effluent, revealing the effective removal of some other co-existence contaminations. And Fenton reaction has contributed most, with the percentage ranging from 72.41% to 93.76%. The economic cost advantage made it a promising alternative to the continuous Fenton oxidation.

One-pot synthesis of Mn3O4/graphitic carbon nanoparticles for simultaneous nanomolar detection of Pb(II), Cd(II) and Hg(II)

In this paper, a facile one-step sucrose–nitrate decomposition method has been proposed to synthesis Mn3O4 nanoparticles (Mns)/graphitic carbon. The prepared material has been characterized by X-ray diffraction, Fourier transform infrared spectrometer, surface area analysis and transmission electron microscopy. The prepared Mns/graphitic carbon is drop-casted on glassy carbon electrode to allow the fabrication of electrochemical sensors for the simultaneous detection of Pb(II), Cd(II) and Hg(II) at nanomolar (nM) levels in aqueous solutions via differential pulse anodic stripping voltammetry. The proposed Mns/graphitic carbon sensors exhibit a wide linear range from 20 to 680 nM towards the simultaneous sensing of Cd(II), Pb(II) and Hg(II), and the corresponding limits of detection were found to be 0.48 × 10−11, 9.66 × 10−11 and 0.51 × 10−11 M, respectively. The practical application of the proposed sensor is evaluated within a real battery, industrial and chrome plating effluents.

Chitosan supramolecularly cross linked with trimesic acid – Facile synthesis, characterization and evaluation of adsorption potential for chromium(VI)

A facile synthesis of Chitosan Supramolecularly cross-linked with Trimesic Acid (CTMA) is reported in this work. The adsorption potential of CTMA for removal of hexavalent chromium was evaluated and the influence of pH, temperature, contact time and adsorbent dose on the adsorption process was investigated. The experimental results showed that CTMA could efficiently adsorb Cr6+ and partially reduce it to the less toxic Cr3+ state. The maximum adsorption capacity of CTMA for Cr6+ was found to be 129.53mg/g at pH 2.0. CTMA and chromium loaded CTMA were characterised by FT-IR, Raman, TGA-DSC, SEM-EDX, XRD, ESR and XPS spectroscopic techniques. Chitosan was observed to be cross- linked with TMA via ionic, hydrogen bonding and pi–pi supramolecular interactions while adsorption of chromium onto CTMA was by electrostatic forces and hydrogen bonding. From the observed results it was evident that CTMA was successfully applied for simultaneous removal of chromium, lead and iron from chrome plating effluent.

Advanced oxidation removal of hypophosphite by O3/H2O2 combined with sequential Fe(II) catalytic process

Elimination of hypophosphite (HP) was studied as an example of nickel plating effluents treatment by O3/H2O2 and sequential Fe(II) catalytic oxidation process. Performance assessment performed with artificial HP solution by varying initial pH and employing various oxidation processes clearly showed that the O3/H2O2─Fe(II) two-step oxidation process possessed the highest removal efficiency when operating under the same conditions. The effects of O3 dosing, H2O2 concentration, Fe(II) addition and Fe(II) feeding time on the removal efficiency of HP were further evaluated in terms of apparent kinetic rate constant. Under improved conditions (initial HP concentration of 50 mg L−1, 75 mg L−1 O3, 1 mL L−1 H2O2, 150 mg L−1 Fe(II) and pH 7.0), standard discharge (<0.5 mg L−1 in China) could be achieved, and the Fe(II) feeding time was found to be the limiting factor for the evolution of apparent kinetic rate constant in the second stage. Characterization studies showed that neutralization process after oxidation treatment favored the improvement of phosphorus removal due to the formation of more metal hydroxides. Moreover, as a comparison with lab-scale Fenton approach, the O3/H2O2─Fe(II) oxidation process had more competitive advantages with respect to applicable pH range, removal efficiency, sludge production as well as economic costs.

Chitosan A Low Cost Adsorbent for Electroplating Waste Water Treatment

In the wake of rapid industrialization, urbanization and population explosion, the basic needs of life viz. air, water and land are continuously being polluted over the period of the time. Effluent waste from Electroplating industries considerably pollutes the environment. It is of major concern as the discharged heavy metals such as Cr6+, Zn2+, Cu2+, Pb2+, Cd2+ etc. are harmful to the ecosystem. Although various techniques are used for the removal of heavy metals. Bioadsorption process is one of the mainly adopted methods to recycle and reuses the wastewater. Hence the present study focused in assessing the usage of chitosan, a marine biopolymer extracted from the locally available shells of crab Portunus pelagicus as an adsorbent. The ability of chitosan to adsorb heavy metals such as Cr6+, Zn2+, Cu2+, Pb2+, Cd2+ from the electroplating industry waste water effluents was investigated at different pH. It was found that maximum adsorption of heavy metals occurred at a pH range between 5 to 7. The study results indicate that the cost incurred towards extraction was less than that the cost incurred by the commercial treatment facilities. The -OH and –NH2 functional groups in chitosan facilitate the adsorbent function and make it an ideal adsorbent for the treatment of wastewater. This study brings to light that chitosan is function as an economically useful adsorbent for the treatment of electro plating effluent containing heavy metals.

Adsorption of chromium from aqueous solutions using crosslinked chitosan–diethylenetriaminepentaacetic acid

Chitosan (CH) and its derivatives have been the focus of attention for researchers as potential adsorbents for heavy metal removal. The adsorption potential of chitosan cross-linked with diethylenetriaminepentaacetic acid (CD) for Cr6+ was investigated. CD was characterized by FTIR, XRD, TGA, XPS and ESR techniques. Batch experiments were conducted to optimize the parameters affecting the adsorption of chromium. The optimum pH was found to be 3 and the adsorption process was found to be exothermic. Adsorption isotherms were determined and the maximum adsorption capacity of CD for chromium was found to be 192.3mg/g which was higher than the adsorption capacity of the adsorbents reported in literature. The thermodynamic parameters, such as Gibbs free energy, changes in enthalpy and changes in entropy change were also evaluated. XPS and ESR studies revealed that Cr6+ adsorbed onto CD was reduced to Cr3+. The efficacy of CD for removal of Cr6+ from chrome plating effluent was demonstrated.

A kinetic model to describe the nickel electro-recovery from industrial plating effluents under variable electrolyte conductivity

A comprehensive model is developed to account for the kinetics of nickel electro-recovery from industrial plating effluents, typically containing low sulfate (1.25–18.73molm−3), chloride (0.49–7.41molm−3) and borates concentrations (9.96–150molm−3) at pH 4. The model is developed for linear sweep voltammetry considering the mass-transport of six species in solution under stagnant conditions: Ni2+, NiSO4(aq), H+, Na+, SO42− and Cl−, and accounting for the kinetic discharges of Ni2+, NiSO4(aq), H+ and H2O on the substrate. Additionally, the challenges imposed for the analysis of different baths with variable electrolyte conductivities (397–4202μScm−1), migration effects and diffusion coefficients depending on ionic strength (Nernst–Hartley equation), are incorporated into the model to simulate the real conditions of the plating effluents. When only one nickel species (Ni2+) is considered in the model, large deviations are observed between the model and the experimental data at intermediate and high overpotentials of the voltammograms. On the other hand, very good fits are obtained when two nickel species (Ni2+, NiSO4(aq)) are introduced in the model for the experiments conducted at variable electrolyte conductivity. The prediction capabilities of the model are clearly proven by simulating different experimental data generated at constant conductivities, using a single set of kinetic parameters calculated from the fitting stage. The model is developed in a general form such that it can be extended for the robust analysis of other systems or experimental conditions.

Removal of chromium from water effluent by adsorption onto &amp;lt;i&amp;gt;Vetiveria zizanioides&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;Anabaena&amp;lt;/i&amp;gt; species

Bioadsorption phenomenon is more or less like a chemical reaction and several parameters are bound to affect the process. The pH, amount of adsorbent and agitation time influence the biosorptive potentiality. Hence, the present study on adsorption of Cr(VI) by activated Vetivera roots and Blue green algae Anabaena supports that it is an effective low cost adsorbent for the removal of Cr(VI) from plating effluent. Langmuir and Freundlich adsorption isotherm correlate the equilibrium adsorption data. In batch experiments both Vetiveria and Anabaena species were found to be cost effective biosorbent for the efficient removal of Cr(VI) from the effluent and comparatively Anabaena species was found to adsorb maximum Cr(VI) (88.86%) at a low contact time of 60 min. The data obtained from the experiments and modeling would prove useful in designing and fabricating an efficient treatment plant for Cr(VI) rich effluent.

Physico-chemical Characterization of Water Body with Special Reference to Battery, Power Sources and Metal Plating Effluents

The World is facing a tremendous set of environmental problems which are due to the contaminated ground water and hazardous waste effluents coming out of process industries due to advanced industrialization in different field. Thus, it is essential to rectify this problem.

Electrochemical recovery of nickel from nickel sulfamate plating effluents

Nickel sulfamate solutions are widely used for industrial nickel plating, when electrodeposits with low stress are required. Partial decomposition of sulfamate with decreasing pH below ca. 2.5 degrades the properties of nickel electrodeposits, decreases the charge yield and results in spent solutions, from which nickel must be recovered before they could be discharged to sewers. Results are reported of charge yields for nickel recovery from an industrial sulfamate effluent, using an electrochemical reactor operated at constant current in batch-recycle mode and incorporating a nickel mesh cathode, a Ti/Ta2O5–IrO2 mesh anode and a cation-permeable membrane to prevent anodic oxidation of sulfamate. A micro-kinetic model was developed, treating the processes of nickel(II) and proton reduction in sulfamate solutions as two multi-step reactions involving adsorbed intermediates, Ni ads I and Hads, respectively. The unknown kinetic parameters were obtained using gPROMS software by iterative fitting of the model to experimental data obtained over a range of nickel(II) concentrations and bulk solution pH, enabling evaluation of nickel(II) reduction charge yields as a function of nickel(II) concentration, bulk pH and electrode potential. A model combining the micro-kinetic equations with mass and charge balances on the reactor was used to determine the control parameters for electrochemical recovery of elemental metal from nickel(II) in batch-recycle mode. It was determined experimentally that a decrease in catholyte pH to values below ca. 2.5 resulted in a decrease in nickel(II) reduction charge yields to values below 0.9. The decrease in catholyte pH, caused by the flux of protons from the anolyte where they were generated via anodic oxygen evolution, was obviated by continuous addition of NaOH at a rate determined by the model, permitting nickel(II) recovery with an average charge yield of 0.94.