Alkaline Reagents Research Articles

Morphology control and characterizations of nickel sea-urchin-like and chain-like nanostructures

Under refluxing conditions in alcoholic solution, nickel sea-urchin-like particles and nickel spherical nanoparticles self-assembled into nanochains have been synthesized by a simple wet chemical method in which aqueous hydrazine (N 2H 4·H 2O) was used as reducing reagent and sodium hydroxide (NaOH) was used as alkaline reagent. The structure and morphology of the final nanoparticle products are controlled by the adding sequence of N 2H 4·H 2O, NiCl 2, and NaOH solutions. The sea-urchin-like Ni particles and the spherical Ni nanoparticles self-assembled into nanochains were obtained by varying the adding sequence of these reactants. In addition, a relatively higher temperature is advantageous to the formation of both sea-urchin-like and chain-like Ni nanoparticles. Finally, the dependence of the magnetic parameters such as coercivity ( H c) and squareness ( M γ / M s) on the morphology of as-prepared Ni nanocrystals will be discussed.

Effects of Particle Size and Starch Damage of Flour and Alkaline Reagent on Yellow Alkaline Noodle Characteristics

ABSTRACTA hard white spring wheat was milled to yield three patent flours with different starch damage levels by manipulating reduction grinding conditions, and each flour was sieved to give three different particle sizes (85–110, 110–132, 132–183 μm). Raw alkaline noodles were prepared using either 1% w/w kansui (sodium and potassium carbonates in 9:1 ratio) or 1% w/w sodium hydroxide. Noodles prepared with sodium hydroxide were significantly brighter, less red, and more yellow than those made with kansui. Differences in noodle color among flour treatments were evident but were attributable to differences in flour refinement rather to than particle size or starch damage. Noodles were rested for 1 hr after processing before cooking. Alkaline reagent was the main factor associated with cooking loss, being ≈50% greater for sodium hydroxide noodles because of higher pH compared with kansui noodles. Cooked sodium hydroxide noodles were thicker than kansui noodles, and cooked strands for both noodle types became thicker as starch damage increased and as particle size became coarser. Instrumental assessment of cooked noodle texture showed that maximum cutting stress (MCS), resistance to compression (RTC), recovery (REC), stress relaxation time (SRT), chewiness (CHE), and springiness (SPR) were influenced by the type of alkaline reagent. Flour particle size and starch damage also influenced noodle texture but the magnitude of the effects and the trends were dependent on alkaline reagent. MCS of kansui noodles was much greater than for sodium hydroxide noodles. MCS of kansui noodles increased as starch damage increased but, in contrast, MCS of sodium hydroxide noodles decreased with increasing starch damage. REC of kansui noodles increased with increasing starch damage and decreased with larger particle size, whereas for sodium hydroxide noodles REC decreased with increasing starch damage and declined dramatically with larger particle size. Kansui noodles exhibited significantly shorter SRT than sodium hydroxide noodles. SRT of kansui noodles was only moderately affected by starch damage and particle size, whereas for sodium hydroxide noodles, SRT became much shorter as flour became coarser and starch damage became higher. CHE of kansui noodles was greater than for sodium hydroxide noodles. CHE of kansui noodles increased as starch damage increased. In contrast, CHE of sodium hydroxide noodles decreased as starch damage increased and also decreased as flour became coarser. SPR of both noodle types decreased as flour became coarser and starch damage became greater. On the basis of these experiments, flour of smaller particle size is an asset to the cooking quality of sodium hydroxide noodles, but high starch damage is to be avoided. For kansui noodles, the impact of flour particle size on cooked noodle texture was less evident and low starch damage, rather than high starch damage, was an asset.

Field application of calcite Dispersed Alkaline Substrate (calcite-DAS) for passive treatment of acid mine drainage with high Al and metal concentrations

Abstract Passive treatment systems are widely used for remediation of acid mine drainage (AMD), but existing designs are prone to clogging or loss of reactivity due to Al- and Fe-precipitates when treating water with high Al and heavy metal concentrations. Dispersed alkaline substrate (DAS) mixed from a fine-grained alkaline reagent (e.g. calcite sand) and a coarse inert matrix (e.g. wood chips) had shown high reactivity and good hydraulic properties in previous laboratory column tests. In the present study, DAS was tested at pilot field scale in the Iberian Pyrite Belt (SW Spain) on metal mine drainage with pH near 3.3, net acidity 1400–1650 mg/L as CaCO3, and mean concentrations of 317 mg/L Fe (95% Fe(II)), 311 mg/L Zn, 74 mg/L Al, 20 mg/L Mn, and 1.5–0.1 mg/L Cu, Co, Ni, Cd, As and Pb. The DAS-tank removed an average of 870 mg/L net acidity as CaCO3 (56% of inflow), 25% Fe, 93% Al, 5% Zn, 95% Cu, 99% As, 98% Pb, and 14% Cd, but no Mn, Ni or Co. Average gross drain pipe alkalinity was 181 mg/L as CaCO3, which increased total Fe removal to 153 mg/L (48%) in subsequent sedimentation ponds. Unfortunately, the tank suffered clogging problems due to the formation of a hardpan of Al-rich precipitates. DAS lifetime could probably be increased by lowering Al-loads.

Preparation of well-dispersed spherical nickel powders with uniform size via mild solvothermal route

Well-dispersed spherical nickel powders with uniform size were synthesized via a mild solvothermal route in which aqueous hydrazine was used as reducing agent without any alkaline reagent or surfactant introduced. The as-prepared products were characterized by XRD, FESEM, XPS, and TG. Different influencing factors including solvent, concentration, reaction time, and temperature on the morphology and size of the final products were examined. The size of the spherical nickel powders is tunable from 150 to 800 nm. The obtained nickel powders have little Ni(OH)2 on the surface and exhibit excellent oxidation resistance. In addition, the formation process was discussed on the basis of the experimental results.

Coprecipitation of radium with barium sulfate from salt solutions

Coprecipitation of radium with barium sulfate from highly concentrated NaCl solutions is studied, including the effects of the initial solution composition, alkaline reagent (CaO, NaOH), supporting electrolyte (NaCl) concentration, and pH. The process is promoted by high NaCl concentration in the initial solution, which is due to structural transformation and change in the sorption activity of the BaSO4 precipitate in salt solutions. The results obtained were applied to recovery of radium from process solutions in chlorination of loparite concentrates.

Pilot scale SO2 control by dry sodium bicarbonate injection and an electrostatic precipitator

AbstractA 500 actual cubic feet gas per minute (acfm) pilot‐scale SO2 control study was undertaken to investigate flue gas desulfurization (FGD) by dry sodium sorbents in 400°F (204.5°C) flue gases emitted from a coal fired boiler with flue gas concentrations between 350 and 2500 ppm SO2. Powdered sodium alkaline reagents were injected into the hot flue gas downstream of the air preheater and the spent reagents were collected using an electrostatic precipitator. Three different sorbents were used: processed sodium bicarbonate of two particle sizes; solution mined sodium bicarbonate, and processed sodium sesquicarbonate. SO2 concentrations were measured upstream of the reagent injection, 25‐ft (7.62 m) downstream of the injection point, and downstream of the electrostatic precipitator. SO2 collection efficiencies ranged from 40 to 80% using sodium bicarbonate stoichiometric ratios from 0.5 to 3.0. Much of the in‐duct SO2 removal occurred during the first second of reagent reaction time, indicating that the sulfur dioxide–sodium reaction rates may be faster than have been measured for fixed bed measurements reported in the literature. © 2007 American Institute of Chemical Engineers Environ Prog, 2007

Rapid uranium preconcentration and separation method from fresh water samples for total U and 235U/ 238U isotope ratio measurements by ICP-MS

A simple and rapid method using TRU resin cartridges (Eichrom Technologies, Inc., USA) and quadrupole ICP-MS for total uranium (U) and 235U/ 238U isotope ratio measurements in fresh water samples was investigated. After U extraction on the resin by sample solution loading, three alkaline reagents, tetramethyl ammonium hydroxide (TMAH), NaOH and NH 4OH were studied for U elution behavior from the resin cartridges and applicability of these eluates was evaluated with respect to direct introduction to ICP-MS. Among the studied eluants, TMAH showed the best results with high U recovery and no counting interferences with internal standard elements such as thallium and bismuth. Moreover, U in water samples was separated from many major and minor elements with the TRU cartridges. Almost all U was concentrated in 10 mL of 0.014 M TMAH in 2 h using 200 mL of water sample.

Inorganic nitrogen removal of toilet wastewater with an airlift external circulation membrane bioreactor

Removal of inorganic nitrogen (inorganic-N) from toilet wastewater, using a pilot-scale airlift external circulation membrane bioreactor (AEC-MBR) was studied. The results showed that the use of AEC-MBR with limited addition of alkaline reagents and volumetric loading rates of inorganic-N of 0.19–0.40 kg inorganic-N/(m 3.d) helped achieve the desired nitrification and denitrification. Furthermore, the effects of pH and dissolved oxygen (DO) on inorganic-N removal were examined. Under the condition of MLSS at 1.56–2.35 g/L, BOD 5/ammonia nitrogen (NH 4 +-N) at 1.0, pH at 7.0–7.5, and DO at 1.0–2.0 mg/L, the removal efficiencies of NH 4 +-N and inorganic-N were 91.5% and 70.0%, respectively, in the AEC-MBR. The cost of addition of alkaline reagent was approximately 0.5–1.5 RMB yuan/m 3, and the energy consumption was approximately 0.72 kWh/m 3 at the flux of 8 L/(m 2.h).

Rheological properties of hydrated zirconium dioxide

The sol–gel transition of the ZrOCl 2–alkaline reagent (MeOH, Me(OH) 2, MeHCO 3, Me 2CO 3, etc.)–NH 4Ac system has been studied using rheological measurements. Hydrated zirconium dioxide has been prepared with the use of new two-stage neutralization scheme of the initial ZrOCl 2 solution. At the first step any alkaline reagent can be used. On the second step the solution of the slightly basic agents with pH less than 10, for example NH 4Ac, NaHCO 3 etc. added in one sitting, have been used for neutralization to obtain final product. The effect of temperature, molar ratio of initial reagents, shear rate, pH of zirconium containing gels on the gelation process, namely on the change of dynamic viscosity and shear modules of temporary rapid and slow elastic deformations has been investigated. The structure formation processes of hydrated zirconium dioxide have been studied with dynamic technique and method of physico-chemical mechanics. The last method possesses some essential advantages allowing the definition of most factors, which influence on structure and mechanical properties of investigated samples and the complete analysis of the investigated system without its destruction.

Rise in the pH of an Unfrozen Solution in Ice Due to the Presence of NaCl and Promotion of Decomposition of Gallic Acids Owing to a Change in the pH

Oxidative decomposition of gallic acid occurs in alkaline solutions but hardly arises in acidic solutions. We have found that the addition of sodium chloride promotes the decomposition of gallic acid caused by freezing even under neutral and acidic conditions. Even at pH 4.5, gallic acid was decomposed by freezing in the presence of NaCl; however, in the absence of NaCl, it was hardly decomposed by freezing at pH lower than 7. Chloride ions are more easily incorporated in ice than sodium ions when the NaCl solution is frozen. The unfrozen solution in ice becomes positively charged, and as a result, protons transfer from the unfrozen solution to the ice. We measured the pH in the unfrozen solution which coexists with single-crystal ice formed from a 5 mmol dm(-3) NaCl solution and determined the pH to be 8.6 at equilibrium with CO(2) of 380 ppm or 11.3 in the absence of CO(2) compared to pH 5.6 in the original solution. From the model calculation performed for gallic acid solution in the presence of 5 mmol dm(-3) NaCl, it can be estimated that the amount of OH(-) transferred from the ice to the solution corresponds to 1.26 x 10(-5) mol dm(-3). The amount of OH(-) transferred is concentrated into the unfrozen solution and affects the pH of the unfrozen solution. Therefore, the pH in an unfrozen gallic acid solution in ice becomes alkaline, and the decomposition of gallic acid proceeds. It is expected that other base-catalyzed reactions in weakly acidic solutions also proceed by freezing in the presence of NaCl without the need for any alkaline reagents.

Selective synthesis and characterization of sea urchin-like metallic nickel nanocrystals

Sea urchin-like nanobelt-based and nanorod-based metallic nickel nanocrystals have been selective synthesized via a hydrothermal reduction route in which sodium hydroxide was used as alkaline reagent and aqueous hydrazine (N 2H 4·H 2O) was used as reducing agent. The morphology and structure of final products could be easily controlled by adjust process parameters such as hydrothermal time, reaction temperature and alkaline concentration. Surfactant cetyltrimethylammonium bromide (CTAB) was also important parameter influencing the morphology of the products. The morphology and phase structure of the final products have been investigated by X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The probable formation mechanism of the sea urchin-like metallic nickel nanocrystals was discussed on the basis of the experimental results.

Treatment of Acid Sulfate Soil Drainage By Direct Application of Alkaline Reagents

Due to the episodic nature of rainfall and the high dissolved metal concentrations in the acid sulfate soil catchment of Clothiers Creek (NSW, Australia), active treatment was considered more appropriate than passive treatment. Alkaline reagents were added to oxidised shallow drains to remove acidities ranging from 438 to 1,837 mg/L CaCO3. A fine limestone slurry was produced from the pounding together of limestone rock fragments within a rotating drum and, on addition to drain waters, was found to remove acidity to varying degrees of effectiveness (from 12 to 100%). The efficiency decreased as the pH of the water approached neutrality due to calcite saturation and the slow reaction rate of limestone at high pH. Hydrated lime powder was also mixed with drain water in the rotating drum though most mixing occurred once the slurry entered the drain where efficiencies ranging from 67 to 89% were observed. A powdered mixture of MgCO3 and CaCO3 was only 11% effective in treatment of the drainage water due to the slow rate of reaction of MgCO3. Whilst the active treatment system was capable of treating a large acidity flux (particularly using hydrated lime) it required regular addition of reagent and the dosing of hydrated lime was particularly difficult to control. Future designs of this active treatment system should be automated to prevent adverse aquatic impacts due to overdosing.

Effects of Salt and Alkaline Reagents on Dynamic Rheological Properties of Raw Oriental Wheat Noodles

ABSTRACTTo gain further understanding of the functionality of ingredients in oriental wheat noodles, the rheological properties of raw noodles made using high protein (Red Bicycle) or low protein (Sandow) wheat flours and various additives (salt or alkaline reagents at concentrations of 0, 0.1, 0.5, 1.0, 2.0, 3.0, and 4.0%) were investigated using frequency sweep and temperature sweep oscillatory tests. Generally, both the elastic modulus(G′) and viscous modulus (G″) of raw noodles increased when various levels of salt or alkaline (kansui and NaOH) reagents were included in the formulation, with the exception of Red Bicycle noodles where the G″ was not significantly affected by the salt. The G′was significantly decreased in the presence of sodium chloride at concentrations ≤4.0% and kansui at <0.5%. The change in rheological properties of raw noodles was related to the wheat flour quality, type, level of additive, and frequency. The G′, G″, phase angle, and complex viscosity changed in a similar pattern when raw noodles were heated from 25 to 100°C. These parameters decreased initially with increasing temperature until they reached a valley and then increased either to a plateau or continuously in noodles containing kansui. The appearance of valley points at 75.5 and 77.2°C during heating of Sandow and Red Bicycle noodles containing salt, and 89.4, and 83.2°C during heating of Sandow and Red Bicycle noodles containing kansui, respectively, was not associated with starch gelatinization as determined using differential scanning calorimetry. The continuous increase in G′, G″, and complex viscosity observed with noodles containing kansui during the hold period at 100°C was attributed to the high pH environment and not to the inactivation of α‐amylase.

Chemical Stability of Acid Rock Drainage Treatment Sludge and Implications for Sludge Management

To assess the chemical stability of sludges generated by neutralizing acid rock drainage (ARD) with alkaline reagents, synthetic ARD was treated with hydrated lime (batch and high-density sludge process), limestone, and two proprietary reagents (KB-1 and Bauxsol). The amorphous metal hydroxide sludge produced was leached using deionized water, U.S. EPA methods (toxicity characteristic leaching procedure, synthetic precipitation leaching procedure), and the new strong acid leach test (SALT), which leaches the sludge with a series of sulfuric acid extractant solutions; the pH decreases by approximately 1 pH unit with each test, until the final pH is approximately 2. Sludges precipitated by all reagents had very similar leachabilities except for KB-1 and Bauxsol, which released more aluminum. SALT showed that lowering the pH of the leaching solution mobilized more metals from the sludges. Iron, aluminum, copper, and zinc began to leach at pH 2.5-3, approximately 4.5, approximately 5.5, and 6-6.5, respectively. The leachability of ARD treatment sludges is determined by the final pH of the leachate. A higher neutralization potential (e.g., a greater content of unreacted neutralizing agent) makes sludges inherently more chemically stable. Thus, when ARD or any acidic metalliferous wastewater is treated, a choice must be made between efficient reagent use and resistance to acid attack.

Sequential Injection Titration with Spectrophotometric Detection for the Assay of Acidity in Fruit Juices

A simple sequential injection analysis (SIA) with spectrophotometric detection for an assay of acidity in fruit juice was investigated. An alkaline reagent (sodium hydroxide), a sample and an indicator (phenolphthalein) were first aspirated and stacked as adjacent zones in a holding coil. With flow reversal through a reaction coil to the detector, zone penetration occurred, leading to a neutralization reaction that caused a decrease in the color intensity of the indicator being monitored for absorbance at 552 nm. The effects of various parameters were studied. Linear calibration graphs for acidities of 0.2 - 1.0 and 0.5 - 2.5% w/v citric acid as a standard, with a relative standard deviation of 1% (acidity of 0.3 - 0.6% w/v as citric acid, n=11) and a sample throughput of 30 samples h(-1), were achieved. The developed method was validated by a standard titrimetric method for assaying the acidity of fruit juice samples.

The influence of pyrite pre-oxidation on gold recovery by cyanidation

The influence of pyrite pre-oxidation in alkaline solutions on gold recovery by cyanidation from Twin Creek refractory gold ore in which pyrite was identified as the major sulfide mineral has been investigated with the aid of electrochemical measurements, leaching experiments, and direct analysis of reaction products for selected residues. It was found that gold recovery by cyanidation in bottle roll experiments mainly depended on the extent of pyrite pre-oxidation. The rate of pyrite oxidation in alkaline solutions measured by electrochemical measurements, including chronoamperometry and linear sweep voltammetry, increased with an increase in pH, potential, and temperature. All alkaline reagents used for the electrochemical measurements, NaOH, NH 4OH, Na 2CO 3 and Ca(OH) 2, showed a similar effect on pyrite oxidation kinetics. However, the results of alkaline pre-oxidation for pyrite of the Twin Creek refractory gold ore suggested that NaOH and Na 2CO 3/Ca(OH) 2 were superior to Ca(OH) 2. Without pre-oxidation, cyanide leachable gold was found to be only 20% which could be increased to 70% under appropriate pre-oxidation conditions. At the same time, cyanide consumption decreased from 2.5 kg/t ore to 1.5 kg/t ore. Selected residues after pre-oxidation and cyanidation were examined by X-ray diffraction. Backscattered electron images of pyrite particles in these residues were taken. The reaction products at the surface of pyrite particles were found to be iron-, silicon-, and calcium-bearing compounds with variable amounts of sulfur as determined by X-ray energy dispersion analysis. Additionally, some mineral fines, such as aluminum and/or potassium-bearing minerals, were found to be present at the partially oxidized pyrite surface.

The impact of sulphide oxidation on dissolved metal (Cd, Zn, Cu, Cr, Co, Ni, U) inputs into the Lot–Garonne fluvial system (France)

Results are presented from observation of dissolved metal concentrations and fluxes at 5 sites in the Lot–Garonne fluvial system known for its historic metal contamination. The contamination originates from the upstream Lot River where a small tributary (Riou-Mort River) drains a smelting-waste area. Unlike non-neutralised acid mine drainage systems, the Riou-Mort waters were not acidic (6.8 < pH < 8.0) due to application of alkaline reagents for neutralisation. Relatively high dissolved U concentrations (up to 1.1 μg L −1) were attributed to these reagents. High metal concentrations (e.g., up to 23 and 1190 μg L −1, for Cd and Zn, respectively) in the Riou-Mort water resulted from the oxidation of the sulphide phases within the smelting-wastes. Pyrite oxidation rate was estimated (5530 t a −1; 35.7 t km −2 a −1) from the total amount of SO 4 2 - discharged in the river water. The related dissolved metal inputs into the Lot River were, e.g., 0.55 and 35 t a −1 for Cd and Zn, respectively. The dissolved Cd fluxes in the Lot River corresponded to 65% of those in the downstream Garonne River. The dissolved Zn fluxes were even similar to those in the Garonne River. Mass balance calculations showed that, downstream the Riou-Mort/Lot River confluence, the exchange between dissolved and particulate phases accounted for the removal of 15% of Zn and 50% of Cd from the dissolved phase. The calculated annual dissolved metal fluxes at the outlet of the Lot–Garonne River system are significant at the global scale, as they represent 0.02–0.25% of the global river budget.

Densification of iron(III) sludge in neutralization

Acid mine drainage (AMD), of which iron is a substantial component, is a potential by-product in the mining industry. Conventional neutralization is a common approach to treat AMD, although it creates a major disposal problem due to the generation of voluminous sludge. Sludge recirculation improves solid density by slowing down the rate of neutralization and allowing the growth of precipitates, while existing solids act as seed particles by providing necessary surface area for precipitation. The mechanisms of iron sludge densification are not fully understood, mainly because of the complex nature of iron chemistry, and the variety of amorphous, polymeric oxides that could be formed. In this work, the effects of alkaline reagents, flocculant addition, and dosing sequence, on the precipitation of iron (III) hydroxide and densification of the recycled sludge were investigated. Slowly dissolving lime (Ca(OH) 2) was found to be more effective than caustic (NaOH) in producing sludge with higher solid contents. Polymers addition created stronger aggregates that could withstand shearing without significant size reduction, but the overall sludge density was lower than those produced without flocculant. Conditioning the sludge at pH between 3.5 and 4.5 by adding fresh lime in a specific dosing manner appeared to be conducive to the growth of large agglomerates. The final sludge solid content of ∼15 wt.% was considerably higher than others produced under different conditions. The plate-like structures of precipitates generated with more recycles in this instance, possibly helped ease the release of entrapped water between solids during shearing, thus producing sludge with higher solid density.

Determination of acetone in breath

A light emitting diode (LED)-based photometric method for the measurement of gaseous acetone in human breath is presented. The detection chemistry is based on the reaction of acetone with alkaline salicylaldehyde to form a colored product, which absorbs in the blue and can be monitored with GaN-based LEDs with emission centered at 465 nm. Gaseous acetone in breath is sampled with a porous membrane based diffusion scrubber (DS). The collected sample in the continuously flowing water carrier reacts with the reagent solution. We have used two approaches to collect breath acetone: the use of a face mask and a Mylar balloon as a collection bag. With the face mask approach, the expired air can be measured over long periods without major subject discomfort, balloon collection (5 l) permits four measurements from a single fill. The LED-based liquid core waveguide (LCW) absorbance detector utilized sapphire ball lenses to prevent exposure of other optical components to a hot alkaline reagent solution. The high refractive index of the final mixture permitted the use of an inexpensive fluorinated ethylene copolymer (FEP Teflon ®) tube as a 10 cm long LCW. The limit of detection (S/N = 3) is 14 ppbv gaseous acetone, and the linear range extends to 1.21 ppmv. The concentration range in 11 volunteer subjects ranged from 176 to 518 ppbv.

Pilot plant investigation on petrochemical wastewater treatmentfor the removal of copper and chromium with the objective of reuse

There has been great demand for development of technologies that remove toxic heavy metal ions from wastewater. Chemical precipitation operation is known to remove heavy metal ions from water. In this study applicability of alkaline reagents such as Ca(OH) 2 (lime) and NaOH (caustic soda) in removing copper and chromium ions were evaluated. Separation of heavy metals such as chromium compounds from petrochemical industries' cooling water wastes was achieved by conversion of hexavalent chromium, Cr(VI), to trivalent chromium, Cr(III). Maximum conversion occurred in the pH range of 2.0 and 2.3, adjusted by ferrous sulfate and sulfuric acid. Maximum precipitation of Cr(III) occurred at pH 8.7 with addition of Ca(OH) 2, followed by mixing and 2-h sedimentation. At the end, the concentration of chromate was reduced from 30 ppm to 0.01 ppm. In the case of copper, which is found in the form of cupro-ammonia in ammonia plant wastes, it was observed that the presence of ammonia in wastewater prevents effective chemical precipitation. Therefore, the quantity of ammonia was reduced by aeration. The optimum aeration rate was determined to be 70 L/min, and it was found that ammonia concentration reached equilibrium after 5.0 h o f aeration. Furthermore, hydroxide and carbonate methods were evaluated with respect to precipitation of heavy metals at bench scale, and the former was selected as the method of choice. The results obtained in the Jar test were then applied to pilot scale, and it was determined that the optimum pH for maximum copper precipitation was about 12.0 for both lime and caustic soda used in the hydroxide precipitation method. Lime was preferred due to economics and its high speed of precipitation. Finally, using established methods described here, the concentration of copper followed by coagulation with lime, mixing, 2-h sedimentation and filtration through Whatman 0.45 Am filters was reduced from 48.51 mg/L to 0.694 mg/L, which is below the environmental standards for water resources.