Gong Wenqi, Han Pei, Wang Hukun, Liu Yanju, Rao Boqiong
(School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan 430070, Hubei, China)
Abstract The process conditions and regeneration methods of the adsorbent materials prepared from recumbent stone-water quenching slag and recumbent stone-fly ash particles as well as their conditions for the removal of heavy metals in copper smelting industrial wastewater were investigated. The test results show that when the ratio of recumbent stone to water-quenched slag is 1:1, another 10% additive (IS) and 50% water are added, and the roasting temperature is 400℃, the granular adsorbent materials made are not only adsorptive, but also have a low dissipation rate. Under the condition of not adjusting the pH value of copper smelting industrial wastewater, the removal rate of Cu2+, Pb2+, Zn2+, Cd2+, Ni2+ was 98.2%, 96.3%, 78.6%, 86.2% and 64.2% respectively when the dosage of granular adsorbent material was 0.05 g/cm3, the reaction time was 40 min, and the adsorption temperature was 25°C (room temperature). The ratio of regolith to fly ash was 1:1, another 15% additive (IS) and 50% water were added, and the particle adsorbent material made at a roasting temperature of 500°C not only had a good adsorption effect, but also had a low dissipation rate. Under the condition of not adjusting the pH value of copper smelting industrial wastewater, the dosage of particle adsorbent material is 0.07g/cm3, the reaction time is 60 min, and the adsorption temperature is 25℃ (room temperature), the removal rate of Cu2＋, Pb2＋, Zn2＋, Cd2＋, Ni2＋ is 98.9%, 97.5%, 96.7%, 90.2%, 79.1%, respectively. The treated water complied with the national comprehensive sewage discharge standards (GB8978-1996) of the first-class standard. The adsorption saturated particle adsorbent material was regenerated with 1 mol/L sodium chloride solution with good effect. The particle adsorption material has the advantages of easy separation, reusable, good treatment effect, and broad application prospects [1-11].
Keywords Retentate; Water quenching slag; Fly ash; Particle adsorbent material; Regeneration; Copper smelting industrial wastewater
First author's biography:Gong Wenqi (1948-), male, Han nationality, native of Wuhan, Hubei Province, professor, doctoral supervisor, specializing in mineral processing. Tel: 027-62574946, E-mail: gongwenqi@yahoo.com.cn.
Recumbentite is a regular interlayer clay mineral composed of dioctahedral mica and dioctahedral montmorillonite at 1:1, which has a unique structure, strong adsorption and cation exchange [1, 2]. Scholars at home and abroad have studied the treatment of wastewater with regolith and its modified products [3-5], and promising progress has been made. However, researchers have found that these powdery adsorbent materials for wastewater treatment of the main problems are: adsorbent material particle size is fine, easily dispersed in contact with water pulverization, resulting in the subsequent solid-liquid separation is very difficult, easy to form a new industrial sludge, this industrial sludge due to the enrichment of adsorbent substances on the environment of the secondary pollution of the hazardous; adsorbent materials can not be reused, adsorbent materials can not be recycled, the cost of treatment has increased greatly ［Er.6]. 6]. In order to solve these problems, this paper discusses the process conditions, regeneration method and its application in the treatment of copper smelting industrial wastewater for the removal of heavy metal ions such as Cu2 +, Pb2 +, Zn2 +, Cd2 +, Ni2 + and other heavy metal ions in the copper smelting industrial wastewater, to provide an inexpensive adsorbent material with a good removal effect.
I. Test Part
(I) Test Material
The test recumbent stone was produced in Zhongxiang, Hubei Province, and provided by Hubei Mingliu Recumbent Stone Science and Technology Company. Its chemical composition is: SiO243.82%, Al2O334.25%, Fe2O31.59%, CaO 3.76%, K2O 0.93%, Na2O 1.54%, MgO 0.36%, TiO22.97%; and its mineral composition is: 85% of recumbent stone; 10% of illite; and 5% of kaolinite.
The blast furnace water quenching slag used in the test was taken from Wuhan Iron and Steel Group Corporation ironmaking plant. Its chemical composition is as follows: SiO232.98%, Al2O316.67%, Fe2O30.70%, CaO 35.99%, K2O 0.44%, MgO 8.52%, TiO21.43%. X-ray diffraction phase analysis shows that it is amorphous.
The fly ash used in the test is the dry-discharge fly ash of Hubei Huadian Group Huangshi Power Generation Joint Stock Company. Its chemical composition is: SiO254.72%, Al2O328.65%, Fe2O34.14%, CaO 3.39%, K2O 1.68%, MgO 0.78%, TiO21.22%. Its mineral composition is 15% quartz, 15% mullite and 70% amorphous phase.
The copper smelting industrial wastewater used in the test was taken from the actual wastewater of the copper smelting plant of Daye Nonferrous Metals Company in Huangshi City, Hubei Province, and the results of the water quality analysis were as follows: Cu2＋2.62 mg/dm3, Pb2＋0.63 mg/dm3, Zn2＋3.92 mg/dm3, Cd2＋0.58 mg/dm3, Ni2＋1.48 mg/dm3, pH 6.5.
(II) Test Instruments
D/MAX-RB X-ray diffractometer, ST-2000 Specific Surface Area and Pore Size Detector, XTLZ Multi-Vacuum Filter, F97-Series Closed Assay Sample Crusher, XSB-70 B-type ф200 standard sieve vibration sifter, 20-400 mesh standard test sieve, PHS-3C Acidimeter, SKFO-01 electric drying oven, SX2-4-13 muffle furnace, THZ-82 constant temperature water bath oscillator, AB204-N electronic balance, JY38plus plasma single-channel scanning direct reading spectrometer (ICP-AES).
(III) Test methods
1. Sample preparation
The recombinantite samples were purified by repeated dispersion-sedimentation method, while the water quenching slag and fly ash samples were used directly. The samples were dried and pulverized, and then sieved to less than 240 mesh.
2. Preparation of adsorbent materials of recumbent stone-water quenching slag and recumbent stone-fly ash particles
The prepared water quenching slag or fly ash and recumbent stone were mixed with additives (industrial starch, referred to as IS) and water according to a certain ratio, aged for 24 h, and made into granules with a particle size of 1-3 mm, which were sent to a muffle furnace to bake for 2 h, and then naturally cooled down to room temperature, which is the desired granule adsorbent material. Adsorption material.
3. Treatment of copper smelting industrial wastewater
In a 250 mL conical flask, add 100 mL of copper smelting industrial wastewater, add a certain amount of particles of adsorbent material, put into a constant temperature bath oscillator (oscillation frequency of 110 r/min) reaction for a certain period of time, centrifugal separation, take out the supernatant, determination of the concentration of heavy metal ions and the calculation of its adsorption and removal rate η (%) : η = (Co-Ce)/Co×100%, where Co and Ce are the concentrations of heavy metal ions in the solution before and after adsorption, respectively (mg/dm3).
4. Determination of dissipation rate of granular adsorbent material
Accurately weigh a certain amount of granular adsorbent (G1), put it in a 250 mL conical flask with stopper, add 100 mL of deionized water, and then oscillate it for a certain period of time under certain temperature in a constant temperature water-bath oscillator at a frequency of 110 r/min, and then wash out the powder generated by the crushing of granular adsorbent material with deionized water. Then the wet granular adsorbent material was baked in an oven at 103～105℃ until constant weight, and then weighed after cooling to room temperature (recorded as G2), the formula for calculating the dissipation rate P (%) is [7]:
P=(G1-G2)/G1×100%
Trial results and discussion
In order to simplify the treatment process and reduce the cost of treatment, this test was carried out in the copper smelting plant, which is the most important part of the copper smelting process. In order to simplify the treatment process and reduce the treatment cost, this test was carried out under the natural pH (i.e., without adjusting the pH) of copper smelting industrial wastewater, and the effects of the process conditions of particle adsorbent material preparation, wastewater treatment process conditions, and regeneration and utilization methods of particle adsorbent material on the removal rate of heavy metal elements in wastewater were examined.
(I) The effect of process conditions for the preparation of particle adsorbent materials
1. The effect of roasting temperature
After the comprehensive consideration of the removal rate of Cu and the dissipation rate of particle adsorbent materials from the experimental results, it was determined that the roasting temperatures of recumbent stone-water quenched slag and recumbent stone-fly ash particulate adsorbent materials were 400℃ and 500℃, respectively, in which the removal rate of Cu was higher and the dissipation rate of particulate adsorbent materials was lower than that of the water quenching residue. Cu removal rate is higher and the dissipation rate of the particulate adsorbent material is lower.
2. The effect of the mixing ratio of recombinantite and water-quenched slag or fly ash
The effect of the mixing ratio of recombinantite and water-quenched slag or fly ash on the removal rate of Cu in wastewater can be seen in the experimental results, when the content of recombinantite was increased from 10% to 20%, the removal rate of Cu increased, and then with the increase in the content of recombinantite, the removal rate of Cu showed a decreasing trend, and the rate of scattering was always decreasing with the increase of the content of recombinantite, while the rate of Cu was always decreasing with the increase of the content of recombinantite. The scattering rate has been in a decreasing trend with the increase of the recombinant content. When the content of cumene is more than 50%, the dissipation rate is close to 0. From the point of view of effective utilization of water quenching slag and fly ash, it is determined that the content of cumene is 50%, i.e., the ratio of water quenching slag or fly ash to cumene is 1:1, and the removal rate of Cu is higher and the dissipation rate is very low.
3. The effect of additive ratio
The effect of additive ratio on the removal of Cu from wastewater by the adsorbent material of recondite-water quenching slag or recondite-fly ash particles can be seen from the results of the test: the content of additives in the two kinds of particles of adsorbent material is 10% and 15%, respectively, the removal of Cu is very high, and the rate of dispersion is very low, and the effect of the removal from the point of view of the removal and the cost of the considerations. The contents of additives in these two granular adsorbent materials were determined to be 10% and 15%, respectively.
(II) particle adsorbent material to remove heavy metal elements in copper smelting industrial wastewater
According to the above test to determine the preparation conditions: the ratio of recumbent stone and water quenching slag 1:1, add 10% of the additives and 50% of water, the roasting temperature of 400 ° C.; the ratio of recumbent stone and fly ash 1:1, add another 15% of the additives and 50% of water, the roasting temperature of 500 ° C. Temperature of 500 ℃; were made into particles adsorbent material, used to remove heavy metal elements in copper smelting industrial wastewater conditions test.
1. The effect of reaction time
The effect of reaction time on the removal of heavy metal elements in copper smelting industrial wastewater at room temperature (25℃) and the dosage of granular adsorbent material was 0.03g/cm3. The test results showed that with the prolongation of the reaction time, the removal rate of heavy metal elements had a tendency to increase gradually, and the use of the recumbent quartzite-quenched slag granular adsorbent material 40min later, or the use of recumbent quenched slag granular adsorbent material 40min later. After 40 min of using the regolith-water quenching slag particle adsorbent, or after 60 min of using the regolith-fly ash particle adsorbent, the removal rate tends to equilibrate. Therefore, it was determined that the reaction time of using these two particle adsorbent materials was 40 min and 60 min, respectively.
2. Effect of adsorption temperature
Under the conditions of particle adsorbent dosage of 0.03 g/cm3, reaction time of recumbent stone-water quenched slag particle adsorbent material of 40 min, and recumbent stone-fly ash particle adsorbent material of 60 min, the effect of adsorption temperature on the removal of copper smelting was carried out. The effect of adsorption temperature on the removal of heavy metal elements from copper smelting industrial wastewater was tested. The results showed that the removal of heavy metal elements by both particulate adsorbents was highest at 25℃. Therefore, the adsorption temperature was determined to be 25℃.
3. Effect of the dosage of particulate adsorbent material
The effect of the dosage of these two particulate adsorbents on the removal of heavy metal elements in copper smelting industrial wastewater was tested under the conditions of room temperature (25℃), reaction time of recondite-water quenching slag and recondite-fly ash particulate adsorbent material of 40 and 60 min, respectively, and the results showed that with the increase of the dosage of adsorbent, the removal rate of heavy metal elements gradually increased, and the removal rate of heavy metal elements gradually increased. The results showed that with the increase of adsorbent dosage, the removal rate of heavy metal elements gradually increased. When the dosage of adsorbent of retentate-water quenching slag particles was more than 0.03g/cm3, and the dosage of adsorbent of retentate-fly ash particles was more than 0.05g/cm3, the removal rate of heavy metal elements increased slowly. Therefore, from the cost point of view, it was determined that the dosage of these two kinds of particle adsorbents were 0.03g/cm3 and 0.05g/cm3, respectively.
(III) Orthogonal test results
The above explored the effect of each single-factor (time, temperature, and dosage) conditions on the heavy metal element removal from the industrial wastewater of copper smelting by the cumarind-water quenching slag or cumarind-fly ash particles adsorbent materials. Removal effect. In order to explore the optimal removal effect of particle adsorbent materials on heavy metal elements in this wastewater under the interaction of each single factor, a three-factor two-level orthogonal test was conducted, and the results are shown in Tables 1 and 2.
Table 1 Orthogonal test results of cumene-water quenching slag treatment of copper smelting plant wastewater
Table 2 Orthogonal test results of cumene-fly ash treatment of copper smelting plant wastewater
Analysis of the orthogonal test results can be drawn the following conclusions:
1) The treatment of copper smelting wastewater using cumene-water quenching slag particulate adsorbent material can be carried out under the conditions of natural pH. Reaction temperature is 25℃ (i.e. room temperature), reaction time is 40 min, the dosage of particle adsorbent material is 0.05g/cm3, the removal rate of Cu2＋, Pb2＋, Zn2＋, Cd2＋, Ni2＋ in wastewater is 98.2%, 96.3%, 78.6%, 86.2%, 64.2% respectively, and the Cu2＋, Pb2＋, Zn2＋, Cd2＋, Ni2＋, Ni2＋, Cd2＋, Ni2＋, Ni2＋, Ni2＋ and Ni2＋ are removed respectively in wastewater. Cu2＋, Pb2＋, Zn2＋, Cd2＋, Ni2＋ residual concentrations in the treated wastewater are lower than the national comprehensive sewage discharge standards (GB8978-1996) of the first level.
2) The treatment of copper smelting wastewater using regolith-fly ash particle adsorbent material can be carried out under natural pH conditions, the reaction temperature is 25 ℃ (i.e., room temperature), the reaction time is 60 min, and the dosage of the particle adsorbent material is 0.07 g/cm3, the removal rate of Cu2 +, Pb2 +, Zn2 +, Cd2 +, Ni2 + in the wastewater is 98.9%, respectively, 97.5%, 96.7%, 90.2%, 79.1%, and the residual concentrations of Cu2+, Pb2+, Zn2+, Cd2+, Ni2+ in the treated wastewater were all lower than the national comprehensive sewage discharge standard (GB8978-1996) of the first level.
3) The adsorbent materials of recumbent stone-water quenching slag and recumbent stone-fly ash particles have strong adsorption activity for heavy metal elements in copper smelting industrial wastewater, which is mainly due to the fact that the water quenching slag and the fly ash are porous materials with high activity［8～12］, and the recumbent stone is the regular interlayer clay mineral composed of dioctahedral mica and dioctahedral montmorillonite according to 1∶1 with a larger ratio of surface area and strong adsorption activity. surface area and strong adsorption properties. After mixing them in a certain proportion and adding appropriate amount of industrial starch, after roasting, the regolith loses interlayer water, and the industrial starch is burned through, which increases the specific surface area of the particulate adsorbent material, and also strengthens the adsorption performance of heavy metal ions.
(IV) Results of regeneration test of particle adsorbents
Table 3 Results of regeneration test of particulate adsorbent materials of cumulite-water quenched slag
Table 4 Results of regeneration test of particulate adsorbent materials of cumulite-fly ash
The particulate adsorbent materials adsorbed saturated under the optimal adsorption conditions of orthogonal tests were washed with deionized water for 3 times, dried and then treated with different desorbent agents ( HNO3, HCl, NaCl) for desorption and regeneration test, every 2 h stirring 2 min, desorption 12 h, and then repeated cleaning with deionized water, until no Cl- in the cleaning solution or , drying, and then copper smelting industrial wastewater adsorption treatment, the results of the test are shown in Tables 3 and 4. from the table can be seen, 1 mol / L NaCl desorption and regeneration is the best effect, the treatment of wastewater in Cu2 ＋, Pb2 ＋, Zn2 ＋, Cd2 ＋, Ni2 ＋ residual concentration is still lower than the national comprehensive sewage discharge standards (GB8978-1996) of the first level of standards, the removal rate with the removal rate of the newly prepared particles of adsorbent material is very close to the removal rate, in the desorption of regeneration 6 times, the removal rate of the removal rate of the new material is 80%, indicating that the prepared particles of adsorbent material reuse effect is better. This shows that the effect of the prepared particle adsorbent material is good for reuse.
III. Conclusion
1) The process conditions for the preparation of cumene-water quenching slag and cumene-fly ash particle adsorbent materials are as follows: the ratio of cumene to water quenching slag is 1:1, with 10% additives (IS) and 50% water, and the roasting temperature is 400℃; the ratio of cumene to fly ash is 1:1, with 15% additives (IS) and 50% water, and the roasting temperature is 500℃; the ratio of cumene to fly ash is 1:1, with 15% additives (IS) and 50% water, and the roasting temperature is 400℃; and the ratio of cumene to fly ash is 1:1, with 15% additives (IS) and 50% water, and the roasting temperature is 500℃. water, and the roasting temperature was 500 °C. The made granular adsorbent material not only has good adsorption effect, but also has low dissipation rate.
2) The suitable conditions for the removal of heavy metal elements from copper smelting industrial wastewater by regolith-water quenching slag granular adsorbent material are: under the condition of natural pH, the dosage of granular adsorbent is 0.05g/cm3, the reaction time is 40 min, and the temperature is 25℃ (room temperature). The removal rates of Cu2+, Pb2+, Zn2+, Cd2+, and Ni2+ under this condition were 98.2%, 96.3%, 78.6%, 86.2%, and 64.2%, respectively. The suitable conditions for the removal of heavy metal elements from copper smelting industrial wastewater by regolith-fly ash granular adsorbent materials were as follows: the dosage of granular adsorbent was 0.07 g/cm3 under the condition of natural pH, the reaction time was 60 min, and the temperature was 25°C (room temperature). The removal rates of Cu2+, Pb2+, Zn2+, Cd2+ and Ni2+ under these conditions were 98.9%, 97.5%, 96.7%, 90.2% and 79.1%, respectively. The residual concentrations of these heavy metal elements in the treated wastewater were lower than the primary standard of the National Comprehensive Sewage Discharge Standard (GB8978-1996).
3) The particulate adsorbent material saturated with 1 mol/L NaCl under the best adsorption conditions was desorbed and regenerated, and then used to treat the industrial wastewater of copper smelting, and the residual concentrations of Cu2+, Pb2+, Zn2+, Cd2+, Ni2+ in the treated wastewater were still lower than the first-grade standard of the national comprehensive wastewater discharge standard (GB8978-1996), and the removal rate was lower than the first-grade standard of the national comprehensive wastewater discharge standard (GB8978-1996). 1996), and the removal rate is very close to that of the newly prepared granular adsorbent material. Compared with other adsorbent materials, the particle adsorbent material has the advantages of easy separation, reusable, low cost and good treatment effect, and thus has a good application prospect.
References
[1] Jiang T, Liu Yuanjun. Reciprocal stone. Wuhan: Hubei Science and Technology Press, 1989: 1-48
[2] Zhang Xiaoqing. Modification of regolith and its application in wastewater treatment. Journal of Northwestern Polytechnical University, 2003
[3] Sun Jashou, Zhang Zeqiang, Liu Yu. Study on the treatment of chromium-containing wastewater by regolith layered porous materials. Journal of Rock Mineralogy, 2001, 20(4):555-558
[4] J.S. Sun, S.C. Bao, Ch.L. Li, et al. Study on the treatment of cyanide-containing electroplating wastewater by modified regolith. Nonmetallic Mining, 2001, (1)
[5] Wang Hukun, Gong Wenqi. Application of clay mineral materials in heavy metal wastewater treatment. Industrial Water Treatment, 2006, 26(4):4-7
[6] Sun Xiuyun, Wang Lianjun, Zhou Xuetie. Preparation and modification of adsorbent of bumpy clay-fly ash particles. Jiangsu Environmental Science and Technology, 2003, 16(2):1-3
[7] D.H. Wu, Y.G. Wu, R.R. Lin. Structural properties and hydration mechanism of blast furnace water quenching slag. Oil Drilling Technology, 1997, (1)
[8] Pengju Xu, Qinyan Yue, Yanna Zhang, et al. PDMDAAC modified blast furnace slag treatment of printing and dyeing wastewater. Industrial Water Treatment, 2006, (5), 62-64
[9] Li Yafeng, Sun Fenghai, Niu Evening Yang et al. Mechanism and application of fly ash treatment of wastewater. Mining Safety and Environmental Protection, 2001, (02)
[10] Li Chunqing, Pu Hongping. Modification of fly ash and its application in wastewater treatment. China Comprehensive Utilization of Resources, 2006, (11)
[11] CHENG Aihua, WANG Jiandong, YAO Changhuan. Application of fly ash in water treatment. Energy and Environment, 2006, (01)
Preparation of clay functional materials and their application in treatment of heavy metal-containing wastewater
Gong Wenqi, Han Pei, Wang Hukun, Liu Yanju, Rao Boqiong
(School of Resources and Environmental Engineering, Wuhan University of Technology. Wuhan 430070, Hubei, China)
Abstract: The preparation technological conditions and regeneration method of two novel granulated adsorbing materials of rectorite/fly ash were investigated. The preparation technological conditions and regeneration method of two novel granulated adsorbing materials of rectorite/fly ash composite (Material 1) and rectorite/water quenched-slag composite (Material 2) and the use of them to remove heavy metals from copper smelting plant wastewater have been studied.The experimental results showed that under the preparation conditions with the ratio of The experimental results showed that under the preparation conditions with the ratio of rectorite to fly ash or water quenched slag of 1:1, the amount of the additive (Industrial Starch, IS) of 15% (Material 1) or 10% (Material 2), the addition of 50% water, and the use of them to remove heavy metals from copper smelting plant wastewater have been studied. of 50% water, and the calcination temperature of 500°C (Material 1) or 400°C (Material 2), the efficiency of heavy metal removal with the granulated materials was the best, whereas the ra tio of disintegration loss was low.Under the treatment conditions of natural pH, and with the addition of the Under the treatment conditions of natural pH, and with the addition of the granulated materials of 0.07g/cm3 (Material 1) or 0.05g/cm3 (Material 2), a reaction time of 60 minutes (Material 1) or 40 minutes (Material 2), and the adsorption temperature of 25℃, the efficiency for the granulated materials to remove Cu2+, Pb2+, Zn2+, Cd2+and Ni2+from copper smelting plant wastewater was 98 9%. wastewater was 98.9%, 97.5%, 96.7%, 90.2% and 79.1% (Material 1) or 98.2%, 96.3%, 78.6%, 86.2% and 64.2% (Material 2), respectively, and the quality indexes of the wastewater after the treatment of copper smelting plant. indexes of the wastewater after treatment conformed with the first level of integrated wastewater discharge standard (GB8978-1996) . The granulated materials saturat ed with heavy metal ions on the surface could be regenerated with quite good efficiency by washing with 1 mol/L sodium The granulated adsorbing materials had the advantages of high efficiency in wastewater treatment, easy method of solid-liquid separation and regeneration, and the ability of the granulated adsorbing materials to be used in the treatment of wastewater. The granulated adsorbing material had the advantages of high efficiency in wastewater treatment, easy method of solid-liquid separation and regeneration, and have a broad prospect of applications.
Key words: Rectorite, water quenched-slag, fly ash; granulated adsorbing material, regeneration, copper smelting plant wastewater.