Journal of Guangxi Normal University(Natural Science Edition) ›› 2026, Vol. 44 ›› Issue (3): 214-224.doi: 10.16088/j.issn.1001-6600.2025051901

• Ecology and Environmental Science Research • Previous Articles     Next Articles

Performance and Mechanism of Zinc-Manganese-Iron Modified Biochar in Removing Cadmium from Wastewater

DUAN Ziyan1,2, YE Shunyun1,2, ZHANG Junyu1,2, LI Anyu1,2*, SU Ming1,2, JIANG Feng1,2, DENG Hua1,2*   

  1. 1. Guangxi Key Laboratory of Environmental Processes and Remediation in Ecologically Fragile Regions (Guangxi Normal University), Guilin Guangxi 541006, China;
    2. University Engineering Research Center of Green Remediation and Low Carbon Development for Lijiang River Basin (Guangxi Normal University), Guilin Guangxi 541006, China
  • Received:2025-05-19 Revised:2025-09-09 Online:2026-05-05 Published:2026-05-13

PDF (PC)

1

Abstract: Heavy metal pollution is widespread and increasingly severe, cadmium (Cd) in water is potentially toxic, and can be transferred and enriched into the human body through the food chain and other ways, endangering human health. Adsorption method has garnered significant attention in the treatment of heavy metal pollution, and different biomass materials can affect the adsorption effect of biochar on heavy metals in water to a certain extent. In this study, magnetic pomelo peel biochar (ZMF@BC) was prepared from agricultural waste pomelo peel as raw material via zinc-manganese-iron impregnation modification to investigate the removal effect and mechanism of biochar on Cd(Ⅱ) in water under different conditions. The adsorption performance of ZMF@BC on Cd(Ⅱ) was analyzed by coexisting ion competition adsorption, adsorption-desorption, etc. The adsorption mechanism was also explored using batch adsorption experiments, Fourier Transform Infrared Spectroscopy (FT-IR), and X-ray Diffraction Analysis (XRD). The results showed that at pH 6.0, the biochar adsorbed Cd(Ⅱ) with a maximum adsorption capacity of 26.3 mg/g due to the reduced ionic competitiveness, and the competitive adsorption of Cd(Ⅱ) by common cations coexisting in the water was in the following order: Na+> Mg2+> Ca2+> K+. The adsorption of Cd(Ⅱ) by ZMF@BC was in accordance with Langmuir and quasi-secondary kinetic models, suggesting monolayer chemical adsorption. The thermodynamic results showed that the adsorption process was spontaneous, and the adsorption-desorption could maintain 85.1% of the initial adsorption amount after five adsorption-desorption cycles. ZMF@BC can absorb Cd(Ⅱ) through ion exchange by using the Zn, Fe, and Mn in the metal oxides on its surface, and also be immobilized through the complexation mechanism specific to the iron oxides.

Key words: cadmium, biochar, modified, adsorption, mechanism, wastewater

CLC Number:  X703
[1] DIAO Z H, QIAN W, ZHANG Z W, et al. Removals of Cr(Ⅵ) and Cd(Ⅱ) by a novel nanoscale zero valent iron/peroxydisulfate process and its Fenton-like oxidation of pesticide atrazine: coexisting effect, products and mechanism[J]. Chemical Engineering Journal, 2020, 397: 125382. DOI: 10.1016/j.cej.2020.125382.
[2] GAO S K, ZHANG R, ZHANG H, et al. The seasonal variation in heavy metal accumulation in the food web in the coastal waters of Jiangsu based on carbon and nitrogen isotope technology[J]. Environmental Pollution, 2022, 297: 118649. DOI: 10.1016/j.envpol.2021.118649.
[3] ZHANG Y T, LI A Y, LIU L H, et al. Enhanced remediation of cadmium-polluted soil and water using facilely prepared MnO2-coated rice husk biomass[J]. Chemical Engineering Journal, 2023, 457: 141311. DOI: 10.1016/j.cej.2023.141311.
[4] DENG F X, OLVERA-VARGAS H, GARCIA-RODRIGUEZ O, et al. Waste-wood-derived biochar cathode and its application in electro-Fenton for sulfathiazole treatment at alkaline pH with pyrophosphate electrolyte[J]. Journal of Hazardous Materials, 2019, 377: 249-258. DOI: 10.1016/j.jhazmat.2019.05.077.
[5] 李晓佳, 王然登, 荣宏伟, 等. 生物除磷颗粒污泥去除Pb2+的效能机制[J]. 化工学报, 2018, 69(4): 1663-1669.
[6] HU B W, AI Y J, JIN J, et al. Efficient elimination of organic and inorganic pollutants by biochar and biochar-based materials[J]. Biochar, 2020, 2(1): 47-64. DOI: 10.1007/s42773-020-00044-4.
[7] QU J H, LIU Y, CHENG L, et al. Green synthesis of hydrophilic activated carbon supported sulfide nZVI for enhanced Pb(II) scavenging from water: characterization, kinetics, isotherms and mechanisms[J]. Journal of Hazardous Materials, 2021, 403: 123607. DOI: 10.1016/j.jhazmat.2020.123607.
[8] AN Q, JIANG Y Q, NAN H Y, et al. Unraveling sorption of nickel from aqueous solution by KMnO4 and KOH-modified peanut shell biochar: implicit mechanism[J]. Chemosphere, 2019, 214: 846-854. DOI: 10.1016/j.chemosphere.2018.10.007.
[9] 丁苏雅, 马姜明, 覃云斌, 等. 生物炭对毛竹林土壤有机碳组分及碳库管理指数的影响[J]. 广西师范大学学报(自然科学版), 2024, 42(1): 180-190. DOI: 10.16088/j.issn.1001-6600.2023020701.
[10] SIZMUR T, FRESNO T,AKGÜL G, et al. Biochar modification to enhance sorption of inorganics from water[J]. Bioresource Technology, 2017, 246: 34-47. DOI: 10.1016/j.biortech.2017.07.082.
[11] YAN L L, LIU Y, ZHANG Y D, et al. ZnCl2 modified biochar derived from aerobic granular sludge for developed microporosity and enhanced adsorption to tetracycline[J]. Bioresource Technology, 2020, 297: 122381. DOI: 10.1016/j.biortech.2019.122381.
[12] LI H, ALI MAHYOUB S A, LIAO W J, et al. Effect of pyrolysis temperature on characteristics and aromatic contaminants adsorption behavior of magnetic biochar derived from pyrolysis oil distillation residue[J]. Bioresource Technology, 2017, 223: 20-26. DOI: 10.1016/j.biortech.2016.10.033.
[13] SUN Y Q, YU I K M, TSANG D C W, et al. Multifunctional iron-biochar composites for the removal of potentially toxic elements, inherent cations, and hetero-chloride from hydraulic fracturing wastewater[J]. Environment International, 2019, 124: 521-532. DOI: 10.1016/j.envint.2019.01.047.
[14] YANG T T, XU Y M, HUANG Q Q, et al. Removal mechanisms of Cd from water and soil using Fe-Mn oxides modified biochar[J]. Environmental Research, 2022, 212: 113406. DOI: 10.1016/j.envres.2022.113406.
[15] TENG D Y, ZHANG B B, XU G M, et al. Efficient removal of Cd(II) from aqueous solution by pinecone biochar: sorption performance and governing mechanisms[J]. Environmental Pollution, 2020, 265: 115001. DOI: 10.1016/j.envpol.2020.115001.
[16] TAN W T, ZHOU H, TANG S F, et al. Enhancing Cd(II) adsorption on rice straw biochar by modification of iron and manganese oxides[J]. Environmental Pollution, 2022, 300: 118899. DOI: 10.1016/j.envpol.2022.118899.
[17] LIANG J, XU X Y, QAMAR ZAMAN W, et al. Different mechanisms between biochar and activated carbon for the persulfate catalytic degradation of sulfamethoxazole: roles of radicals in solution or solid phase[J]. Chemical Engineering Journal, 2019, 375: 121908. DOI: 10.1016/j.cej.2019.121908.
[18] KONG X D, GAO H P, SONG X L, et al. Adsorption of phenol on porous carbon from Toona sinensis leaves and its mechanism[J]. Chemical Physics Letters, 2020, 739: 137046. DOI: 10.1016/j.cplett.2019.137046.
[19] YU S J, WANG J, SONG S, et al. One-pot synthesis of graphene oxide and Ni-Al layered double hydroxides nanocomposites for the efficient removal of U(VI) from wastewater[J]. Science China Chemistry, 2017, 60(3): 415-422. DOI: 10.1007/s11426-016-0420-8.
[20] NZEDIEGWU C, NAETH M A, CHANG S X. Lead(II) adsorption on microwave-pyrolyzed biochars and hydrochars depends on feedstock type and production temperature[J]. Journal of Hazardous Materials, 2021, 412: 125255. DOI: 10.1016/j.jhazmat.2021.125255.
[21] JUNG K W, CHOI B H, JEONG T U, et al. Facile synthesis of magnetic biochar/Fe3O4 nanocomposites using electro-magnetization technique and its application on the removal of Acid Orange 7 from aqueous media[J]. Bioresource Technology, 2016, 220: 672-676. DOI: 10.1016/j.biortech.2016.09.035.
[22] YANG T T, XU Y M, HUANG Q Q, et al. Adsorption characteristics and the removal mechanism of two novel Fe-Zn composite modified biochar for Cd(II) in water[J]. Bioresource Technology, 2021, 333: 125078. DOI: 10.1016/j.biortech.2021.125078.
[23] 邹成龙, 吴群, 聂发辉, 等. MgFe-LDH@柚子皮生物炭复合材料吸附Gd(Ⅲ)的性能研究[J]. 环境科学与技术, 2024, 47(10): 58-68. DOI: 10.19672/j.cnki.1003-6504.1084.24.338.
[24] 邓华, 张俊渝, 黄瑞, 等. 竹炭负载氧化锌对Cr(Ⅵ)的吸附性能和机理[J]. 广西师范大学学报(自然科学版), 2023, 41(1): 131-142. DOI: 10.16088/j.issn.1001-6600.2022010501.
[25] 唐思琦, 郑子龙, 谭玲, 等. 镁铁双金属氧化物改性骨源生物炭对Pb2+吸附特性研究[J]. 现代化工, 2025, 45(8): 117-123, 129. DOI: 10.16606/j.cnki.issn0253-4320.2025.08.022.
[26] 陈壮, 梁媛, 赵奔, 等. 改性生物炭对Cr(Ⅵ)的吸附特性研究[J]. 复旦学报(自然科学版), 2021, 60(6): 779-788. DOI: 10.15943/j.cnki.fdxb-jns.2021.06.007.
[27] LI A Y, GE W Z, LIU L H, et al. Synthesis and application of amine-functionalized MgFe2O4-biochar for the adsorption and immobilization of Cd(Ⅱ) and Pb(Ⅱ)[J]. Chemical Engineering Journal, 2022, 439: 135785. DOI: 10.1016/j.cej.2022.135785.
[28] ZHU S H, ZHAO J J, ZHAO N, et al. Goethite modified biochar as a multifunctional amendment for cationic Cd(Ⅱ), anionic As(Ⅲ), roxarsone, and phosphorus in soil and water[J]. Journal of Cleaner Production, 2020, 247: 119579. DOI: 10.1016/j.jclepro.2019.119579.
[29] GAO J, ZHAO T K, TSANG D C W, et al. Effects of Zn in sludge-derived biochar on Cd immobilization and biological uptake by lettuce[J]. Science of the Total Environment, 2020, 714: 136721. DOI: 10.1016/j.scitotenv.2020.136721.
[30] RAJAPAKSHA A U, CHEN S S, TSANG D C W, et al. Engineered/designer biochar for contaminant removal/immobilization from soil and water: potential and implication of biochar modification[J]. Chemosphere, 2016, 148: 276-291. DOI: 10.1016/j.chemosphere.2016.01.043.
[31] CHEN X J, LIN Q M, XIAO H Y, et al. Manganese-modified biochar promotes Cd accumulation in Sedum alfredii in an intercropping system[J]. Environmental Pollution, 2023, 317: 120525. DOI: 10.1016/j.envpol.2022.120525.
[32] WANG C B, LI X P, WU W Z, et al. Removal of cadmium in water by potassium hydroxide activated biochar produced from Enteromorpha prolifera[J]. Journal of Water Process Engineering, 2021, 42: 102201. DOI: 10.1016/j.jwpe.2021.102201.
[33] MOHAN D, SINGH P, SARSWAT A, et al. Lead sorptive removal using magnetic and nonmagnetic fast pyrolysis energy cane biochars[J]. Journal of Colloid and Interface Science, 2015, 448: 238-250. DOI: 10.1016/j.jcis.2014.12.030.
[34] 李安玉, 李双莉, 余碧戈, 等. 镁浸渍生物炭吸附氨氮和磷: 制备优化和吸附机理[J]. 化工学报, 2020, 71(4): 1683-1695.
[35] LI J, LI B, HUANG H M, et al. Removal of phosphate from aqueous solution by dolomite-modified biochar derived from urban dewatered sewage sludge[J]. Science ofthe Total Environment, 2019, 687: 460-469. DOI: 10.1016/j.scitotenv.2019.05.400.
[36] NIU C W, ZHANG N, HU C C, et al. Preparation of a novel citric acid-crosslinked Zn-MOF/chitosan composite and application in adsorption of chromium(Ⅵ) and methyl orange from aqueous solution[J]. Carbohydrate Polymers, 2021, 258: 117644. DOI: 10.1016/j.carbpol.2021.117644.
[37] 梁恒尧, 郭楚玲, 李晓飞, 等. 磷酸盐对镉在纤铁矿上吸附行为的影响机制研究[J]. 环境科学学报, 2025, 45(1): 166-176. DOI: 10.13671/j.hjkxxb.2024.0319.
[38] GU Y, XIE D H, WANG Y C, et al. Facile fabrication of composition-tunable Fe/Mg bimetal-organic frameworks for exceptional arsenate removal[J]. Chemical Engineering Journal, 2019, 357: 579-588. DOI: 10.1016/j.cej.2018.09.174.
[39] 王江南, 孙晓雪, 杨玲辉, 等. 壳聚糖、铁锰改性稻壳生物炭的表征及其Cd2+吸附性能研究[J]. 农业环境科学学报, 2023, 42(9): 1964-1973.
[40] HUANG Y J, KONG Q D, ZHANG X J, et al. DMSA-incorporated silsesquioxane-based hybrid polymer for selective adsorption of Pb(Ⅱ) from wastewater[J]. Journal of Molecular Liquids, 2022, 368: 120723. DOI: 10.1016/j.molliq.2022.120723.
[41] ZHOU Y Z, LI Y, LIU D X, et al. Adsorption optimization of uranium(Ⅵ) onto polydopamine and sodium titanate co-functionalized MWCNTs using response surface methodology and a modeling approach[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021, 627: 127145. DOI: 10.1016/j.colsurfa.2021.127145.
[42] 周育智, 龙林丽, 胡翩, 等. 聚多巴胺修饰矸石基沸石净化含镉污水性能与机制[J]. 中国环境科学, 2025, 45(7): 3762-3770. DOI: 10.19674/j.cnki.issn1000-6923.20250114.001.
[43] JIA X X, WANG H S, LI Y T, et al. Separable lanthanum-based porous PAN nanofiber membrane for effective aqueous phosphate removal[J]. Chemical Engineering Journal, 2022, 433: 133538. DOI: 10.1016/j.cej.2021.133538.
[44] ARAMI M, LIMAEE N Y, MAHMOODI N M. Evaluation of the adsorption kinetics and equilibrium for the potential removal of acid dyes using a biosorbent[J]. Chemical Engineering Journal, 2008, 139(1): 2-10. DOI: 10.1016/j.cej.2007.07.060.
[45] 马锋锋, 郑旭东, 赵浩, 等. 改性生物炭吸附焦化废水中苯酚和氨氮的特性及机制[J]. 环境科学, 2025, 46(7): 4349-4359. DOI: 10.13227/j.hjkx.202406156.
[46] MA F F, ZHAO H, ZHENG X D, et al. Enhanced adsorption of cadmium from aqueous solution by amino modification biochar and its adsorption mechanism insight[J]. Journal of Environmental Chemical Engineering, 2023, 11(3): 109747. DOI: 10.1016/j.jece.2023.109747.
[47] DENG J Q, FANG Y, HOU C L, et al. Ultrasonic assisted activation of persulfate for the treatment of spent porous biochar:Degradation of adsorbed PFOA and adsorbent regeneration[J]. Journal of Environmental Chemical Engineering, 2023, 11(6): 111146. DOI: 10.1016/j.jece.2023.111146.
[48] IAMSAARD K, WENG C H, YEN L T, et al. Adsorption of metal on pineapple leaf biochar: key affecting factors, mechanism identification, and regeneration evaluation[J]. Bioresource Technology, 2022, 344(PtA): 126131. DOI: 10.1016/j.biortech.2021.126131.
[49] JIA L, CHENG P, YU Y, et al. Regeneration mechanism of a novel high-performance biochar mercury adsorbent directionally modified by multimetal multilayer loading[J]. Journal of Environmental Management, 2023, 326: 116790. DOI: 10.1016/j.jenvman.2022.116790.
[1] QIAN Junlei, WANG Xizhi, ZENG Kai, DU Xueqiang, LIU He, ZHU Liguang. Steel Surface Defect Detection Algorithm Based on MHTD-YOLO11n [J]. Journal of Guangxi Normal University(Natural Science Edition), 2026, 44(3): 60-74.
[2] WANG Xingyu, ZHENG Haonan, LIU Xiao, CUI Shilong, CAI Jinjun. Research Progress on Preparation of Chitosan-based Adsorbents andTheir Applications Towards Adsorptive Removal of Pollutants From Water [J]. Journal of Guangxi Normal University(Natural Science Edition), 2026, 44(2): 17-30.
[3] SHI Lei, DONG Qiubin, ZENG Minghua. Dynamic Correlation Between [Cu10O(OH)12]6+ and Disordered SiF2-6in Stable Cluster-based MOF and Implications for Selective Adsorption [J]. Journal of Guangxi Normal University(Natural Science Edition), 2026, 44(2): 211-217.
[4] LIU Zhihao, LI Zili, SU Min. YOLOv8-based Helmet Detection Method for Electric Vehicle Riders Combining Intelligent Communication and UAV-Assistance [J]. Journal of Guangxi Normal University(Natural Science Edition), 2026, 44(1): 23-32.
[5] SHI Zihao, MENG Zuqiang, TAN Chaohong. A Detection Model for Multimodal Fake News Based on Attention Mechanism and Multiscale Fusion [J]. Journal of Guangxi Normal University(Natural Science Edition), 2026, 44(1): 68-79.
[6] YAN Qiuxiao, WEI Fuxiao, LIN Shaoxia, JIANG Yangming, DENG Tingfei, WANG Daoping, HUANG Dongfu. Effects of Different Calcium and Cadmium Stoichiometric Relationships on Physiology and Biochemistry in Capsicum annuum L. [J]. Journal of Guangxi Normal University(Natural Science Edition), 2026, 44(1): 143-155.
[7] WANG Xu, CHEN Wei, CAO Liang, XIA Yingjie, ZENG Ming. Removal Mechanism of Cadmium Containing Wastewater by Algae-Bacteria Granular Sludge [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(6): 233-244.
[8] LI Fengwei, TAN Yumei, SONG Shuxiang, XIA Haiying. Occlusion-Aware Facial Expression Recognition Based on Attention Guidance [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(5): 104-113.
[9] TIAN Sheng, XIONG Chenyin, LONG Anyang. Point Cloud Classification Method of Urban Roads Based on Improved PointNet++ [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(4): 1-14.
[10] HAN Shuo, JIANG Linfeng, YANG Jianbin. Attention-based PINNs Method for Solving Saint-Venant Equations [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(4): 58-68.
[11] SHI Tianyi, NAN Xinyuan, GUO Xiangyu, ZHAO Pu, CAI Xin. Improved ConvNeXt-based Algorithm for Apple Leaf Disease Classification [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(4): 83-96.
[12] LI Li, JIANG Miao. Byzantine Fault-Tolerant Consensus Mechanism Based on Raft Improvement [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(4): 108-119.
[13] NIE Qinping, WANG Zirui, HOU Xiaomin, WU Qingfeng. Effect of Montmorillonite-Humic Acid Composite Particles on Photolysis of Tetracycline [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(4): 165-174.
[14] LU Zhanyue, CHEN Yanping, YANG Weizhe, HUANG Ruizhang, QIN Yongbin. Relational Extraction Method Based on Mask Attention and Multi-feature Convolutional Networks [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(3): 12-22.
[15] SUN Jianmei, YANG Yan, SONG Yizhi, SHEN Zhouyang, TANG Zongxiang. Mitigating Effect and Mechanism of p-Coumaric Acid on Gout [J]. Journal of Guangxi Normal University(Natural Science Edition), 2025, 43(3): 183-192.
Viewed
Full text


Abstract

Cited
  Shared   
  Discussed   
[1] MENG Chunmei, LU Shiyin, LIANG Yonghong, MO Xiaomin, LI Weidong, HUANG Yuanjie, CHENG Xiaojing, SU Zhiheng, ZHENG Hua. Electron Microscopy Study on the Apoptosis and Autophagy of the Hepatic Stellate Cells Induced by Total Alkaloids[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 76 -79 .
[2] LI Yuhui, CHEN Zening, HUANG Zhonghao, ZHOU Qihai. Activity Time Budget of Assamese macaque (Macaca assamensis) during Rainy Season in Nonggang Nature Reserve, Guangxi, China[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 80 -86 .
[3] ZHUANG Fenghong, MA Jiangming, ZHANG Yajun, SU Jing, YU Fangming. Eco-Physiological Responses of Leaves of Isoetes sinensis to Light Intensity[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 93 -100 .
[4] WEI Hongjin, ZHOU Xile, JIN Dongmei, YAN Yuehong. Additions to the Pteridophyte Flora of Hunan, China[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 101 -106 .
[5] BAO Jinping, ZHENG Lianbin, YU Keli, SONG Xue, TIAN Jinyuan, DONG Wenjing. Skinfold Thickness Characteristics of Yi Adults in Daliangshan,China[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 107 -112 .
[6] LIN Yongsheng, PEI Jianguo, ZOU Shengzhang, DU Yuchao, LU Li. Red Bed Karst and Its Hydrochemical Characteristics of Groundwater in the Downstream of Qingjiang River, China[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 113 -120 .
[7] ZHANG Ru, ZHANG Bei, REN Hongrui. Spatio-temporal Dynamics Analysis and Its Affecting Factors of Cropland Loss in Xuangang Mining Area, Shanxi, China[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 121 -132 .
[8] LI Xianjiang, SHI Shuqin, CAI Weimin, CAO Yuqing. Simulation of Land Use Change in Tianjin Binhai New Area Based on CA-Markov Model[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 133 -143 .
[9] WANG Mengfei, HUANG Song. Spatial Linkage of Tourism Economy of Cities in West River Economic Belt in Guangxi, China[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 144 -150 .
[10] LIU Guolun, SONG Shuxiang, CEN Mingcan, LI Guiqin, XIE Lina. Design of Bandwidth Tunable Band-Stop Filter[J]. Journal of Guangxi Normal University(Natural Science Edition), 2018, 36(3): 1 -8 .
Copyright © Journal of Guangxi Normal University(Natural Science Edition), All Rights Reserved.
Tel: 0773-5857325　E-mail: gxsdzkb@mailbox.gxnu.edu.cn
Powered by Beijing Magtech Co. Ltd